This winter, I did on both our M3W's necessary Centa upgrades.
For one of the cars with the idling problems, I did a thorough visual check on the engine cable loom and the chassis cable loom.
I couldn't find any discrepancies.
Last week was finely good weather to do a first test ride. Centa worked fine now, and all the rattling noise inside the Centa was gone. But the intermitted fast idling was still there.
Most of the time, it runs well in idle, but without any reason, it remains at 2500 rpm when coasting and drops to normal at a standstill. The engine light remains off during this. Sometimes at a standstill, the engine light comes briefly on, and the idle goes up to 2500.
So still the same annoying problem (see my explanation in previous posts on Talk Morgan; Revs not going to idle).
During this test ride, we discovered that the main lights didn't work; only the parking lights turned on. The green light indicator in the speedo was illuminated.
I started a new search.
I found out that fuses 7,9, and 10 were blown. So I replaced those.
All lights worked normally again. With the exemption that the high beam only works when pulling the stalk switch at the steering wheel towards you (signal mode) and does not work when pushing away from you.
And now the problem even got worse and a second problem arose.
When the contact key is OFF and I turn on the switch from the alarm lights the fuel pump starts running and the oil pressure light comes on!
But the alarm lights don't work.
When I switch ON the contact key without starting the engine, the fuel pump comes on like normal, and when I switch on the alarm lights, they blink normally.
I disconnected the chassis loom from the engine loom. I turned the contact key on and off, and on both occasions, the alarm lights worked normally, with and without the contact key turned. Now the alarm switch didn't start the fuel pump running.
I connected both looms again and disconnected the ECU. The alarm lights worked normally again, with and without the contact key turned. The fuel pump didn't start running when I switched on the alarm lights.
I swapped the TSM module (C16 turn signal module and head light unit) with the one from our other car and it even got crazier.
With that TSM module from the other car, switching on the main lights directly trip the 20 Amp fuse number 7 fuse number 9 and fuse number 10.
But that tripping of the fuses doesn't happen with the original TSM. It happens ONLY with the TSM from the other car.
With this other TSM installed and leaving fuse 9 out, the fuel pump doesn't start running when I turn on the alarm switch but turns on the oil pressure light. This is with the contact key in OFF.
When I disconnect the TSM unit from the system and turn on the alarm switch, the fuel pump starts, and the oil pressure light comes on. This is with the contact key in OFF.
I swapped the ECU with the other car, but all this mystery behaviour remained the same.
So it probably doesn't have anything to do with the ECU.
I tried swapping the ECUs last autumn as well when searching for the high idling, without any results.
I disconnected the two connections at the speedometer, as Planenut gave me that suggestion last year, but that also didn't change anything.
I've already swapped all diode relays, but that doesn't make any difference.
What this all has to do with the intermitted high idling, I don’t know, but for sure, there is something wrong. But what?
Can you imagine I’m getting desperate? Who can help me?
Last edited by Laurens; 11/04/23 08:12 PM.
