BACK...To the FUTURE...
#11
08-31-2010, 12:16 PM
Join Date: Sep 2006
Location: Beautiful Pacific NW
Posts: 1,678
Re: BACK...To the FUTURE...
If so, there's nothing in the owner's manual about this. In the Workshop manual it states to let the vehicle idle for ten minutes for cooling.
The manual states that the ATC goes into 100% locked mode till it cools
The historical information, early FE, indicates that even at 100% locked there may be instances wherein the temperature level of the ATC lubricating oil might continue to rise.
100% "locked". 50/50 torque distribution F/R using a wet clutch does not of necessaty indicate 100% "locked", FULLY LOCKED.
but there's no temperature sensor in the rearend, so how does it detect this?
I suspect the calculation is based on knowing the OAT, the roadspeed, the engine torque output, and the running average of the differential rotation rate of the rear driveline vs the front driveline.
Further more with a full 100% locked mode would cause steering control problems.
If one were truly "off-road", and experienced at same, that would be fully expected. But again I strongly suspect that 100% locked does not mean no rear clutch slippage. Otherwise why would a "means" be provided if/when the temperature continues to rise.
The manual states that the ATC goes into 100% locked mode till it cools
The historical information, early FE, indicates that even at 100% locked there may be instances wherein the temperature level of the ATC lubricating oil might continue to rise.
100% "locked". 50/50 torque distribution F/R using a wet clutch does not of necessaty indicate 100% "locked", FULLY LOCKED.
but there's no temperature sensor in the rearend, so how does it detect this?
I suspect the calculation is based on knowing the OAT, the roadspeed, the engine torque output, and the running average of the differential rotation rate of the rear driveline vs the front driveline.
Further more with a full 100% locked mode would cause steering control problems.
If one were truly "off-road", and experienced at same, that would be fully expected. But again I strongly suspect that 100% locked does not mean no rear clutch slippage. Otherwise why would a "means" be provided if/when the temperature continues to rise.
#12
08-31-2010, 01:38 PM
Re: BACK...To the FUTURE...
Sounds like a lot of calculating only to say that somethng should be or shouldn't be overheated where a sensor would say for sure.
This is all the '09 FE/FEH Workshop Manual says about the ATC temperature.
Heat Protection Mode
During very extreme off-road operation, the AWD system utilizes a heat protection mode to protect the ATC solenoid (part of rear axle) from damage. If the system detects an overheat condition, it enters a locked mode. If the heat in the system continues to rise once in the locked mode, the 4X4 control module disables the ATC solenoid. Allow the system to cool down at least 10 minutes with the ignition switch in the ON position.
This is all the '09 FE/FEH Workshop Manual says about the ATC temperature.
Heat Protection Mode
During very extreme off-road operation, the AWD system utilizes a heat protection mode to protect the ATC solenoid (part of rear axle) from damage. If the system detects an overheat condition, it enters a locked mode. If the heat in the system continues to rise once in the locked mode, the 4X4 control module disables the ATC solenoid. Allow the system to cool down at least 10 minutes with the ignition switch in the ON position.
#13
08-31-2010, 02:15 PM
Join Date: Sep 2006
Location: Beautiful Pacific NW
Posts: 1,678
Re: BACK...To the FUTURE...
Sounds like a lot of calculating only to say that somethng should be or shouldn't be overheated where a sensor would say for sure.
This is all the '09 FE/FEH Workshop Manual says about the ATC temperature.
Heat Protection Mode
During very extreme off-road operation, the AWD system utilizes a heat protection mode to protect the ATC solenoid (part of rear axle) from damage. If the system detects an overheat condition, it enters a locked mode. If the heat in the system continues to rise once in the locked mode, the 4X4 control module disables the ATC solenoid. Allow the system to cool down at least 10 minutes with the ignition switch in the ON position.
This is all the '09 FE/FEH Workshop Manual says about the ATC temperature.
Heat Protection Mode
During very extreme off-road operation, the AWD system utilizes a heat protection mode to protect the ATC solenoid (part of rear axle) from damage. If the system detects an overheat condition, it enters a locked mode. If the heat in the system continues to rise once in the locked mode, the 4X4 control module disables the ATC solenoid. Allow the system to cool down at least 10 minutes with the ignition switch in the ON position.
