S80: Electrical 2009 Volvo S80 DTC U0231 and B1131

[Goc5]

Hi. My 2009 Volvo s80 has the two error codes listed in the title.

This has lead to me not having operational wipers. Initially they wouldn't turn off, and would also activate randomly, ignoring any input from me.

This eventually lead to them staying active when I had the key removed from the car, so I had to remove the fuse itself to get them to stop.

Since that they haven't worked at all, and I can't clear those two codes. I've tried replacing the wiper motor, wiper stalk, checked all fuses, checked the connectors on the ECU to see if there's any corrosion, etc. All of this has lead to nothing, I'm out of ideas.

The code u0231 says: data bus, rain sensor control module - no communication.

The code B1131 says: Wiper Motor Module. Bus Signal/Message Failures. Missing Message

I've searched this forum and others and seen other people suffer from this issue, but I haven't found one concrete solution that works, people either stop replying to the topic or fix it with something like a motor replacement, which doesn't work for me.

Any help is greatly appreciated as I live in a country that has rain 99% the time

[GrahamBrown1]

From the code description it would suggest a wiring fault. Rain sensor could be missing from the network. It is connect via can lines and power and ground I would expect. The wiper motor works via lin bus which is the bus missing message. You really need a wiring diagram and some electrical test equipment to sort this yourself. The use of a scope would allow you to see what’s going on but at some point it is going to involve manually tracing the wiring I would expect.

I can’t be anymore help than that because without the above it is purely guess work.

[Goc5]

Ok, just in case anyone else ever comes across this with a similar issue I'd like to post my resolution to it.

I removed the alarm module.

That solved all my issues, wipers work, rain sensor works, no error codes, no warning message about my alarm not being connected any longer, nothing.

From opening the alarm it seems that the battery was going bad and must have effected the alarm's PCB as I found a short in it, which then caused it to send some messed up signals to the CEM and confused it in regards to what's happening with the rain sensor and the wiper motor. That's all I can assume from what I'm seeing, but outside of that I have absolutely no idea why it would cause so many problems.

So, if anyone else ever suffers from these error codes or has these issues then my recommendation is to check the alarm module first and see how you get on from there.

On my model Volvo S80 2009 the alarm module was on the passenger side inside the engine compartment, underneath the wiper cover, right beside where the CEM is located. So, you have to remove the wipers, then remove the cover, then locate the CEM, then on the right of that (depending on which hand drive your car is) you'll see a black box secured with two 10mm nuts.

I disconnected my battery, removed the alarm, plugged it out, reconnected battery, started car, all problems solved.

Hope this can help someone else in the future

[GrahamBrown1]

What lead you to suspect the alarm module was causing the faults? Not heard of one do this before normally you just get the random alarm going off and alarm related messages ect. Good it was as simple as the unit failing and an easy fix.