Pulling the PTU Fuse
#21
08-17-2010, 08:39 AM
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Re: Pulling the PTU Fuse
From '07 FEH/MMH Workshop Manual.
Principles of Operation
The vehicle is equipped with an intelligent 4-wheel drive (4WD) system that is always active and requires no driver input. The system has no mode select switch. The system combines transparent all-surface operation with highly capable 4WD, and is capable of handling all road conditions, including street and highway driving as well as off-road and winter driving.
The 4WD system continuously monitors vehicle conditions and automatically adjusts the torque distribution between the front and rear wheels. During normal operation, most of the torque is sent to the front wheels. If wheel slip*** between the front and rear wheels is detected***, or if the vehicle is under heavy acceleration (high throttle position), the 4WD system increases torque to the rear wheels*** to prevent or control wheel slip.
The 4X4 control module varies the torque sent to the rear wheels by varying a pulse-width modulated current to the clutch in the rear axle. The 4X4 control module also provides the brake system with its current clutch duty cycle and whether or not the brake system may take command of the clutch duty cycle.***
NOTE: The active torque coupling is not repairable. If replacement is required, the active torque coupling and rear axle are replaced as an assembly.
The PTU is a gearbox that attaches to the transaxle.
On automatic transaxle vehicles, the RH halfshaft passes through the transfer case and engages the differential side gear as in normal FWD applications. The transaxle differential drives the PTU.
On manual transmission vehicles, the PTU is directly driven by a gear in the transmission. The halfshaft/intermediate shaft connects directly to the transmission differential by passing through the PTU. The PTU then drives the driveshaft at all times. The driveshaft drives one half of the rear axle clutch pack. The other half of the rear axle clutch pack drives the rear axle ring and pinion.
NOTE: PTU repair is limited to seals, gaskets and output flanges. If any of the geared components, bearings, case cover or internal shafts fail, a new transfer case must be installed.
The PTU is sealed from the transaxle and has its own oil sump. The PTU on an automatic transaxle vehicle uses 355 ml (12 oz) of SAE 75W-140 gear lubricant. The PTU on a manual transaxle vehicle uses 350 ml (12 oz) of SAE 80W-90 gear lubricant.
The active, on-demand 4WD system uses data from other systems as inputs to the 4X4 control module. The 4X4 control module uses the inputs to determine the appropriate amount of current to send to the active torque coupling that delivers the desired torque to the rear wheels. Specific inputs to the 4X4 control module are:
Principles of Operation
The vehicle is equipped with an intelligent 4-wheel drive (4WD) system that is always active and requires no driver input. The system has no mode select switch. The system combines transparent all-surface operation with highly capable 4WD, and is capable of handling all road conditions, including street and highway driving as well as off-road and winter driving.
The 4WD system continuously monitors vehicle conditions and automatically adjusts the torque distribution between the front and rear wheels. During normal operation, most of the torque is sent to the front wheels. If wheel slip*** between the front and rear wheels is detected***, or if the vehicle is under heavy acceleration (high throttle position), the 4WD system increases torque to the rear wheels*** to prevent or control wheel slip.
The 4X4 control module varies the torque sent to the rear wheels by varying a pulse-width modulated current to the clutch in the rear axle. The 4X4 control module also provides the brake system with its current clutch duty cycle and whether or not the brake system may take command of the clutch duty cycle.***
NOTE: The active torque coupling is not repairable. If replacement is required, the active torque coupling and rear axle are replaced as an assembly.
The PTU is a gearbox that attaches to the transaxle.
On automatic transaxle vehicles, the RH halfshaft passes through the transfer case and engages the differential side gear as in normal FWD applications. The transaxle differential drives the PTU.
On manual transmission vehicles, the PTU is directly driven by a gear in the transmission. The halfshaft/intermediate shaft connects directly to the transmission differential by passing through the PTU. The PTU then drives the driveshaft at all times. The driveshaft drives one half of the rear axle clutch pack. The other half of the rear axle clutch pack drives the rear axle ring and pinion.
NOTE: PTU repair is limited to seals, gaskets and output flanges. If any of the geared components, bearings, case cover or internal shafts fail, a new transfer case must be installed.
The PTU is sealed from the transaxle and has its own oil sump. The PTU on an automatic transaxle vehicle uses 355 ml (12 oz) of SAE 75W-140 gear lubricant. The PTU on a manual transaxle vehicle uses 350 ml (12 oz) of SAE 80W-90 gear lubricant.
The active, on-demand 4WD system uses data from other systems as inputs to the 4X4 control module. The 4X4 control module uses the inputs to determine the appropriate amount of current to send to the active torque coupling that delivers the desired torque to the rear wheels. Specific inputs to the 4X4 control module are:
Then there is this statement...
"...whether or not the brake system may take command of the clutch duty cycle..."
The way I read the description of TC, Traction Control, operation the INSTANT front wheelspin/slip is detected the engine will be dethrottled and the front brakes will be activated in order to more quickly alleviate the potential for loss of directional control.
So yes, the Ford 4WD(F/awd) system will just as instantly increase the torque coupling to the rear wheels but the effect, advantage, of this action might/will be completely masked, overshadowed, by TC, TC "braking", immediately taking control of the clutch duty cycle. These types of F/awd systems will almost always disable the F/R torque coupling device/medium if braking is required as it can be somewhat hazardous to have front braking automatically "reflected" on, coupled to, the rear wheels.
