Hi, I have LS400 1992 more than 500 000km on it. I read lot of forums, discussion and need some advice, not found any info to solve my problem.

Few monts ago ABS and TRAC light come on, after 3 months park in garage. Steps done and notes:

1) ABS and engine ecu error codes check - no code
2) when ABS code check (Tc+E1), ABS+TRC light swithc off, than two times blinks ABS light, than can be hear relay close to front bumper switch off, and ABS and TRAC light get on.
3) Tried wheel sensorts check mode, ABS light quick flashing (check mode activated) after shift to D or release parking brake fast ABS light start to light constantly. No codes after check.
4) Changed ABS ECU by same - no change, same issues
5) Relays under glove box close to ABS ECU switch on when ign go on and holt till ign is on
6) TRAC second trottle selfcheck active when ign on
7) ABS sensors in wheels checked by servis - no failure (I will recheck by myslef)
8) TRAC high pressure pump and relay not switch on, no pressure in accumulator, but can be caused by not working ABS?
9) brake pedal when is press and engine run is very slowly going down
10) checked grounds, cleaned it, no change
11) checked capactiros in engine ECU, looks ok (no leakage, dirts atc)

Any advice what to be check?
ABS actuator bad?
Or can be caused by bad capacitor in engine ECU (not changed yet but looks ok).

Thank you

 

Hello,

A video of the Diagnostics procedure would be helpful to trace the steps.

Which connector did you use to run the Diagnostics? There is a Rectangular one under the hood, and Round one under the dashboard, they are not always the same, and may yield different results depending on the use. Other thing to consider is wires you use to actually short the pins, bad contact will not get you a consistent result. Best way would be to source an old O2 sensor or something similar, and cut the terminals out of it to use for diagnostics, here is a thread on how to take the connector apart.

What you can try is disconnecting some of the sensors and then running the diagnostics again to see if this function even works at all, and if the faults may be somewhere else. If that won't help, try shorting Pins Te1 and E1 instead.

Depending on the delays between each flash, it may indicate a Fault Code 11 - Open in TRAC brake main relay circuit. This is a main relay for the Traction system, located separately from all the other ones somewhere behind the Driver's side headlight, at least in US-Spec LS400. Check that the Coil receives the signal from the ECU and Switch is powered, here you can find more information.

Do you mean the pedal is harder to press? Try disconnecting the Vacuum Line going to the Brake Booster, do not start the engine, then check if the feel of the pedal will change compared to when the line is connected and engine is started. If the feel doesn't change much, it may be a result of the membrane in the Brake Booster being punctured. Other thing to try is taking out the ABS and TRAC relays to make sure that neither of those systems affects the feel of the pedal, which may lead to a solution.

Hope this helps and best of luck!

 

Thank you Arsenii, let me check next weekend.