Curt

My 1990 LS400 got stuck a few weeks ago. I parked on the street, with my right tires in the snowbank. When I tried to pull out, the car wouldn't go, even with the left tire on dry pavement. The left tire wasn't turning. I was able to back out, but I really wanted the traction control to push me out. A week later I parked in exactly the same spot and had exactly the same problem. A few days after that I pulled up to a snowbank on the left side of the car and was able to push right through it.

I think my traction control is working on the right side of the car (i.e., the right tire will spin slowly), but not on the left side (the left tire doesn't push).

My traction control switch and light seem to be working properly. When I switch it off, I can burn rubber, but when it's on, it does a great job keeping the RPM's down. Also, I can hear the creaking noise when the traction control is working. I think it sounds like an old submarine submerging.

So what things could cause my symptoms?

Would air in the right rear brake line do this? Perhaps that would keep the system from applying enough pressure to the right brake, so the left tire never gets power.

Or could there be something wrong in the traction components under the hood?

Or could it be a fuse or something?

What else could be my problem?

Thanks for all your help.
Curt

aliga

iTrader: (147)

one one wheel turns, your car does not have a lsd.

HarrierAWD

To get unstuck from snow, you actually have to turn OFF the traction control. Try that next time.

Curt

Okay, I'll try it, but it doesn't make sense to me. Why would that help?

Okay, so what is an LSD? A search through the forums implies that it has to do with the gearing. People are talking about it with a TC (possibly that means torque converter?) So maybe LSD is a limited slip differential. If that's the case, it was my understanding that no Lexus has that (although I think some 4Runners or Land Cruisers had it). But I have traction control instead, which is far superior to a limited slip differential.

I think that the brake is not getting applied (or not enough) to the right rear wheel. But I'm not sure what things might cause that to happen.

I have the service manual, and it has about 80 pages covering the traction control system. But it's not very user-friendly for a shade-tree mechanic like me. Most of it is talking about the error codes, but my TRAC OFF light isn't coming on when I don't want it to, so I don't think the system has sensed an error.

I'm thinking about trying to put a scale on the garage wall, park the car so it sandwiches the scale between the car and the wall, then jack up one rear wheel and see how many pounds of force I have. Then if I do it on the other side I'll be able to measure this scientifically. Then I could turn it around and try it in reverse. Ideally, I'd like to see all four setups have similar force. There are two problems I see:
1. I might need a pretty hefty scale (maybe 500 lbs or so)
2. I need the frame of the car to push the scale, not the bumper push the scale

Maybe instead of a scale, I could hook up a pully to lift a measured weight.

But even if I scientifically test to verify that the problem is real, I still need to fix it, and that means I need to know what is wrong with the system. Any ideas?

Curt