Anyone have actual experience with this, is there really an advantage to the Ford 4WD(F/awd) in this type of instance...??
Toyota, in order for this type same type of 4WD (F/awd) system to be advantageous in their vehicles in the above circumstance has been forced into adding a TC disable switch that the driver can use manually.
If the need arises TC can also be disabled by removing the ABS pumpmotor fuse, but that also disables ABS itsself. A better was may be to create/cause a "false" CEL by temporarily disconnecting the MAF/IAT module.
Last edited by wwest; 08-17-2010 at 08:51 AM.
#22
08-17-2010, 10:03 AM
Re: Pulling the PTU Fuse
Starting in '09 there is a TC ON/OFF switch.
Not saying that I doesn't but I've never seen any extra rear wheel torque while driving on snow on my SG-II. I try to watch where I'm driving so the event can easily be missed! I have seen the the TC icon show that it was active.
Not saying that I doesn't but I've never seen any extra rear wheel torque while driving on snow on my SG-II. I try to watch where I'm driving so the event can easily be missed! I have seen the the TC icon show that it was active.
Last edited by wptski; 08-17-2010 at 03:54 PM.
#23
08-17-2010, 01:32 PM
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Re: Pulling the PTU Fuse
Starting in '09 there is a TC ON/OFF switch.
Not saying that I doesn't but I've never seen any extra rear wheel torque while driving on show on my SG-II. I try to watch where I'm driving so the event can easily be missed! I have seen the the TC icon show that it was active.
Not saying that I doesn't but I've never seen any extra rear wheel torque while driving on show on my SG-II. I try to watch where I'm driving so the event can easily be missed! I have seen the the TC icon show that it was active.
Since there is no way currently to detect that the driveline wouldn't be subject to windup and/or the tires subject to scrubbing the torque coupling to the rear must by default be "fleeting", short term. temporary. At the moment the design only allows rear torque coupling during acceleration whan front tire slip/spin is most lilely to otehrwise occur.
A quite reasonable compromise, all things considered.
While it would be nice, was undoubtedly nice, to have a manual switch that the driver could activate KNOWING that the roadbed is slippery enough to warrant 4WD use, the manufacturers do not wish to have to cover failure claims arsing out of abuse of this feature.
For myself I find it heard to understand why a manual switch with an embedded timeout could not be used. Driver's could activate the switch that would engage rear drive but within a predetermined time period, ~3 minutes(?), the activation would time out.
#24
08-17-2010, 04:02 PM
Re: Pulling the PTU Fuse
There is a 4WD function test where the tech commands 100% rear wheel torque, if it resists turning, it's working properly.
#25
08-17-2010, 05:04 PM
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Re: Pulling the PTU Fuse
It wouldn't come as any surprise to me if TC were disabled above a speed even as low as 20MPH, VSC maybe as high as 50.
IMO neither function operates with much "finesse" so TC or VSC (stability control) activation once higher speeds are attained might "upset" the driving dynamics rather than be helpful.
But how does that pertain to my statement that the rear drive is only engaged during acceleration....? That's what the available documents seem to say plus to do otherwise would severely tax/stress the drive train and increase the wear rate of the tires substantually.
While the documents say that the 4WD system will be engaged anytime wheelspin/slip, FRONT wheelspin/slip, is detected it also says that at this same point TC will intervene and begin controlling the rear clutch duty cycle on its own. If TC is to use the front brakes while simultaneously dethrottling the engine in order to prevent loss of directional control then the rear clutch MUST also be disabled simultaneously.
But you're most likely correct in that it is very unlikely TC would activate in this manner above 62MPH.
So, if you can accelerate hard enough above 60 MPH to result in front wheelspin/slip you would likely get some rear torque apportionment without TC intervention. But good luck with that situation otherwise.
IMO neither function operates with much "finesse" so TC or VSC (stability control) activation once higher speeds are attained might "upset" the driving dynamics rather than be helpful.
But how does that pertain to my statement that the rear drive is only engaged during acceleration....? That's what the available documents seem to say plus to do otherwise would severely tax/stress the drive train and increase the wear rate of the tires substantually.
While the documents say that the 4WD system will be engaged anytime wheelspin/slip, FRONT wheelspin/slip, is detected it also says that at this same point TC will intervene and begin controlling the rear clutch duty cycle on its own. If TC is to use the front brakes while simultaneously dethrottling the engine in order to prevent loss of directional control then the rear clutch MUST also be disabled simultaneously.
But you're most likely correct in that it is very unlikely TC would activate in this manner above 62MPH.
So, if you can accelerate hard enough above 60 MPH to result in front wheelspin/slip you would likely get some rear torque apportionment without TC intervention. But good luck with that situation otherwise.
#26
08-17-2010, 07:52 PM
Re: Pulling the PTU Fuse
It wouldn't come as any surprise to me if TC were disabled above a speed even as low as 20MPH, VSC maybe as high as 50.
IMO neither function operates with much "finesse" so TC or VSC (stability control) activation once higher speeds are attained might "upset" the driving dynamics rather than be helpful.
But how does that pertain to my statement that the rear drive is only engaged during acceleration....? That's what the available documents seem to say plus to do otherwise would severely tax/stress the drive train and increase the wear rate of the tires substantually.
