I have started a new search this week with again the strangest outcomes. I was pleased that M3W Service France had an ECU and a TSM in stock, which they sent to me and allowed me to see what would happen when I swapped them.
I first did a test ride with the different ECU. The changing of the ECU didn’t make any difference in behaviour regarding idling. So now I’ve tried three different ECU, ’s there was not any difference.
I did a second test ride WITHOUT any TSM at all. The car start and runs normally (except for idling). But no turn signals and no high beam light. The dipped beam was working. Instruments like Speedo are working normally. Switching on hazard lights without keys runs the fuel pump, and you can start the car without keys. High idling was still there, even without any TSM.
Changing to the different TSM gave strange results during my third test ride. Depending on which kind of light you are turning on, it blows fuses from 7-9 or 10. Intermittent high idling was still the case and happened as much as before with the “original” TSM. As well as the starting of the fuel pump when you turn the hazard lights on.
This above behaviour was also the case when I used the TSM from my other car.
That means two “good” TSMs working normally in other cars give strange behaviour in this car.
As these other components don’t make it any better, I put back in the TSM and ECU, which belong to this car.
The “original” TSM let all things work normally. The lights on don’t blow any fuses, and all working normally. Hazards light turning on let's run the fuel pump with all three TSMs
I disconnected one by one the instrument connectors C31 and C32. Now the fuel pump didn’t start any more when turning on the hazard light. The hazard light was blinking normally. The lights were normal or not working, depending on which connector was disconnected.
I connected the “original” TSM and ECU again and went for a fourth test ride. This showed that high idling was still intermittent, but the rest worked normally.
To ensure that disconnecting the VSS would solve the problems with the high idling, I went out for a last test ride. Hurrah, hurrah, high idling is completely gone. Only no speed indication, and the turn signals don’t switch off automatically. The odometer also doesn’t work. But who cares? At least the engine now behave normally again.
As Richard suggested, the only next step will be cutting the yellow /white cable at the loom bomb. But I wanted to keep it for the last as cutting is very easy, but repairing a cable in such an ugly place is a nightmare.
I've checked the voltage at the VSS connector near the wheel. The R/Y shows 4.99 volts, and the W/Y shows 4.88 volts. This is the same as on my other car.
So much work and headaches are still there with all the above knowledge.