"..protect the ATC solenoid.."
Verbatim wording..?
Seems odd...
#15
08-31-2010, 03:57 PM
Re: BACK...To the FUTURE...
No chassis ground, a floating ground is used. I know this for sure.
#17
09-01-2010, 05:56 AM
Re: BACK...To the FUTURE...
The solenoid draws less than 1A. The manual states that it is <5 ohms. There are no DTCs listed for temperature or for current either.
#18
09-01-2010, 06:42 AM
Join Date: Sep 2006
Location: Beautiful Pacific NW
Posts: 1,678
Re: BACK...To the FUTURE...
<5 ohms might be 4 ohms, I = E/R, 12/4 = 3A
Don't know if this will correlate with the FE(H), certainly not directly so, but the 2011 F/awd RX350 specifications are: 2.2 to 2.6 ohms for the ATC solenoid but DTC 1298 if the current exceeds 0.8 amps for one second or more. Looks like a peak current of ~5 amps but with a duty-cycle of less 20%.
Don't know if this will correlate with the FE(H), certainly not directly so, but the 2011 F/awd RX350 specifications are: 2.2 to 2.6 ohms for the ATC solenoid but DTC 1298 if the current exceeds 0.8 amps for one second or more. Looks like a peak current of ~5 amps but with a duty-cycle of less 20%.
Last edited by wwest; 09-01-2010 at 07:04 AM.
#19
09-01-2010, 07:04 AM
Re: BACK...To the FUTURE...
I've monitored the 4WD module's voltage/current output with a scope. Always less than 1A nomatter what the duty cycle was. I didn't check the solenoid's resistance but some test points state 2-5 ohms.
Wondering why they refer to it as a solenoid anyway?
Wondering why they refer to it as a solenoid anyway?
#20
09-01-2010, 04:14 PM
Join Date: Sep 2006
Location: Beautiful Pacific NW
Posts: 1,678
Re: BACK...To the FUTURE...
Because it really is a simple "actuated or not" solenoid.
Some years ago now automotive engineers discovered that standard, PLAIN, off the shelf Bang-Bang, on or off, servo control action solenoids could be used in a linear fashion with PWM and deterministic "downstream" feedback logic.
I think the throttle fully closed idle airflow bypass was the first wifespread use. The idle "target", ~800RPM, could be determined easily enough and the only other feedback required was the upstream oxygen sensor. Unplug the battery on one of these, say my 2.3L '93 Ford Ranger PU, to wipe the "learned" parameters and now restart it and it would quickly learn, starting from the factory default/approximation parameters, the correct EFI & idle air bypass solenoid PWM dutycycle to sustain 800 RPM and no oxygen in the exhaust.
The "feedback" in this case, F/awd, is the difference between front driveline rotation rate and rear driveline rotation rate. If the control system for some reason needs to find, learn, the correct PWM dutycycle to attain a 50/50 torque split at a specific engine torque level all it has to do is keep raising the dutycycle until the rear an front drivelines are rotating at the same rate.
Some years ago now automotive engineers discovered that standard, PLAIN, off the shelf Bang-Bang, on or off, servo control action solenoids could be used in a linear fashion with PWM and deterministic "downstream" feedback logic.
I think the throttle fully closed idle airflow bypass was the first wifespread use. The idle "target", ~800RPM, could be determined easily enough and the only other feedback required was the upstream oxygen sensor. Unplug the battery on one of these, say my 2.3L '93 Ford Ranger PU, to wipe the "learned" parameters and now restart it and it would quickly learn, starting from the factory default/approximation parameters, the correct EFI & idle air bypass solenoid PWM dutycycle to sustain 800 RPM and no oxygen in the exhaust.
The "feedback" in this case, F/awd, is the difference between front driveline rotation rate and rear driveline rotation rate. If the control system for some reason needs to find, learn, the correct PWM dutycycle to attain a 50/50 torque split at a specific engine torque level all it has to do is keep raising the dutycycle until the rear an front drivelines are rotating at the same rate.