While the documents say that the 4WD system will be engaged anytime wheelspin/slip, FRONT wheelspin/slip, is detected it also says that at this same point TC will intervene and begin controlling the rear clutch duty cycle on its own. If TC is to use the front brakes while simultaneously dethrottling the engine in order to prevent loss of directional control then the rear clutch MUST also be disabled simultaneously.
But you're most likely correct in that it is very unlikely TC would activate in this manner above 62MPH.
So, if you can accelerate hard enough above 60 MPH to result in front wheelspin/slip you would likely get some rear torque apportionment without TC intervention. But good luck with that situation otherwise.
IMO neither function operates with much "finesse" so TC or VSC (stability control) activation once higher speeds are attained might "upset" the driving dynamics rather than be helpful.
But how does that pertain to my statement that the rear drive is only engaged during acceleration....? That's what the available documents seem to say plus to do otherwise would severely tax/stress the drive train and increase the wear rate of the tires substantually.
While the documents say that the 4WD system will be engaged anytime wheelspin/slip, FRONT wheelspin/slip, is detected it also says that at this same point TC will intervene and begin controlling the rear clutch duty cycle on its own. If TC is to use the front brakes while simultaneously dethrottling the engine in order to prevent loss of directional control then the rear clutch MUST also be disabled simultaneously.
But you're most likely correct in that it is very unlikely TC would activate in this manner above 62MPH.
So, if you can accelerate hard enough above 60 MPH to result in front wheelspin/slip you would likely get some rear torque apportionment without TC intervention. But good luck with that situation otherwise.
#27
08-17-2010, 08:35 PM
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Re: Pulling the PTU Fuse
No, the way I read the documentation upon loss of traction at the front, while little or no torque is coupled to the rear, the coupling to the rear will be increased, TC will INSTANTLY begin braking the front wheels so as to quickly sustain a high engine torque level. At the same time this will obviously apportion a higher level of engine torque to the rear. While all this is going on the engine will be FULLY dethrottled both to help lower the potential for loss of directional control, allow the front wheels to regain traction, and prevent the brake rotors from overheating and later warping.
The net result, assuming you're trying to initially get up and going on a slippery surface, is you're stuck in place. Now, if you can disable TC as Toyota was forced to do.....
The net result, assuming you're trying to initially get up and going on a slippery surface, is you're stuck in place. Now, if you can disable TC as Toyota was forced to do.....
Last edited by wwest; 08-17-2010 at 08:38 PM.
#28
08-18-2010, 05:42 AM
Re: Pulling the PTU Fuse
The '07 FE/FEH/MM/MMH didn't have TC. Not sure if TC went into the '08 FE/MM but it was in all '09s.
The following is from the '09 FE/FEH/MM/MMH manual.
Traction Control System
The traction control system is controlled by the ABS module and uses the same wheel speed sensors and tone rings that are used for the anti-lock control system. The ABS module continuously monitors and compares the rotational speed of each wheel and when it detects a wheel spinning excessively, modulates brake pressure to the appropriate brake caliper or wheel cylinder. This is accomplished by opening and closing the appropriate solenoid valves inside the HCU while the hydraulic pump motor is activated. At the same time, the ABS module sends a message over the HS-CAN bus that a traction control event is taking place. When the PCM receives this message, it will assist with traction control by adjusting engine timing and decreasing fuel injector pulses, when the IC receives this message, it will flash the stability/traction control indicator "sliding-car icon". Once the affected wheel returns to normal speed, the ABS module returns the solenoid valves in the HCU to their normal position, deactivates the hydraulic pump motor and sends another message over the HS-CAN bus indicating that the traction event has ended. The PCM returns engine timing and fuel injectors to normal operation and the IC extinguishes the stability/traction control indicator.
Once vehicle speed reaches or exceeds 100 km/h (62 mph), traction control is accomplished only through the PCM.
If the anti-lock control system is disabled due to DTCs being present in the ABS module, the traction control system will also be disabled. When the traction control system is disabled due to DTCs being present, both the ABS warning indicator and the stability/traction control indicator will be illuminated.
Electronic Stability Control (ESC) System
The Electronic Stability Control (ESC) system is controlled by the ABS module and uses the same wheel speed sensors and tone rings that are used for the anti-lock control system. The ESC system also uses input from the steering wheel rotation sensor, the stability control sensors (yaw rate, longitudinal and lateral acceleration) which are internal to the Restraints Control Module (RCM) and information from other modules sent over the HS-CAN bus to help maintain vehicle stability. The ABS module uses all of these inputs to continuously monitor the vehicle direction of travel relative to the driver's intended course. If the ABS module determines from all these inputs that the vehicle is unable to travel in the intended direction, it modulates brake pressure to the appropriate brake caliper(s) or wheel cylinder(s) by opening and closing the appropriate solenoid valves inside the HCU while the hydraulic pump motor is activated. At the same time, the ABS module sends a message over the HS-CAN bus that a stability event is taking place. When the PCM receives this message, it will assist with vehicle stability by adjusting engine timing and decreasing fuel injector pulses. When the IC receives this message, it will flash the stability/traction control indicator "sliding-car icon". Once the stability condition has been corrected, the ABS module returns the solenoid valves in the HCU to their normal position, deactivates the hydraulic pump motor and sends another message over the HS-CAN bus indicating that the event has ended. The PCM returns engine timing and fuel injectors to normal operation and the IC extinguishes the stability/traction control indicator.
