Well if it's a genuine M3, it makes you wonder why the loom has been joined up like that
Had it have been a conversion, I could have maybe understood.
Keep us updated with the progress.
I'll have a look at the higher res photo when I get home tonight too.
Parking sensors and mirrors are on the same fuse. If its blowing try disconnecting the mirror swich in the drivers door. Rollover protection light should stay on too if the fuse has gone.
Well I've had a chance to check continuity on the car today and it appears that the diagnostic port is connected ok to the engine ECU, but there are issues between the fuse box area of the engine bay and the cabling in the dash. It appears at least one wire is resistive or O/C between pin 1 on the diag port. It makes it through to pin 47 on the engine ECU but is virtually O/C to the ABS ECU.
Pin 12 on the EWS II ECU is also not connected to pin 41 on the ABS ECU so it's definitely broken somewhere. I guess I need to find X20 connector, at least that might help me to trace the wires through, but it's not easy as there just isn't enough wire to pull through to allow access.
I've only checked a couple of wires so far but it's not a good start.
On the upside, pin 20 on the diag port actually makes it through to pin 28 of the ABS ECU, so that one is ok!
The X20, IIRC, is the big round connector next to the fuse box, it joins the engine loom to the interior loom
Hopefully back on it tomorrow for a couple of hours. I just hope I can remember how it all goes back together, there's wires and connectors hanging everywhere at the moment!
I have contemplated sourcing another loom, but I hate to be beaten, so this may take a while.
Are these prone to broken wires around the bulk head area?
It's not a fault i've heard of before....
And your like me, you'd rather fix something, than admit defeat and just replace it
Let us know what happens mate
Well now I'm totally confused. Having been checking through the wiring for pin 1 from the diagnostic plug I followed the diagram attached. This led me to believe that there was a break where the connection arrives at the ABS ECU. Getting a bit more light in the foot well tonight I find there isn't a black wire in the cable to the ABS ECU. So I then look at the circuit diagram for the M3 ABS system, also attached, to find that pin 41 is actually connected to ground. So either the diagrams are wrong or I'm looking in the wrong places. AAaaarrrrgggghhhh...
Really hacked off now as it's been perfect roof down weather today!
Quick update. I haven't got to the bottom of why the diag port doesn't work, but I went back to the old fashioned method of checking the ABS and found the front passenger side sensor has gone completely open circuit. Just to prove a point I cut the wire and soldered a resistor across the ends and the ABS light goes out after self checking. It will come on again as soon as I move but it tells me what I need to know.
So I've ordered a new sensor from good old Ebay. I think I'll stick the car back together for now and try my luck with the MOT once I've got the new sensor. If it goes through that will give me a year to get to the bottom of the other problem.
Well things have moved on a little since the last update, but nothing significant. After resolving the ABS issue I decided to bite the bullet and stick it in for an MOT which it duly failed, but only on three bushes at the back and very slightly out on the emissions. So my friendly local garage fitted the bushes for me as I couldn't be bothered having had a bit of a run on MOT's of late, and they also had a fiddle around and got it through the emissions as well. So it now has an MOT so can be used for the rest of the summer. I also picked up a replacement alarm for a few quid from Ebay so all is better in my BMW world for now. It will come off the road at the end of September and get parked up in the garage for the winter, so I can take some time to figure out what the hell is going on.
The down side is, the diagnostic port is still dead but I'm starting to wonder if it is actually one of the ECU's pulling it down.
On the upside, I lost the locking wheel nut tool so I took it to the local main dealer who went to all the trouble of testing to see which number it was and then gave me a replacement for nothing. Now that's what I call service as although it's peanuts money to them, I'd never stepped foot in a BMW garage before so it sets a good precedent!
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