Transmission fail safe..

[Themoog]

Right.
Tonight I’ve taken every fuse out to check and they are all ok.
Headlight removed to get to the ABS unit so I could unplug the cable, check and refit. I took out the ecu from the base of the windscreen, unplugged everything and refitted. The 30a fuses were also checked. The only one I haven’t done is the transmission module behind the glovebox which I will tomorrow.
As far as I could see everything looks clean and dry - brand new looking.
I’ve stuck the ctek on it until tomorrow when I’ll rescan it and run it again.
Anyone got any other ideas…

[X5chemist]

Today, this CAN video popped up on my play list
Interesting info on how DME, ABS, and trans module communicate. Time for a DVM and oscilloscope.

[Themoog]

Looks interesting. I’ll watch it later.
Mine is definitely something breaking down when the car warms up. Three times now I’ve ran it from cold for circa 30 min then it all goes wrong..

[andrewwynn]

I would try unplugging the abs module and see if you can drive without getting failsafe. The time delay is symptom of how intermittent abs module will trip the trifecta. I'm guessing a can buss may be connected to the abs module and is getting shorted when heat gets into the abs module.

Not sure if the speedo will work when it's unplugged and I wouldn't drive more than 100km with it unplugged might get a tamper dot.

[Themoog]

I wasn't sure if I could drive with the abs module unplugged. It did cross my mind.
It's uncanny that the above video has exactly the same symptoms as mine and I did have the abs module pack up on my old E39 years ago although that had the trifecta lights on whereas mine doesn't.

[Themoog]

Latest. Had an auto electrician out today. The only module that wouldn’t communicate was the abs module according to him so that could be the culprit.
I’ll have to remove it and get it sent off for test poss repair.

[X5chemist]

Out of curiosity, did he check network communication to the ABS module?

[Themoog]

You know what - I actually thought I was wasting his time. I’ve used him before and he seemed ok but this time I had a negative feeling if you know what I mean.
I left him to it but he was only here 40 mins and he was fannying around with the ignition switch and whatever but I did see that his diagnostic did not communicate with the abs but it did with everything else. If I was the sparky I would have probed the abs module connections and done a thorough job to confirm but that’s just me. It only cost me £60 so it’s not the end of the world.
All the evidence points to the abs module and it’s off now and being collected tomorrow to be tested (£45) and if it’s faulty then it’s £200 to be repaired with a lifetime warranty.
Do they just say it’s faulty? Who knows.. Problem is that I don’t want to just keep chucking cash at it to find the fault - the wife is already questioning my logic. Her opinion is that if a car has a problem just sell it and buy a new one..

[wpoll]

Fix it = few hundred quid....

But a new one = rather more than a few hundred quid....

What was that comment about logic?

[X5chemist]

False data can take you down a rabbit hole. Interesting video on how "live data" can mislead you. A network check plus power/grounds checks can save time and money.