If the anti-lock control system is disabled due to DTCs being present in the ABS module, the ESC system will also be disabled. When the ESC system is disabled due to DTCs being present, both the ABS warning indicator and the stability/traction control indicator will be illuminated.
Roll Stability Control (RSCŪ) System
The Roll Stability Control (RSCŪ) system is controlled by the ABS module and uses the same wheel speed sensors and tone rings that are used for the anti-lock control system. The RSCŪ system also uses input from the steering wheel rotation sensor, the stability control sensors (yaw rate, roll rate, longitudinal and lateral acceleration) which are internal to the RCM and information from other modules sent over the HS-CAN bus to help maintain vehicle stability. The ABS module uses all of these inputs to continuously monitor vehicle motion relative to the driver's intended course. If the ABS module determines from all these inputs that conditions exist for a potential roll-over event, it modulates brake pressure to the appropriate brake caliper(s) and wheel cylinder(s) by opening and closing the appropriate solenoid valves inside the HCU while the hydraulic pump motor is activated. At the same time, the ABS module sends a message over the HS-CAN bus that a stability event is taking place. When the PCM receives this message, it will assist with vehicle stability by adjusting engine timing and decreasing fuel injector pulses. When the IC receives this message, it will flash the stability/traction control indicator "sliding-car icon". Once the stability condition has been corrected, the ABS module returns the solenoid valves in the HCU to their normal position, deactivates the hydraulic pump motor and sends another message over the HS-CAN bus indicating that the event has ended. The PCM returns engine timing and fuel injectors to normal operation and the IC extinguishes the stability/traction control indicator.
If the anti-lock control system is disabled due to DTCs being present in the ABS module, the RSCŪ system will also be disabled. When the RSCŪ system is disabled due to DTCs being present, both the ABS warning indicator and the stability/traction control indicator will be illuminated.
Steering Wheel Rotation Sensor
The steering wheel rotation sensor measures the rate of rotation of the steering wheel by monitoring the steering wheel rotation ring as it passes through the sensor gap. The steering wheel rotation sensor uses the HS-CAN bus to transmit information to the ABS module about whether the steering wheel is being turned left or right and how far it is being turned. The steering wheel rotation sensor is integrated into the Electronic Power Assist Steering (EPAS) column assembly and is not serviced separately. For information and diagnostics on the EPAS system, refer to Section 211-00.
Stability/Traction Control Switch
The stability/traction control switch provides the driver with the ability to disable only the traction control feature. Anti-lock control, ESC and RSCŪ systems will remain functional. The switch is hard-wired to the ABS module. When the stability/traction control switch is pressed, a ground signal is sent to the ABS module. The ABS module then sends a message over the HS-CAN bus to the IC indicating that the driver has requested that the system be deactivated and the IC illuminates the stability/traction control indicator "sliding-car icon". The ABS module and the PCM will then ignore any traction events until the driver presses the switch again, the ignition key is cycled or the vehicle speed reaches or exceeds 70 km/h (43 mph). Once the vehicle speed reaches or exceeds 70 km/h (43 mph), the traction control system will re-activate but the indicator will remain illuminated.
Stability/Traction Control Indicator "Sliding-Car Icon"
Status of the traction control, ESC and RSCŪ systems is indicated by a stability/traction control indicator "sliding-car icon" located in the IC. When the driver disables the system through the use of the stability/traction control switch, this indicator will illuminate solidly. When one or more of the systems is currently active, the indicator will flash, and when the system is disabled due to DTCs being present in the ABS module, the indicator will illuminate in conjunction with the yellow ABS warning indicator.
If the systems have been disabled through the stability/traction control switch and the vehicle speed reaches or exceeds 70 km/h (43 mph), the system will activate but the indicator will remain illuminated until the driver presses the switch again or the ignition switch is cycled.
The following is from the '09 FE/FEH/MM/MMH manual.
Traction Control System
The traction control system is controlled by the ABS module and uses the same wheel speed sensors and tone rings that are used for the anti-lock control system. The ABS module continuously monitors and compares the rotational speed of each wheel and when it detects a wheel spinning excessively, modulates brake pressure to the appropriate brake caliper or wheel cylinder. This is accomplished by opening and closing the appropriate solenoid valves inside the HCU while the hydraulic pump motor is activated. At the same time, the ABS module sends a message over the HS-CAN bus that a traction control event is taking place. When the PCM receives this message, it will assist with traction control by adjusting engine timing and decreasing fuel injector pulses, when the IC receives this message, it will flash the stability/traction control indicator "sliding-car icon". Once the affected wheel returns to normal speed, the ABS module returns the solenoid valves in the HCU to their normal position, deactivates the hydraulic pump motor and sends another message over the HS-CAN bus indicating that the traction event has ended. The PCM returns engine timing and fuel injectors to normal operation and the IC extinguishes the stability/traction control indicator.
Once vehicle speed reaches or exceeds 100 km/h (62 mph), traction control is accomplished only through the PCM.
If the anti-lock control system is disabled due to DTCs being present in the ABS module, the traction control system will also be disabled. When the traction control system is disabled due to DTCs being present, both the ABS warning indicator and the stability/traction control indicator will be illuminated.
