Trac Light 92 Ls 400

[amphora]

This is my first post....My trac light comes and goes without any connection to road condition...lately it has just stayed on and the only way to get it to turn off is to restart car...I even turned off the TRAC OFF button and it stays off ! How worried should I be....how bad is this ? Thank you for any help, ideas.

[VMF]

you should be slightyly worried:) what you should do now is get the error codes while light is on and that will tell you what exactly is wrong and THEN:) you will know if you have to worry or not. there is a special procedure how to get those codes out of your car since genI has been changed in 92 or 93. but i'm sure one of the 92 guys here will tell you exaclty what to do once he will get his eyes on this post

[jzz30]

i had the same problem and i couldnt figure out what the problem was so i was forced to take it to the dealer and after $80 of lablor+ $2.50 parts guess what it was............it was a fuse well still dont know why a fuse would blow but well it hasnt come back and that was about a year ago so i guess its ok so my suggestion is to try and check your fuse

[mobilyte]

message deleted

[wwest]

"had the same problem two years ago...."

No, you had check engien AND trac failure indications. Trac is always disabled automatically, resulting in the indication, on any engine diagnostic check.

Trac indication ALONE....:

Each time you apply the brakes the ABS ecu checks for accumulator hydraulic pressure and if it's low, restarts the ABS/Trac pumpmotor to build it back up again. If it finds the pressure low ten times in a row, ten sequential applications of the brakes, it illuminates the fualt indication on the theory that for some reason the system is no able to hold, sustain, the brake hydraulic pressure even with a backup accumulator nitrogen pressurized to 3000PSI.

If I remember the system plumbing correctly the Trac system will no longer function at all but ABS will.

For a sensible driver Tarc is useless anyway. Trac is only for the idiot drivers taht don't have the good sense to get off the gas when a tire slips and then reapply moderately, feathering the throttle to get the vehicle initially moving.

On the 92 LS Trac will instantly apply both rear brakes with slippage and just as quickly dethrottle the engine.

Useless.

[wwest]

Thank you for this very useful information...should I then be concerned as to why the accumulator hydrolic pressure is not sustaining pressure ?  If I do choose to ignore the TRAC feature, can this decrease in pressure lead to any other problems ?  Very good to hear this does not decrease the effectiveness of the ABS !  Thank you for your help.

I would most certainly have someone have a look at it and it is possible that a full and complete** brake fluid flushing would clear any debris that might be around blocking a check valve.

*** Several extra bleed valves inside the engine compartment.

[91ls400]

My 91 ls400 has a similar problem with the trac light. If it is a bad oxygen sensor how can i test this. How can i get the error codes for the trac system, do I need to take it to a lexus dealer, does a toyota dealer have the necessary equipment to figure out the problem? When my trac light comes on the traction control is lost but I still have anti-lock brakes!

[UCF3]

You can take your car to any service station-Goodyear service, toyota and honda, since the code readers they use are universal.

I would suggest, visiting a good shop that carries the more expensive code readers, but be aware, their charges can be expensive.

Keep us in the loop once you find out what's wrong with it.

[VMF]

you dont even have to go to any store. just go for the autozone and rent the tool. its FREE!!!!! write down the error codes and then post them here. a lot of us have lists of those error codes with explanations and instructions on how to fix or do more troubleshooting.

[Zdeno]

I have 1991 LS 400. I read all bills from original owner and found -

LABOR

- Diagnosis Traction ControlSystem, the reason for the TRAC-CONROL Light being on at times

- Checked for the ANTI-LOCK,TRACTION CONTROL SYSTEM and found a code 51 This is a code for problem with the engine control computer system - We checked engine control computer and found code 25 This is a code the air fuel control lean - Then we tested the OX1 O2 sensor and found it to be BAD. WE replaced the sensor and retest the system. IT figure out the problem.

[UCF3]

Let's let Amphora pull the diagnostic code, instead of guessing on what could be the solution. We've all had the Trac Light error on our cars; I still have mine on, but until I pulled the code, didn't know what it truely meant.

AutoZone rents for free <_<, interesting!

[91ls400]

I am thinking about going and getting to tool, is it a standard reader? Does my 91 even have a diagnostic port, and if so where the heck is it?

[UCF3]

Ones in the engine bay, to the right of the Lexus emblem "diagnosis" in this picture.

The other one is under the dash of the steering column-close to the kicker panel.

[amphora]

Hi everyone,

Firstly: thank you for the suggestions ! Really great to read your ideas on this problem.

I finally got the car to mechanic and asked him to change/flush the brake fluid...he did and so far...no unexpected TRAC light occurences. He did scan for codes and found a 45 for primary throttle position sensor (tps), 51 for engine control module (ecu)...but, my ck engine light never comes on and a 19 found on the right side of the ABS I believe he said...he has nothing for this code ! Does anyone know what this is for ? He did say IF the light came on I would have to go to Lexus for repairs. So, I am keeping my fingers crossed at this point but the brake fluid change, which he said should be done every 2-3 yrs, has been a good thing. Thanks again, will keep reading and writing.