Complete dashboard failure - where's the fault?

[DANBROAD]

Hi guys, wonder if any of you have seen this before... had this problem intermittently for a week...

1. Upon starting the car, all is normal, all gauges work fine.

2. After about 2-5 minutes I'll get any number of warning lights. Initially it was 'brake failure, stop safely' but this weekend it's been 'SRS Airbag urgent'. The warning lights on the dashboard light up [usually the ABS and the ([P]) lights but it could be any of them].

3. If I happen to be indicating at this point, the indicator 'click' disappears and the indicator arrow lights 'stick' on. The indicators still work on the exterior of the car.

4. Finally, all the gauges turn off, along with all the lights except the ABS and ([P]) warnings. The illuminated yellow central hazard flashes occasionally.

5. All radio controls, climate control, door functions and steering wheel functions stop working but in various combinations of problems - not the same thing every time.

It's important to note two things - firstly, the windscreen wiper and indicator controls do exactly what they should, but with no interior feedback. Secondly, the car itself drives perfectly - mechanically, it is fine. I've tried the turbo, the power steering, the ABS - still works perfectly.

6. When I stop the car and turn off the ignition, even with the keys out I get the 'no seat belt' audible alarm; again, intermittently. Even happens when the car keys have been out for some time.

7. When I come to restart the car, one of three things happen: Either, the fault persists and no gauges or interior dash warning lights work; or the car just won't turn over - nothing, not even the starter; or finally, it'll just turn on perfectly as though nothing has happened and be fine again.

Today the car's finally been doing it more than not; I know this is an electrical problem. Intermittent fault suggests no one 'blown component' or permanent failure of a part. I figure either a bad earth or a loose connection - but where? Is the ignition reel a likely culprit, or could this be a Databus or CEM failure?

2005 S40 UK, 128,000 miles, owned by me from new. No recent electrical work [CD changer replace under warranty at 60k] otherwise FSH and cared for.

It's going to be a dealer fault-code job, but I'd expect it to throw up a hundred fault codes. Is this a known issue? A forum search found nothing exactly similar, at least nothing I could find...

Any advice gratefully received...

[4 forty]

do a search for "wiring loom" underneath the radiator.

[DANBROAD]

4 Forty, thanks for the reply! I was aware of the wiring loom problem on the older model S40, but not that it continues on the new model.

Anyway, this morning all was perfectly fine again - until lunchtime, when my trusty steed came home on the back of an AA lorry.... wouldn't even start. Just the engine management light, the headlights and the windscreen wipers on full blast when I turned the key...

Interrogated the DTCS lastnight - basically lit up like a christmas tree. ECM and DIMM just about the only things not posting error codes. No sparking or loose earths, and no battery woes.

Anyway, it's now outside an auto electrician's ready to be VADIS'd and sorted. Once I know what it was, I'll post here to let you know.. might help future googlers...

[Clan]

there are network problems there , has the pollen filter been changed recently? look closely at each multi plug on the CEM under the glove box , sometimes they can be kicked loose by a passengers foot , have you lost the protective felt cover ?

[DANBROAD]

Thanks for the helpful replies - Clan, looks like you're right on the money. The auto electricians couldn't find any fault, so I ended up at the dealership for the day yesterday.

They VADIS'd the system, and found plenty of logged error codes, but no one code that was active - again, couldn't find the fault.

However, they removed the CEM and inspected it - no abnormality seen - and refitted the CEM unit. And the fault hasn't happened since, which given its previous regularity suggests it's been sorted out. Two days on, there are no logged errors in the system.

So, on balance it looks like a poor CEM unit connection, even though the protective cover was in place and I rarely have a passenger in the car. Removing and refitting the CEM sorted the problem out. Hope this helped!

[acl]

hope you can help but can the CEM be removed at home or is it a dealership piece?

my wife has just recently cleaned the car VERY THOROUGHLY and my xc90 went through a complete electrics failure, even though engine fires fine. It has redressed itself, when the AA turned up, although the key is now not recognised by the car.

fyi

my symptons are exactly the same as 1st post, on a 2004 se now at 82k

[s40_kid]

Originally Posted by acl

hope you can help but can the CEM be removed at home or is it a dealership piece?

my wife has just recently cleaned the car VERY THOROUGHLY and my xc90 went through a complete electrics failure, even though engine fires fine. It has redressed itself, when the AA turned up, although the key is now not recognised by the car.

fyi

my symptons are exactly the same as 1st post, on a 2004 se now at 82k

This can be removed at home. I rmeoved and re-seated mine after experiencing similar problems in this post

[T4FLY]

Checking the connections beneath the glove box fixed it for me (2005 S40) Got to the stage that the indicators stopped working, windows wouldn't go up etc not to mention all of the other warnings.