[JoshS98]

Originally Posted by NZE90

Great work! If you go into the "service function" tab in ISTA you will find the DSC hydraulic unit adjustment service function which should take care of those codes.

Just got that done and have no codes! Besides AUC but who really cares about that and honestly I’m gonna clean it and follow the wire to confirm is not also rats.

And I guess my TPMS light but I just had to google how to get rid of that and I was too excited to do that before taking a photo.


Thank you all for all your help! Helped make the dream of an e90 being my first car become a reality. Was very tempted to sell it at some points and be rid of the problems but everyone here helped keep me willing to continue.

The advice and experience and knowledge all of you have is incredible.

Anyone who comes across this diagnosing problems, don’t give up.

And when you find the tiniest piece of rat poop on your engine cover you should really give it a closer look.

[Nevin57]

So is there any way that a failed dsc can cause the wipers not to work via the switch? After going through this post I've been testing my dsc and it all seems to check out but I'm not sure if my new to me szl not being coded is the issue or if it's still from before I managed to break mine.

[ptpending]

yes, the szl is connected to common car can bus via dsc in e9x
while wiper relay is connected to jbe and communicated via can bus as well

[houtan]

Thanks for all of the information in this thread and seeing it all the way through. I am dealing with a similar issue where the troubleshooting process will be similar so this is going to be immensely helpful.

Quick question, when you were troubleshooting the pt can signals to the DSC connector for example, do you do that with the connector removed or while it’s still connected to the DSC?

Also, any tips or things you’ve learned on what you had to get for your volt meter to do the testing at various connections would be immensely helpful.

I have started my own thread on 1addicts as well.

[JoshS98]

Originally Posted by houtan

Thanks for all of the information in this thread and seeing it all the way through. I am dealing with a similar issue where the troubleshooting process will be similar so this is going to be immensely helpful.

Quick question, when you were troubleshooting the pt can signals to the DSC connector for example, do you do that with the connector removed or while it’s still connected to the DSC?

Also, any tips or things you’ve learned on what you had to get for your volt meter to do the testing at various connections would be immensely helpful.

I have started my own thread on 1addicts as well.

Gonna read through your thread after replying here. Forgive me if I forget specific names of parts and stuff.

Anyways I tested it both attached and detached depending on what I was trying to eliminate as an issue at the current moment.

Knowing the PT-Can bus should be 60ohms let me really narrow down where the wiring break was.

I could read resistance from the EKMS up to module under the passenger dash. JBE I think? I could also see resistance from the DSC into that white sealed wiring box under the hood.

Unplugging the EKMS removed the resistance from it at the JBE so I could confirm there was no breaks up to that point. Seeing no resistance there while I should have seen the DSC resistance since it was still attached let me know the break was somweheee between the DSC and the JBE.

Then starting to check for the DSC resistance at each connector allowed me to see what points it was being lost between


Hope that all makes sense, takes time but probing for resistance at each connector in the loop while unplugging the DSC/EKMS was really the easiest and only way I found.


Definitely get needle probes for the multimeter or do what I did and get thin wire to “extend” your thick probes.

Even if they just fit shoving the standard ones into connectors and such can just cause more issues.

[edknights]

What an amazing thread! Massive thanks to JoshS98 for documenting his experience and everyone who contributed. Its just helped me trace the cause of a non-communicating DSC… turns out the DSC is fine, I’ve found a solution, but even speaking as a proffesional electronics guy I have no idea how this has worked…

Last week I got a red brake fault light on the dash. Plugged ISTA in and had both DSC and PDC (parking distance control) modules not responing, faults both recorded at the exact same mileage. I faffed about with the DSC for a bit at first as this was far more concering both for safety and also my wallet… traced the loom, verified voltages/continuity, put an oscilloscope on both CAN bus’s to the DSC etc (thanks again to the excellent info in this post) all looked ok.

It wasn’t till early today that I thought I’d have a look at the PDC. Unplugged it, and immediately the DSC came back to life… albeit with 1 million codes now logged across both DSC and multiple other modules. I reconnected the PDC, guess what, DSC dissapeared again…

Pulled the PDC again, reset codes, drove around a bit, all OK - just need to remember to not reverse into a wall without the beep beep beep from the PDC…

I immediately put it down as ‘the PDC must have been shorting the CAN bus, or locking it up with bullsh*t messages or something, preventing DSC from communicating’. Its just occured to me the PDC is on the K CAN and DSC is on the PT CAN…

Anyone whos knows a bit more about CAN bus than me know if the PT and K bus’s are both transmitted over the same pair of wires, or actually physcally/electrically seperate? Or could the PDC possibly be causing a problem on the K bus that is getting through the JBE onto the PT bus..?

I’ll have a good look through ISTA wiring diagrams when I get a chance… wonder if the knackered PDC module is a syptom of loom damage or something that I need to investigate further.

1st photo - first scan, DSC and PDC not communicating
2nd photo - 2nd scan, PDC unplugged. Loads of codes everywhere!
3rd photo - codes reset after test drive, DDE fault is pre-existing code for knackered glowplug

Again, appreciate the concise, informative effort made here!