Volvo V50 D 2011 issues

[sanja4g]

Hello
We recently purchased a V50 D 1.6 2011 model and are now facing some electrical issues.
1 Key fob not working and doors not opening or locking ( battery changed).
2 Windows not working
3 Airbag warning light comes on upon start up and eventually after a few miles mostly goes out.
4 Engine service light keeps coming on
Car drives ok and not in limp mode....Yet.
Any suggestions or ideas on how to fix this?

[Moose Test]

A suggestion, based on the number of disparate electrical systems that are affected, is that there is an issue with the CEM.

A friend of mine has a V50 and they started having similar problems with locking and windows, progressing ultimately on to engine warning lights, limp-mode and finally a failure to start.

In their case, I removed the CEM and cleaned all connector contacts, fuses and fuseways, and the PCBs themselves. This resolved all the problems they were experiencing. There was mild but visible surface corrosion on some PCB tracks.

I was minded to do so, having google-searched the symptoms. Whilst it would be without real evidence for me to claim that the V50 has this as a 'known issue', it does seem to happen to some folks and I for one have seen it first hand.

[Sotosound]

What is the CEM?

[Moose Test]

CEM = "Central Electronics Module"

It's a microprocessor based control unit that runs a lot of the car's software applications and communications buses. As the name might suggest, it is central to the operation of all electrical systems. Specific, usually high speed, mission critical functions are handled by separate modules (e.g. the ECM or "engine control module") but they are also highly dependent on the CEM during normal operation.

On the V50, as with many (if not all) Volvos, the CEM also functions as a fusebox for many of the car's circuits, and is located in the passenger footwell area

[Simmy]

a quick scan with diagnostics would point to where the qlitch in connection is

[Moose Test]

https://www.volvoforums.org.uk/showthread.php?t=302607
https://www.volvoforums.org.uk/showthread.php?t=333978
https://volvoforums.com/forum/volvo-...uestion-94466/
https://www.swedespeed.com/threads/a...ck-cem.639732/

https://www.youtube.com/watch?v=ATPpt9gCXvo

Clean, or have cleaned, the CEM connections first before spending any money on garage diagnostics. You can go there once you've eliminated a potentially common but simple problem.

Usually I'd be the first to advocate for a DSTC code read but the failures are in so many systems it really does point to a central systematic failure. And, there's quite a bit of anecdotal evidence to support it.

[Simmy]

diagnostics is always the way to go especially for folk with little or no knowledge of cars can go they can go straight to the problem to avoid spending out on un needed parts.

[Kev0607]

Originally Posted by Simmy

diagnostics is always the way to go especially for folk with little or no knowledge of cars can go they can go straight to the problem to avoid spending out on un needed parts.

Agreed. Get it diagnosed properly by a garage.

[sanja4g]

Have ordered some electrical switch cleaner and will have a go next week at cleaning it. The location seems slightly different to the ones in all the you tube videos. On my one it appears to be on the passenger side, under the footwell, but not on the front wall but more on the ceiling of the footwell. If that makes sense, upside down. Anyway will have a go. I don't have any diagnostic instruments apart from a multimeter, which in this case , I guess, is pretty useless.
My biggest worry is getting the thing back in as will be working upside down.
Thank you everybody for all the help and suggestions.

Originally Posted by Moose Test

https://www.volvoforums.org.uk/showthread.php?t=302607
https://www.volvoforums.org.uk/showthread.php?t=333978
https://volvoforums.com/forum/volvo-...uestion-94466/
https://www.swedespeed.com/threads/a...ck-cem.639732/

https://www.youtube.com/watch?v=ATPpt9gCXvo

Clean, or have cleaned, the CEM connections first before spending any money on garage diagnostics. You can go there once you've eliminated a potentially common but simple problem.

Usually I'd be the first to advocate for a DSTC code read but the failures are in so many systems it really does point to a central systematic failure. And, there's quite a bit of anecdotal evidence to support it.

[Moose Test]

Personally, I think it's worth a try if you're prepared to invest a couple of hours of your time and you have the confidence to take it on.

If you don't already have the DICE and VIDA tools then you'd need to acquire them or book into a garage having them. Either way, you're looking at £100 upwards and even then, if it shows comms/signal loss errors to multiple modules the place to start is still going to be cleaning and checking wiring connections.

Since we're talking basic maintenance rather than throwing new parts at it, I don't see the issue with making an informed guess, if you're prepared to spend the time and a few quid on consumables (and still be defeated).

There's still every chance the CEM has failed and is irreparable but cross that bridge when you get there.

I recommend a contact cleaner from a well-known brand and also a small plastic brush to be able to give the contact surfaces a good scrub over. In the case of the vehicle I repaired, I went the whole hog - I removed all the fuses (noting carefully where everything goes come replacement time) and opened up the module, so that I could scrub and clean the tracks and solder joints of the PCBs too (mineral deposits from traces of corrosion can cause problems too, not just the contacts in the plugs).

The location in the vehicle sounds the same as the one I worked on. It can be done but you'll need to contort yourself in the footwell a bit to get good access. A head torch for illumination will make things easier.

AND - take some pictures of where all the plugs go into the module before you starting taking them out. They are all keyed and of different sizes (from what I remember) so they can't go back wrong however, there are quite a few and it can be daunting when faced with them all hanging there ;-)

Good luck.