Electronic Stability Control (ESC) System
The Electronic Stability Control (ESC) system is controlled by the ABS module and uses the same wheel speed sensors and tone rings that are used for the anti-lock control system. The ESC system also uses input from the steering wheel rotation sensor, the stability control sensors (yaw rate, longitudinal and lateral acceleration) which are internal to the Restraints Control Module (RCM) and information from other modules sent over the HS-CAN bus to help maintain vehicle stability. The ABS module uses all of these inputs to continuously monitor the vehicle direction of travel relative to the driver's intended course. If the ABS module determines from all these inputs that the vehicle is unable to travel in the intended direction, it modulates brake pressure to the appropriate brake caliper(s) or wheel cylinder(s) by opening and closing the appropriate solenoid valves inside the HCU while the hydraulic pump motor is activated. At the same time, the ABS module sends a message over the HS-CAN bus that a stability event is taking place. When the PCM receives this message, it will assist with vehicle stability by adjusting engine timing and decreasing fuel injector pulses. When the IC receives this message, it will flash the stability/traction control indicator "sliding-car icon". Once the stability condition has been corrected, the ABS module returns the solenoid valves in the HCU to their normal position, deactivates the hydraulic pump motor and sends another message over the HS-CAN bus indicating that the event has ended. The PCM returns engine timing and fuel injectors to normal operation and the IC extinguishes the stability/traction control indicator.
If the anti-lock control system is disabled due to DTCs being present in the ABS module, the ESC system will also be disabled. When the ESC system is disabled due to DTCs being present, both the ABS warning indicator and the stability/traction control indicator will be illuminated.
Roll Stability Control (RSCŪ) System
The Roll Stability Control (RSCŪ) system is controlled by the ABS module and uses the same wheel speed sensors and tone rings that are used for the anti-lock control system. The RSCŪ system also uses input from the steering wheel rotation sensor, the stability control sensors (yaw rate, roll rate, longitudinal and lateral acceleration) which are internal to the RCM and information from other modules sent over the HS-CAN bus to help maintain vehicle stability. The ABS module uses all of these inputs to continuously monitor vehicle motion relative to the driver's intended course. If the ABS module determines from all these inputs that conditions exist for a potential roll-over event, it modulates brake pressure to the appropriate brake caliper(s) and wheel cylinder(s) by opening and closing the appropriate solenoid valves inside the HCU while the hydraulic pump motor is activated. At the same time, the ABS module sends a message over the HS-CAN bus that a stability event is taking place. When the PCM receives this message, it will assist with vehicle stability by adjusting engine timing and decreasing fuel injector pulses. When the IC receives this message, it will flash the stability/traction control indicator "sliding-car icon". Once the stability condition has been corrected, the ABS module returns the solenoid valves in the HCU to their normal position, deactivates the hydraulic pump motor and sends another message over the HS-CAN bus indicating that the event has ended. The PCM returns engine timing and fuel injectors to normal operation and the IC extinguishes the stability/traction control indicator.
If the anti-lock control system is disabled due to DTCs being present in the ABS module, the RSCŪ system will also be disabled. When the RSCŪ system is disabled due to DTCs being present, both the ABS warning indicator and the stability/traction control indicator will be illuminated.
Steering Wheel Rotation Sensor
The steering wheel rotation sensor measures the rate of rotation of the steering wheel by monitoring the steering wheel rotation ring as it passes through the sensor gap. The steering wheel rotation sensor uses the HS-CAN bus to transmit information to the ABS module about whether the steering wheel is being turned left or right and how far it is being turned. The steering wheel rotation sensor is integrated into the Electronic Power Assist Steering (EPAS) column assembly and is not serviced separately. For information and diagnostics on the EPAS system, refer to Section 211-00.
Stability/Traction Control Switch
The stability/traction control switch provides the driver with the ability to disable only the traction control feature. Anti-lock control, ESC and RSCŪ systems will remain functional. The switch is hard-wired to the ABS module. When the stability/traction control switch is pressed, a ground signal is sent to the ABS module. The ABS module then sends a message over the HS-CAN bus to the IC indicating that the driver has requested that the system be deactivated and the IC illuminates the stability/traction control indicator "sliding-car icon". The ABS module and the PCM will then ignore any traction events until the driver presses the switch again, the ignition key is cycled or the vehicle speed reaches or exceeds 70 km/h (43 mph). Once the vehicle speed reaches or exceeds 70 km/h (43 mph), the traction control system will re-activate but the indicator will remain illuminated.
Stability/Traction Control Indicator "Sliding-Car Icon"
Status of the traction control, ESC and RSCŪ systems is indicated by a stability/traction control indicator "sliding-car icon" located in the IC. When the driver disables the system through the use of the stability/traction control switch, this indicator will illuminate solidly. When one or more of the systems is currently active, the indicator will flash, and when the system is disabled due to DTCs being present in the ABS module, the indicator will illuminate in conjunction with the yellow ABS warning indicator.
If the systems have been disabled through the stability/traction control switch and the vehicle speed reaches or exceeds 70 km/h (43 mph), the system will activate but the indicator will remain illuminated until the driver presses the switch again or the ignition switch is cycled.
#29
08-18-2010, 09:04 AM
Re: Pulling the PTU Fuse
wptski:
You seem to be the man who can gather documentation.
