VSC AGAIN and AGAIN and now some codes – anyone ever figured this out?

[Jock666]

Hi again folks. Well after 8 years I’ve gone and bought a decent scanner/code reader – Autel DS708 and plugged into our 2003 GS300. For 95% of the time we have owned this the VSC/ABS lights have been on – thought we sorted it out 3 times 1) brake fluid reservoir was 5mm low 2) the bank 2 sensor 2 oxy heater/sensor was changed 3) reset the Yaw rate sensor (even made an OBD plug up specially to make this easier as the generic code readers have been known to trigger these lights on Toyotas for some reason – they all worked for a little bit then back again. The lights normally illuminate after 1-2 mts of car movement.

Now we also have the TIS Dealer software (disappointingly very basic old thing though) and both systems show NO OBD or fault codes anywhere. The abs sensors all read fine during driving.

Having gone deeper into the new scanners system I go to the ABS section where the Yaw sensor can be reset and the utility allowed another fault scan and the pictures below show an alarming amount of faults!!! Physically impossible for them to be real – it also allows you to clear faults at this menu but….it does not clear them – they remain in the system! Is it possible that’s where the real culprit is living????

Now before you ask – every mechanical an electrical component on this car HAS been changed from the complete drivetrain (engine/box/diff/exhaust) to everything under the hood – all except the ECU – and despite the mind boggling cost – the exact same problem exists – by simple conclusion (bearing in mind the donor car drove with ZERO faults) is that the fault remains in the ECU - ????

Now after years of probably reading every post on the subject surely someone must have got the bottom of this cr*p system that even turns off the VSC when the cat heater senor goes faulty??? WHY??? – it’s not part of the traction/braking circuit?

Is there maybe a bypass for this??

Help….because if these do not sort the problem I am going to have to scrap this amazing motor – sometimes you have to know when to let go…..

[steve2006]

From how I read your post you have replaced everything except the ECU, so why not the ECU if you have a donor car available with the same ECU?

[Jock666]

Simples....after drivetrain was changed my son sold the lockset and ecu whilst I was working abroad. Regardless, at no point in any conversation or on forums have I ever come across anything (I am in the Trade) even remotely blaming problems on this particular Toyota/Lexus fault with the ecu and still believe that to be so.

Seems this is one of those enigmas that Toyota have had for 25 years in their vehicles and never bothered to sort....but someone out there must have!

[steve2006]

It is well known that there have been problems with Toyota engine ECUs fitted to the LS400 range due to the failure and subsequent leakage of electrolyte from capacitors on the printed circuit boards causing track damage and various faults to occur.

If it is assumed that the same types of components are used in later models could this not be a potential cause of the problems you are having taking into account the amount of spurious fault codes present as these components are fitted mainly to remove any unwanted electrical spikes and surges from the car's electrical system. If these are no longer effective in doing this job the ECU may be receiving inputs that may be confusing the processors and codes are then flagged up. Maybe the exact cause has never been discovered as no one has ever looked inside the ECU to check for this type of damage.

I recently visited a vehicle ECU repair centre and I certainly remember Toyota ECUs being there on the shelves awaiting repair.

[Jock666]

Hi. ECU's were common failure on MK 1's due to capasiter leakage - does not really seem to have carried over into mk 2's though - except for the Levinson amps!

All the C codes are body related - what confuses me most is why these cannot be cleared!

[Mihanicos]

Normally, faults that bear no relation to each other, for a specific code, point to bad ground connections. Trouble codes that are cleared and return immediately are permanent indicating short or open circuits relevant to the code in question.

At this instance, I would make certain that all ground connectons have an almost zero resistance to the 12v Battery negative terminal. A ground connection wire is connected to all the car's Ecu and you must find it and check itq.

A 5v reference voltage is established at the car's circuit which is used for signal purposes and data collection from the various sensors. Each Ecu sends and receives 5v pulses for various purposes.

Make sure this reference voltage is available and stabilised.

Refer to the circuit diagrams of the car to identify the ground, 5v reference voltage and all relevant sensors qwiring connections pertaining to the codes in question.

Sometimes by pulling out the multipin connectors to the various Ecu and reconnecting them will improve contact resistance.

Good luck!