Electrics: Is the CEM on my XC90 dying/dead?

[Parknest]

I think I'm having this problem with my XC90.

After driving for a certain length of time (more than 2 hours, I think). I would hear a thump from the transmission, what sounds like some relays clicking, a loss of power to the radio/CD, indicators, wipers and the instrument panel. The climate control would still be working, the headlights would still be working and it would drive fine but if I stopped and tried to set off again it would respond very slowly as if it was trying to set off in a higher gear. Before losing the instrument panel, I would get "Brake failure Stop safely" and SRS messages on the display. This has been going on sporadically during the time I've had my XC90. It happened yesterday after a run out to Burnley and Oldham. I was able to get home and I scanned it with my scantool and these are the fault codes that came up.

Diesel Engine
ECM-A03B Communications, Central Electronic Module. Faulty Signal
ECM-A500 Control Area Network (CAN) Fault. Faulty Signal
ECM-9210 Cruise Control. Faulty Signal

SRS
SRS-00D5 SRS Indicator Lamp. Signal Missing

REM
REM-9F21 Cargo Compartment Lighting. Faulty Signal.

CCM
CCM-0021 AirQuality Sensor. Internal Fault.

ABS
ABS-0094 Communication Between Control modules. Communication Problems With Active On Demand Coupling.

CEM
CEM-1A64 Communication With AOC Control Module Signal Missing.
CEM-1D07 Control Module Internal Fault.

CCM-0021, ABS-0094 & CEM-1A64 were already there and the last 2 relate to a faulty DEM so they can be eliminated for now.

2 of those fault codes ECM-A03B & CEM-1D07 seem to point to a faulty CEM.

I came out to it today when it was stone cold and it has got worse. The remote wasn't working even with a new battery. I unlocked it with the key, turned the ignition and within a few seconds I would get the same power loss as before but I could start the engine and it would struggle to set off. I'm now unable to scan for any fault codes. I'm now suspecting the CEM has finally given up the ghost.

Can anyone shed any light on this?

[Parknest]

I've just spoken to a local specialist (Volvo Specialist Car Sales in Brighouse) and they're going to collect it tomorrow. They seem to think it is the CEM but they need the vehicle in front of them. Something they mentioned was that water ingress at the top of the CEM could be the cause of the problem. I could easily check this but I don't want to complicate things by digging in before they collect it.

I'll keep you posted.

[Clan]

Originally Posted by Parknest

I've just spoken to a local specialist (Volvo Specialist Car Sales in Brighouse) and they're going to collect it tomorrow. They seem to think it is the CEM but they need the vehicle in front of them. Something they mentioned was that water ingress at the top of the CEM could be the cause of the problem. I could easily check this but I don't want to complicate things by digging in before they collect it.

I'll keep you posted.

It is probably a cracked solder joint in the CEM , You wont get water leak problems on a 2003 ! That started after they redesigned the top sealing for the 2005 models.

[Parknest]

I only have basic soldering skills so such a repair is probably beyond me. I'm gonna have to bite the bullet on this one and get it repaired professionally. The specialist offers a repair service for modules so I might get them to do the differential module as well but that's another story. I can also confirm that the hazards are not working so that pretty much confirms that the CEM has finally died.

[john langrick]

Take reassurance that there are many places that can rework these items and give lifetime guarantees.

However, I did have similar symptoms on my xc90 a few years ago, mine is my03.

Mine turned out to be simply the ground cable to the battery had a bad connection.

If only these things could be that simple.

John l

[Parknest]

I wish it was something so simple. I can't even get to the battery (rear tailgate doesn't even open with this loss of power to almost everything).

My XC90 has been collected today and they're gonna have a look at it tomorrow. I'll keep this thread updated as soon as I hear something.

[Parknest]

I've just spoken to the specialist and they've confirmed that there is NO signs of water ingress confirming what Clan has posted. The CEM is the prime suspect and will need further testing. He also suspected the DIM and DEM modules too.

[Clan]

Originally Posted by Parknest

I've just spoken to the specialist and they've confirmed that there is NO signs of water ingress confirming what Clan has posted. The CEM is the prime suspect and will need further testing. He also suspected the DIM and DEM modules too.

The CEM heats up and cools down in the car so subject to temperatures from about -10C to +50C in our climate which cases the soldered joints to expand and contact and eventually crack , they probably just need a dab of fresh solder , you may be able to see cracks around them with the naked eye or Magnifying glass.

[john langrick]

My re ommendarion for repair would be Volvo diagnostics but they are in east London.

They sorted my icm and gave a lifetime warranty.

You should be able to post the unit and if you want call lucasz.

My issue was indeed solder joints as the icm is very subject to heat variations.

Good luck

[Parknest]

I'd use Lucasz if he wasn't so far away. In fact I spoke to him about my "Anti skid service required" message and was able to confirm from the error codes (CEM-1A64 & ABS-0094) that the DEM was indeed faulty. I mentioned dry solder joints to the specialist when I spoke to him today. After that call I e-mailed them a copy of the report from my scantool which is also attached to this thread.