Would you have a wiring schematic of the fuse block in the passenger kick panel? In my '07 MMH, fuse #35 disables both 4x4 and the seat heaters. In later models, fuse #35 controls the 4x4 and the power steering. Following general fuse wiring guidelines, I assume that on the back side of the fuse panel on the output side of fuse #35 is two wires, one for the seat heaters and another for 4x4 in '07 and earlier models and in later models one for power steering and another for 4x4. Basically what I am looking for is the wire color for the 4x4 on this fuse for in both '07 and earlier and '08 and later. Would be an excellent place to wire in a switch with very minimal effort.
You seem to be the man who can gather documentation.
Would you have a wiring schematic of the fuse block in the passenger kick panel? In my '07 MMH, fuse #35 disables both 4x4 and the seat heaters. In later models, fuse #35 controls the 4x4 and the power steering. Following general fuse wiring guidelines, I assume that on the back side of the fuse panel on the output side of fuse #35 is two wires, one for the seat heaters and another for 4x4 in '07 and earlier models and in later models one for power steering and another for 4x4. Basically what I am looking for is the wire color for the 4x4 on this fuse for in both '07 and earlier and '08 and later. Would be an excellent place to wire in a switch with very minimal effort.
#30
08-18-2010, 10:02 AM
Ridiculously Active Enthusiast
Join Date: Sep 2006
Location: Beautiful Pacific NW
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Re: Pulling the PTU Fuse
The '07 FE/FEH/MM/MMH didn't have TC. Not sure if TC went into the '08 FE/MM but it was in all '09s.
The following is from the '09 FE/FEH/MM/MMH manual.
Traction Control System
The traction control system is controlled by the ABS module and uses the same wheel speed sensors and tone rings that are used for the anti-lock control system. The ABS module continuously monitors and compares the rotational speed of each wheel and when it detects a wheel spinning excessively, modulates brake pressure to the appropriate brake caliper or wheel cylinder.
Note: no destinction, "appropriate" brake caliper, left, right, front, rear.
This is accomplished by opening and closing the appropriate solenoid valves inside the HCU while the hydraulic pump motor is activated. At the same time, the ABS module sends a message over the HS-CAN bus that a traction control event is taking place. When the PCM receives this message, it will assist with traction control by adjusting engine timing and decreasing fuel injector pulses,
Note: this statement appears to pertain to pre-DBW systems. With DBW the throttle is simply closed. Prior to DBW, as in my '01 F/awd RX300, the injections were used to "starve" the engine of fuel.
Not saying the FEH doesn't use this method, but if so it's probably a holdover from the days of hard coupled throttles.
when the IC receives this message, it will flash the stability/traction control indicator "sliding-car icon". Once the affected wheel returns to normal speed, the ABS module returns the solenoid valves in the HCU to their normal position, deactivates the hydraulic pump motor and sends another message over the HS-CAN bus indicating that the traction event has ended. The PCM returns engine timing and fuel injectors to normal operation and the IC extinguishes the stability/traction control indicator.
Once vehicle speed reaches or exceeds 100 km/h (62 mph), traction control is accomplished only through the PCM.
If the anti-lock control system is disabled due to DTCs being present in the ABS module, the traction control system will also be disabled. When the traction control system is disabled due to DTCs being present, both the ABS warning indicator and the stability/traction control indicator will be illuminated.
Electronic Stability Control (ESC) System
The Electronic Stability Control (ESC) system is controlled by the ABS module and uses the same wheel speed sensors and tone rings that are used for the anti-lock control system. The ESC system also uses input from the steering wheel rotation sensor, the stability control sensors (yaw rate, longitudinal and lateral acceleration) which are internal to the Restraints Control Module (RCM) and information from other modules sent over the HS-CAN bus to help maintain vehicle stability. The ABS module uses all of these inputs to continuously monitor the vehicle direction of travel relative to the driver's intended course. If the ABS module determines from all these inputs that the vehicle is unable to travel in the intended direction, it modulates brake pressure to the appropriate brake caliper(s) or wheel cylinder(s) by opening and closing the appropriate solenoid valves inside the HCU while the hydraulic pump motor is activated. At the same time, the ABS module sends a message over the HS-CAN bus that a stability event is taking place. When the PCM receives this message, it will assist with vehicle stability by adjusting engine timing and decreasing fuel injector pulses. When the IC receives this message, it will flash the stability/traction control indicator "sliding-car icon". Once the stability condition has been corrected, the ABS module returns the solenoid valves in the HCU to their normal position, deactivates the hydraulic pump motor and sends another message over the HS-CAN bus indicating that the event has ended. The PCM returns engine timing and fuel injectors to normal operation and the IC extinguishes the stability/traction control indicator.
If the anti-lock control system is disabled due to DTCs being present in the ABS module, the ESC system will also be disabled. When the ESC system is disabled due to DTCs being present, both the ABS warning indicator and the stability/traction control indicator will be illuminated.
