Trac And Abs Light On When Temp Cold

[tds]

Hi,

I would really appreciate it if anyone can help me solve this problem:

I have a 1991 LS400 and am having a problem with the TRAC and ABS dash lights coming on, but only when the temperature is at or around freezing (i.e. less than around 35 deg F). You can see the dash lights on in the attached file (engine is running).

When the these dash lights are on, the traction control does not work (i.e. one rear wheel spins) and the ABS does not work (brakes still work, but ABS does not).

This happened last winter and the dealer tried his best to fix it (details below), but he was unable to. The problem went away when it got warmer (I'm from Toronto in Canada), but is now back again with the colder weather.

Sometimes if I stop and restart the engine the lights will go out. Other times this fails and I must drive the car for 15 - 20 minutes, and then if I stop and restart it, the lights will go out (there does not seem to be any pattern except that the colder it gets, the worse the problem).

Here is what has been done to date to fix this problem:

1. Dec 17, 2002: Dealer found engine codes 41 (TPS signal ... Throttle Positioning Sensor), Trac code 19 (Trac motor over use), 45 (main TPS operation) and 51 (Engine control malfunction). The TPS sensor was replaced and the TRAC light and ABS light were not apparent after the roadtest, but the problem reappeared a few days later.

2. Dec 30, 2002: The dealer checked for engine codes, but found that it was not possible to communicate with the ECU (i.e. ABS computer). The dealer quoted me $1,307.00 + Taxes for a new ABS computer. I said no way!!! and purchased a used one from a wrecker for $200.00.

3. Jan 11, 2003: The dealer installs the used ABS computer, tests it and the ABS computer is now working (i.e. can communicate with the ABS computer). The relay on the used computer was defective, so they used the existing relay. The temperature warmed up and they were not able to test the repair. Later, the temperature got colder and the problem reappeared.

4. March 1, 2003: The dealer ordered a new computer relay to replace the original one.

This did not fix the car and now that the weather has turned cold again, the problem is back. I would really appreciate any help I can get (the LS400 is a great car, but it really does need traction control in the snow :)

Thanks in advance

Dan

[90LS400Lexus]

Sorry I do not know the answer to your problem, but I noticed something interesting. My car reads "ANTILOCK", where yours reads "ABS". My car is a 90, which is the same car. Did they already make this change only after a year, or is it possibly because your car has "KPH" instead of "MPH". Perhaps that was an additional difference in the cluster.

Good luck.

[tds]

Hi and thanks for the feedback.

I am in Canada and there are some superficial differences between the cars sold in the US and in Canada.

On my car the speedometer reads in KPH (i.e. kilometers per hour) with MPH in smaller numbers on the KPH scale. Also, US cars will read ANTILOCK while Canadian cars will read ABS (i.e. Antilock Braking System). Otherwise the cars are essentially identical.

Regards

Dan

[wwest]

The ABS pumpmotor runs on 12 volt DC and there is a really good chance that the motor brushes are now worn to the point that they do not quite contact the commutator when COLD. Each time you apply the brakes the ABS ecu checks for brake fluid pressure in the accummulator and if it is low it starts the pumpmotor to replenish the pressure.

[tds]

Thanks wwest. I will have my dealer check it out. It would be nice if this the fix for the problem as I love the car, but it really does need the traction control in snow.

Dan

[wwest]

Actually, the few times I have had it activate I mostly found it to a nuisance. But it does often serve to tell me I'm traveling on a slick surface and therefore I know to use the throttle lightly.

And please remember the primary purpose of ABS is to allow you to maintain directional control during severe braking. While it will sometimes help you stop in a shorter distance on a rain slicked surface in the majority of cases it will actually elongate your stopping distance in favor of giving you the ability for directional control.

IMMHO future Anti-lock systems will only activate if the VSC yaw sensor indicates that the vehicle is not following the correct "line".

ABS can be of great help, but I always disable mine during the summer months.

[LinuxFan]

Was there any consensus on this issue? It seems this bug has bit me also on the same model year vehicle.

thanks