V50 Electrics : Weird electrical faults

[V50RLH]

Evening everyone,

I'm sure this fault has popped up before, so I thought I'd ask the experts.

I have a 2005 '55 V50 1.8SE. It's always had the odd electrical gremlin, but just lately, it's getting worse.

I can be driving along (no pattern as to time, distance, temperature), and then I start getting messages on the dash.

1. SRS Airbag Service Urgent
2. Brake Failure - Stop Safely
3. Reduced Engine Performance

This usually goes alongside the dials on the dash failing completely for a period of time (could be a few seconds, could be far longer to the point that even after the journey is done), and is also accompanied with various warning lights.

Sometimes the whole dash just shuts off after one of these incidents, and sometimes it just comes back to life. Pulling over and switching the car off sometimes sorts, but sometimes it doesn't.

None of the messages seem to affect the performance of the car, as it just goes on it's merry way.

I've even jiggled some of the connectors in the passenger footwell and that has been known to cure the fault.

It does appear to be completely random as to when it happens.

Have any of you other Volvo folks experienced the same problem? If so, do you know what might be causing it?

Your knowledge as always is greatly appreciated.

Russ

[dcw]

You are on the right track with the CEM in the passenger foot-well. Don't just "jiggle some of the connectors". Disconnect the battery, disconnect all the connectors and completely remove the CEM (it has plugs both top and bottom).

Check that the CEM is dry (especially if you have a sunroof with the notorious blocking drains that are well covered on here). Check that all the connections are completely clean.

Then put it back reconnecting everything as you go, making sure all the connections are good and straight and firm.

Reconnect battery.

Give it time...see if the problems are gone.

David

[V50RLH]

Thanks for that David,

I'll give that a try.

Russ

[Jjnt93]

Hi Russ,

I’m currently suffering with the same issue with my car.

Did you manage to get your car fixed?

Thanks,
Josh

[V50RLH]

Hi Josh,

For me, dcw's reply did the trick.

I disconnected the connector on the passenger doorand cleaned the connector. I then removed the CEM under the passenger glovebox and removed and cleaned each connector. Finally cleaning the connectors to the CEM and then connected it all back up.

That certainly dealt with it until I traded it in last September. If that doesn't cure it, a new CEM can be bought for around £50-£60.

Hope that points you in the right direction.

[Ian21401]

V50, D5, my 2007.
Owned by daughter until sold on to a neighbour when daughter bought XC70.
All the same symptoms, engine just died, brake failure warning, wipers on and key locked in ignition. It did this last December. RAC attended, cleared all fault codes and car was driven to owner's home. Then taken to local indi. Volvo specialist. All codes had already been cleared by RAC so they suggested blocked fuel filter which was replaced and car running again.
Car has done it frequently since. Recovered to same specialist who suggested alternator problem but no alternator fault found. Few weeks ago it did it again and was recovered to the indi. without attempting to clear any fault codes. Codes were read but all appeared to be the spurious irrelevant codes as reported in other threads so codes cleared. Indi. were advised of windscreen wipers operating when not switched on and previous left side sun roof drain blockages (above the passenger foot well) and agreed it was possibly a CEM or fuse box connection problem and agreed to do what they termed a "wiring check" They reported that no faults were found and car was returned to the owner. Owner has now lost confidence with the car as due to the nature of her employment she needs to have a thoroughly reliable car which is not going to fail whilst miles from anywhere. She is otherwise pleased with the car but seriously considering getting rid of it.
I have cleared the blocked left side sun roof drain twice whilst daughter owned the car and once since the present owner bought it so I volunteered to check out the CEM and fuse box connections as mentioned by others elsewhere in this forum but due to an injury to one of my legs I am unable to do so at present.

[Ian21401]

The V50 we had shut down again a few weeks ago. The current owner had a different mobile electronic fault finder guy come to her house check the car out. She reports that he stated that he found 77 stored fault codes and wondered why they were there if others who had previously investigated had reported all faults cleared. He cleared all of these codes and advised that he be called again if the engine shuts down again.

[Ian21401]

The lady who bought the car from my daughter loved it but it cut out again a couple of times. As she could not rely on it behaving as it should she has traded it in against a newer Skoda.

[mkusan]

My wife had similar issues this week, completely dead dashboard on powering up. It would spring back to life eventually until one of the doors would open or if interior light would turn on, then black out again. I disconnected the CEM and cleaned it thoroughly but the culprit was F46 5A fuse which showed no continuity on DMM. I presume that when the dashboard did work could be explained by arcing on its contacts.

Br

Marko