Roll Stability Control (RSCŪ) System
The Roll Stability Control (RSCŪ) system is controlled by the ABS module and uses the same wheel speed sensors and tone rings that are used for the anti-lock control system. The RSCŪ system also uses input from the steering wheel rotation sensor, the stability control sensors (yaw rate, roll rate, longitudinal and lateral acceleration) which are internal to the RCM and information from other modules sent over the HS-CAN bus to help maintain vehicle stability. The ABS module uses all of these inputs to continuously monitor vehicle motion relative to the driver's intended course. If the ABS module determines from all these inputs that conditions exist for a potential roll-over event, it modulates brake pressure to the appropriate brake caliper(s) and wheel cylinder(s) by opening and closing the appropriate solenoid valves inside the HCU while the hydraulic pump motor is activated. At the same time, the ABS module sends a message over the HS-CAN bus that a stability event is taking place. When the PCM receives this message, it will assist with vehicle stability by adjusting engine timing and decreasing fuel injector pulses. When the IC receives this message, it will flash the stability/traction control indicator "sliding-car icon". Once the stability condition has been corrected, the ABS module returns the solenoid valves in the HCU to their normal position, deactivates the hydraulic pump motor and sends another message over the HS-CAN bus indicating that the event has ended. The PCM returns engine timing and fuel injectors to normal operation and the IC extinguishes the stability/traction control indicator.
If the anti-lock control system is disabled due to DTCs being present in the ABS module, the RSCŪ system will also be disabled. When the RSCŪ system is disabled due to DTCs being present, both the ABS warning indicator and the stability/traction control indicator will be illuminated.
Steering Wheel Rotation Sensor
The steering wheel rotation sensor measures the rate of rotation of the steering wheel by monitoring the steering wheel rotation ring as it passes through the sensor gap. The steering wheel rotation sensor uses the HS-CAN bus to transmit information to the ABS module about whether the steering wheel is being turned left or right and how far it is being turned. The steering wheel rotation sensor is integrated into the Electronic Power Assist Steering (EPAS) column assembly and is not serviced separately. For information and diagnostics on the EPAS system, refer to Section 211-00.
Stability/Traction Control Switch
The stability/traction control switch provides the driver with the ability to disable only the traction control feature. Anti-lock control, ESC and RSCŪ systems will remain functional. The switch is hard-wired to the ABS module. When the stability/traction control switch is pressed, a ground signal is sent to the ABS module. The ABS module then sends a message over the HS-CAN bus to the IC indicating that the driver has requested that the system be deactivated and the IC illuminates the stability/traction control indicator "sliding-car icon". The ABS module and the PCM will then ignore any traction events until the driver presses the switch again, the ignition key is cycled or the vehicle speed reaches or exceeds 70 km/h (43 mph). Once the vehicle speed reaches or exceeds 70 km/h (43 mph), the traction control system will re-activate but the indicator will remain illuminated.
Stability/Traction Control Indicator "Sliding-Car Icon"
Status of the traction control, ESC and RSCŪ systems is indicated by a stability/traction control indicator "sliding-car icon" located in the IC. When the driver disables the system through the use of the stability/traction control switch, this indicator will illuminate solidly. When one or more of the systems is currently active, the indicator will flash, and when the system is disabled due to DTCs being present in the ABS module, the indicator will illuminate in conjunction with the yellow ABS warning indicator.
If the systems have been disabled through the stability/traction control switch and the vehicle speed reaches or exceeds 70 km/h (43 mph), the system will activate but the indicator will remain illuminated until the driver presses the switch again or the ignition switch is cycled.
The following is from the '09 FE/FEH/MM/MMH manual.
Traction Control System
The traction control system is controlled by the ABS module and uses the same wheel speed sensors and tone rings that are used for the anti-lock control system. The ABS module continuously monitors and compares the rotational speed of each wheel and when it detects a wheel spinning excessively, modulates brake pressure to the appropriate brake caliper or wheel cylinder.
Note: no destinction, "appropriate" brake caliper, left, right, front, rear.
This is accomplished by opening and closing the appropriate solenoid valves inside the HCU while the hydraulic pump motor is activated. At the same time, the ABS module sends a message over the HS-CAN bus that a traction control event is taking place. When the PCM receives this message, it will assist with traction control by adjusting engine timing and decreasing fuel injector pulses,
Note: this statement appears to pertain to pre-DBW systems. With DBW the throttle is simply closed. Prior to DBW, as in my '01 F/awd RX300, the injections were used to "starve" the engine of fuel.
Not saying the FEH doesn't use this method, but if so it's probably a holdover from the days of hard coupled throttles.
when the IC receives this message, it will flash the stability/traction control indicator "sliding-car icon". Once the affected wheel returns to normal speed, the ABS module returns the solenoid valves in the HCU to their normal position, deactivates the hydraulic pump motor and sends another message over the HS-CAN bus indicating that the traction event has ended. The PCM returns engine timing and fuel injectors to normal operation and the IC extinguishes the stability/traction control indicator.
Once vehicle speed reaches or exceeds 100 km/h (62 mph), traction control is accomplished only through the PCM.
If the anti-lock control system is disabled due to DTCs being present in the ABS module, the traction control system will also be disabled. When the traction control system is disabled due to DTCs being present, both the ABS warning indicator and the stability/traction control indicator will be illuminated.
