Is the CEM on my XC90 dying/dead?
 

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?

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.

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.

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

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.

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.

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

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.

I've spoken to the specialist today and he told me that the CEM has come back to life. He's going to speak to his tech guy either tomorrow or Friday (27th/28th October 2022 for those who are reading this in the future). He's loath to send it off for bench testing as it would probably pass such a test as my problem happens more than 2 hours into a long journey and they don't do tests of that length. He said that the CEM might have to be replaced. At least he knows that there has been a problem when he collected the vehicle.

he needs to heat it up with a hairdryer for a while and look for cracked soldered joints

I've just spoken to the specialist and he seems to think that my non-working DEM could be the cause of the dying CEM and he wanted to test it with the DEM unplugged to prove the theory. When I told him that the problem started after 2 & a half hours of driving he said that it was probably the CEM. As I'd like to have the AWD working in time for winter and the next caravan outing, the plan is for them to remove the DEM and then I'll arrange to have it repaired by Volvo Diagnostic. As soon as I mentioned Lukasz, my specialist knew who he was and had dealt within him a couple of times in the past without any problems. The specialist normally obtains secondhand modules and reprograms them but he says that used DEMs are hard to find (I managed to find a couple of used ones on eBay) so he said getting it repaired was the best option and he'd rather have me do the legwork myself which isn't a problem.

try revtronics in bradford they repair all car electronic units cem / dem / dim . ect

Simmy, I saw your post on my other thread and the response is there.

I'm going to get the DEM repaired by Lukasz at Volvo Diagnostic and I mentioned the CEM problem to him. He agreed that the faulty DEM could well be responsible for the CEM throwing a wobbly so the DEM is definitely going to get repaired/replaced.

it was worth an ask at revtronics they have done dim repairs while you wait. if lucaz cant fixit no one can good luck with your repair keep us posted:regular_smile:

The DEM has already been sent off to Lukasz. He advised me to send it by Royal Mail Special Delivery which is what I did. Once the DEM has been repaired/replaced I can take it back to the specialist (Volvo Specialist Car Sales in Brighouse, West Yorkshire). They told me that it has been driving fine with the DEM disconnected but that's not a guarantee that the problem is solved.

I ended up getting a reconditioned DEM as mine was beyond repair and I've taken it back to the specialist to be fitted.

Sorry for the belated update.

I got the XC90 back 8 days ago and it is working fine. I've not done any long journeys yet which will be the real test. For now, I've got a fully working AWD with the dreaded "anti-skid service required" message finally banished. If the problem comes up again, I'll be straight on to the specialist for further diagnosis on the CEM. If it needs repair, I'll be giving Lukasz my business again.

Just to add to this, I've only just pulled the dashcam footage (thank feck for 256GB SD cards) and the day that this happened (15th October 2022) I'd left home at 12.57 and the first sign of trouble happened at 15.42 (according to the timestamp) so I'd been on the road for 2 hours and 45 minutes. There was a thump from the transmission. About 8 minutes later there was another such thump and I started losing most of the electrics starting with the radio/CD player, what sounded like relays clicking from the general area of the CEM, the 2 messages on the display before the instrument cluster stopped working. The climate control and the headlights were working and I had limited used of the wipers. The engine was still running but the transmission appeared to be in limp mode. The fault codes at the beginning of this thread were the ones that came up when did a scan as soon as I got home.

I know this is long after the event but I'm hoping this information might be of use in determining if the CEM is actually at fault now that I've got a timescale of when this problem happened.

it sounds like your fault may be heat related was your journey on a hot day? i see clan also thinks it may be heat related iv seen on other fourms that some have fitted extra cooling for the cem with heatsinks and computer fans it would seem your problem is not unknown .search the mathews volvo site for info and xmodex for cem cooling:cool:

Yeah, I'm aware of these possibilities and the jury is still out. I've had both my local specialist and Lukasz say that the faulty DEM might be the cause. It survived a trip to Costco in Oldham in rush hour traffic which included queuing for diesel. I need to run it continuously for at least 2 hours and 45 minutes to see if the problem comes back so I can't say for definite if the problem is fixed or not.

costco oldham 5 min walk for me try the clive brook heritage club meet in huddersfield to get expert volvo info and advice for free they are held on saturday mornings. check the web site for meet details and dates:regular_smile:

Oh feck! The problem has come back to haunt me. I was 3 hours into a journey and the problems with the loss of most of the electrics reappeared. I was able to get home and I got the same error codes as before when I scanned it. I'm 95% convincned that the CEM is indeed faulty. I'll be speaking to the specialist in the morning and if he agrees, I'll be sending the CEM off to Lukasz for repair. The faulty DEM was a problem but it wasn't THE problem. I'm glad this has cropped up before the first outing for the caravan this year.

I'll keep you posted.

how old is your battery and have you checked the output of your alternator volvos are well known for failing electrics low battery can throw up all kinds of gremlins it must be worth checking. before wrestling out the cem for repair. ps iv just looked at your scan tool print out it dose not seem to show voltage readings if voltage checks out ok then proceed with the cem ..when you clear these codes do all the same ones return straight away or later after driveing a good distance>

It is the same problem as before with the same symptoms so I'm making the call on this one. It starts up on the button and the problem only happens after 3 hours of continuous driving. These are the fault codes I had when I scanned it last week:

ECM-A03B
ECM-A500
ECM-9210
ABS-0094
CEM-1D08
SRS-00D5

I was able to clear all thses codes and they will only come back when I start getting the symptoms. It is now with the specialist who will remove the CEM and I will send it off to Lucasz for repair.

good luck with the repair . i hope this will bring an end to your frustrating problem keep us posted with the results i am very interested in the outcome .

The CEM has been removed and I've sent it off to Lukasz for repair.

I got the repaired CEM back yesterday and dropped it off at the specialist for refitting. Once that's done my troubles should be over.

lets hope so iv followed this post for a long time let us know your out come.:regular_smile:

lets hope so iv followed this post for a long time let us know your out come. did lucaz give any indication of what he found within the cem? :regular_smile:

I've no idea what the problem was. It came back with a sticker on it. I get my XC90 back yesterday an it is fine. As previously, time will tell when I undertake a long journey of 3 hours or more...

good to hear that you are up and running after all your troubles . are you a member of any local groups ? yorkshire volvo or north west volvo owners uk there are plenty of good knowledgeable folk in these type of groups . both have meets to talk all things volvo :regular_smile:

I'm just on this forum. It has already survived another visit to Costco in Oldham. I've not scanned my XC90 since I got the CEM refitted.

its worth joining some other groups as there are folk who are mechanics.. vida dice owners. paint specialists ect its good to have knowledgeable friends/ within easy contact . there is also the heritage club at clive brook in huddersfield for volvos over 7yrs old .with monthly meets .

And a year later.... how are things running for you?
Thanks.