Is there a hack to manually turn on 4wd-i (or to take the not so intelligent "i" out of 4wd-i)?

I've read the cons of 4wd-i and have shared similar bad experiences. I live in New England and have a steep driveway and a steep hill nearby. In moderate snow accumulation, I cannot reliably make it up either in my 08 HyHi. (My other car is an AWD Subaru, which has never had a problem ... well, except for the one time my wife repeatedly tried to make it up the driveway in the HyHi first and flattened all the snow into slippery sheets of ice, so there was zero traction ... ) I've taken to parking at a neighbors and waiting for the plow or manually clearing my driveway first, which defeats the purpose of the supposed 4wd.

What I'm wondering is if anyone has successfully modified/hacked a HyHi (or even just heard about a way to do it) such that I could install a switch that would allow me to manually turn on the 4wd-i system. I assume that if the car thinks the front tires were already spinning and/or thought the rear tires were spinning so it would act more like a traditional linked AWD car and allow me to inch up the hill. Clearly, I wouldn't want to drive a long distance or at a high speed with this, but I'd love to be able to slowly crawl up my hills.

 

Since the HH is primarily FWD there is really no way.

FWD vehicles are especially HAZARDOUS in wintertime slippery road conditions. Remember that if/when those front drive wheels begin slipping/spinning due to the use of too much engine torque for road conditions you have also..

LOST DIRECTIONAL CONTROL OF THE VEHICLE.

So special TC, Traction Control, design efforts are being made to quickly bring the vehicle back under full control once even the slightest wheelspin/slip is detected. So yes, the rear drive will INSTANTLY be brought online with the detection of front wheelspin/slip. But at the same time, for reasons of safety, the overall HSD drive capability will be so severely "dethrottled" the vehicle will not readily move forward.

Perhaps in the near future Toyota will adopt the Ford Escape and Mercury Mariner hybrid F/awd system for the RXh and HH as it has just done for the Venza, Sienna, and 2010 RX350.

The 2010 RX350 F/awd system has a manual switch that can be used to engage the rear drive coupling clutch and put the system in the part-time 4Wd mode. Apparently the Venza and Sienna owners were judged not to be trusted with this capability.

 

I experimented with this idea/concept with a friend's RXh. Around here on the Seattle eastside a truly functional AWD system can often make the difference between getting home or sleeping on the office floor.

I had figured that if I could "simulate" front wheelspin/slip when it actually was not then the 4wd-i system would automatically "engage" some/more RWD. So we developed a microprocessor module that watched for the depression of the gas pedal and automatically switched in an electronic circuit that substituted a "accelerated" (simulated slight "overspeed") front wheel ABS speed sensor signal for the real signal.

But what we discovered was that the TC system caused the HSD system to instantly go into full "dethrotte" mode so it didn't matter if the rear drive became active.

Frustrating.

 

See this thread for directions to turn off the 4wd-i system;

http://www.toyotanation.com/forum/sh...d.php?t=333787

It is not a fix for getting you up your driveway however, the fix for that is to get snow tires. With snow tires, the HH is very capable in snow/ice.

 

Snow tires are virtually USELESS on hard packed snow or ice. Summer tires, with more CSA contact surface, will almost always work better. My compromise is to use summer tires all year around supplemented by tire chains as/when needed.

Upon reading the stuff over at ToyotaNation it appears that there are several ways of disabling TC on the HH. But since TC is also the controlling factor for bringing rear drive on-line it appears that with TC disabled you're left with a simple FWD vehicle.

The Ford F/awd system, hybrid and non, has much the same problem. upon detection of front drive wheelspin/slip the rear drive is engaged but the engine/drive is simultaneously dethrottled at the same time.

Other than pre-emptive use of rear drive coupling during low speed acceleration to help lower the potential for wheelspin/slip of just what good did the engineers expect these systems to be...??

It is clear to me that a manual rear drive engagement switch is needed for certain situations. But then how would the engineers go about preventing misuse, inadvertent or otherwise, and thereby damaging the drive train..??

At one time Ford was using a thermistor to detect rising temperatures in the rear drive coupling clutch system with a warning to drivers to stop using the system if the warning light came on. Obviously too many driver's ignored the warning because the manual engagement capability was discontinued.

I guess we'll have to wait and see if the RX350 still has a switch a year from now. I'd bet not.

 

Complete B.S. I live in an region (Alaska) where there is snow and ice on the roads for better part of 7 months months of the year and can definitivly say that is really dumb advice for contending with with ice and snow. Modern winter tires with soft sticky rubber compond and deep tread siping make a huge difference in driving on ice and hardpack snow. There are numerous tire comparison test that have been done for winter tires. I challenge you show a single test that has a summer tire beating a Blizzak or Hakkapulita winter tire for acceleration time or stopping distance on ice.

The "secret" to getting a Highland Hybrid to go well on snow/ice is that you need enought traction that you dont get so much wheelspin as to cause the traction control throttle shutdown situation. This wont be the case if you are using summer tires on icy conditions.

 

Sorry, I have to refuse the challenge. Winter tire marketeers. snake oil salespersons, ALL, aren't stupid enough to show those results. But let me reverse the "challenge", if I may.

Show me a comparison test of winter tires vs summer, or even one winter tire against another, that isn't done on a roadway surface with lots of loose snow to "throw" about, and you win the challenge.

It's been many years since I had to drive a car in the winter in Anchorage or Fairbanks, but I seem to remember that it was quite rare to find any roadway with freshly fallen "loose" stuff, mostly either well packed down snow or hard frozen ice.

I'd bet you're using studded winter tires...

 

Yes, GREAT "FIX"...!!

NOT..!!

Turns off rear drive altogether leaving you with TC'less FWD. No rear drive and patently unsafe to boot.

*****en' problem, pay extra for that 75HP rear electric motor that has no practical use.

Does one of the front MG's have an over-temperature monitor..??

If so maybe it could be modified to indicate being so close to overtemp that the rear drive is used to compensate.

 

Yeah, WWest, I'm going to have to call BS on your winter/summer tire claims. I live in MN and we get plenty of snow and sub-zero temps. I'm a generally lazy individual, and procrastinate switching the summer tires on our '06 HiHy out for the winter ones until the first snows. Absolutely a world of difference between the two, yes, even on packed snow or ice.

Consumer Reports does comparison testing on tires, and clearly shows a difference between summer, all-weather, and dedicated winter tires. And if you think that Consumer Reports has a bias (paid off by the tire mfg), then there's no reasoning with you.

 

I'm not saying that winter specialty tires are of no use, usefullness, just that in the big picture I believe many drivers would be better off the majority of the time, wintertime, riding on nice and quiet, more comfortably riding, summer tires.

I hate the sound, and the EXPENSE to the city/state (that would be US..!!), of studded tires on a highly tractive roadbed.