Electronic Stability Control (ESC) System
The Electronic Stability Control (ESC) system is controlled by the ABS module and uses the same wheel speed sensors and tone rings that are used for the anti-lock control system. The ESC system also uses input from the steering wheel rotation sensor, the stability control sensors (yaw rate, longitudinal and lateral acceleration) which are internal to the Restraints Control Module (RCM) and information from other modules sent over the HS-CAN bus to help maintain vehicle stability. The ABS module uses all of these inputs to continuously monitor the vehicle direction of travel relative to the driver's intended course. If the ABS module determines from all these inputs that the vehicle is unable to travel in the intended direction, it modulates brake pressure to the appropriate brake caliper(s) or wheel cylinder(s) by opening and closing the appropriate solenoid valves inside the HCU while the hydraulic pump motor is activated. At the same time, the ABS module sends a message over the HS-CAN bus that a stability event is taking place. When the PCM receives this message, it will assist with vehicle stability by adjusting engine timing and decreasing fuel injector pulses. When the IC receives this message, it will flash the stability/traction control indicator "sliding-car icon". Once the stability condition has been corrected, the ABS module returns the solenoid valves in the HCU to their normal position, deactivates the hydraulic pump motor and sends another message over the HS-CAN bus indicating that the event has ended. The PCM returns engine timing and fuel injectors to normal operation and the IC extinguishes the stability/traction control indicator.
If the anti-lock control system is disabled due to DTCs being present in the ABS module, the ESC system will also be disabled. When the ESC system is disabled due to DTCs being present, both the ABS warning indicator and the stability/traction control indicator will be illuminated.
Roll Stability Control (RSCŪ) System
The Roll Stability Control (RSCŪ) system is controlled by the ABS module and uses the same wheel speed sensors and tone rings that are used for the anti-lock control system. The RSCŪ system also uses input from the steering wheel rotation sensor, the stability control sensors (yaw rate, roll rate, longitudinal and lateral acceleration) which are internal to the RCM and information from other modules sent over the HS-CAN bus to help maintain vehicle stability. The ABS module uses all of these inputs to continuously monitor vehicle motion relative to the driver's intended course. If the ABS module determines from all these inputs that conditions exist for a potential roll-over event, it modulates brake pressure to the appropriate brake caliper(s) and wheel cylinder(s) by opening and closing the appropriate solenoid valves inside the HCU while the hydraulic pump motor is activated. At the same time, the ABS module sends a message over the HS-CAN bus that a stability event is taking place. When the PCM receives this message, it will assist with vehicle stability by adjusting engine timing and decreasing fuel injector pulses. When the IC receives this message, it will flash the stability/traction control indicator "sliding-car icon". Once the stability condition has been corrected, the ABS module returns the solenoid valves in the HCU to their normal position, deactivates the hydraulic pump motor and sends another message over the HS-CAN bus indicating that the event has ended. The PCM returns engine timing and fuel injectors to normal operation and the IC extinguishes the stability/traction control indicator.
If the anti-lock control system is disabled due to DTCs being present in the ABS module, the RSCŪ system will also be disabled. When the RSCŪ system is disabled due to DTCs being present, both the ABS warning indicator and the stability/traction control indicator will be illuminated.
Steering Wheel Rotation Sensor
The steering wheel rotation sensor measures the rate of rotation of the steering wheel by monitoring the steering wheel rotation ring as it passes through the sensor gap. The steering wheel rotation sensor uses the HS-CAN bus to transmit information to the ABS module about whether the steering wheel is being turned left or right and how far it is being turned. The steering wheel rotation sensor is integrated into the Electronic Power Assist Steering (EPAS) column assembly and is not serviced separately. For information and diagnostics on the EPAS system, refer to Section 211-00.
Stability/Traction Control Switch
The stability/traction control switch provides the driver with the ability to disable only the traction control feature. Anti-lock control, ESC and RSCŪ systems will remain functional. The switch is hard-wired to the ABS module. When the stability/traction control switch is pressed, a ground signal is sent to the ABS module. The ABS module then sends a message over the HS-CAN bus to the IC indicating that the driver has requested that the system be deactivated and the IC illuminates the stability/traction control indicator "sliding-car icon". The ABS module and the PCM will then ignore any traction events until the driver presses the switch again, the ignition key is cycled or the vehicle speed reaches or exceeds 70 km/h (43 mph). Once the vehicle speed reaches or exceeds 70 km/h (43 mph), the traction control system will re-activate but the indicator will remain illuminated.
Stability/Traction Control Indicator "Sliding-Car Icon"
Status of the traction control, ESC and RSCŪ systems is indicated by a stability/traction control indicator "sliding-car icon" located in the IC. When the driver disables the system through the use of the stability/traction control switch, this indicator will illuminate solidly. When one or more of the systems is currently active, the indicator will flash, and when the system is disabled due to DTCs being present in the ABS module, the indicator will illuminate in conjunction with the yellow ABS warning indicator.
If the systems have been disabled through the stability/traction control switch and the vehicle speed reaches or exceeds 70 km/h (43 mph), the system will activate but the indicator will remain illuminated until the driver presses the switch again or the ignition switch is cycled.
The important thing to keep in mind, remember, IMO, is that these are base FWD vehicles. Upon detection of loss of traction on the front wheels due to engine torque, leading or lagging (engine compression braking), and in the FEH case possibly due to regen braking only at the front, nothiong less than EXTREME meassures must be made to most quickly restore front wheel/tire traction.
That's why these FWD & F/awd vehicles are now equipped with a TC off function switch. Without the ability to switch off the TC functionality it is designed to be so agressive in restoring front traction that oftentimes you end up stuck in place.
