I have a 2004 XC70, which uses a similar ECM setup as the S60. My sweetheart and I were driving at night through a secluded part of Vancouver Island when the first failure hit. Only in our case, it was 35 degrees Fahrenheit.

After a loud, jarring bang, all the cabin lights illuminated, immediately followed by a "Left Rear Passenger Door Open" message on the MFD. After another few miles, the dash failed completely. Only a 30 minute cooldown allowed the vehicle to operate normally or indeed even start. A terrifying problem to be faced with in the middle of nowhere.

After much scouring the forums and some empirical experimentation, I determined that this is a problem with the CEM, mounted behind the dash above the drivers left kick panel. The cabin heater, venting through the foot pan air directors, enveloped the CEM in a stagnant bubble of superheated air that caused the hapless module--already blessed with notoriously bad airflow and excessive shielding--to overheat and fail.

Being an IT guy, I've repaired many computers with overheat problems, and the XC70's CEM is no different than any other overheating computer. After removing the CEM, I removed the top of the chromed processor shielding box and elected to leave it off of the CEM. Utilizing forceps and patience, I installed --the kind normally used to cool memory modules in high-end gaming rigs--on the processor and every glue chip I could get to. I trimmed the black perforated plastic off of the top using a to increase airflow even further. I then affixed a to the top with tie wraps, such that it constantly blasts circulated air across the planar and heatsinks, and supplied power to it by wiring it into directly into the accessory circuit.

I've been pounding on it for the last four days in a winter shakedown roadtrip, through brutal Pacific Northwest winter driving conditions in freezing rain and snow, blasting the heater into the footwell for hours at a time. My XC70 has performed flawlessly. The cooling fan on the CEM, despite its size and relatively rapid RPM, is only audible upon vehicle start and even then only barely.

Instead of paying $4,500 for a replacement CEM from Volvo, or $1,000 for an Xemodex refurbishment of my existing CEM, I solved this otherwise terrifying electrical gremlin with about three hours of elbow grease and less than fifteen bucks.

 

This information was INVALUABLE for me....my 2004 S80 was doing the EXACT SAME THING. I thought it was the ABS module, but temporary removal didn't help.

I made a cardboard tube, running from the footwell ventilation outlet to the CEM, using masking tape to attach and seal it off. Even at 90+ degF, no A/C compressor operating and with fan setting 2 of 5 - and the kick panel removed to allow circulation - the problem has not re-occurred.

1) THANK YOU 2) THANK YOU 3) THANK YOU for this information. My old Volvo's knocking on 194,000 miles and I want to milk as many miles out of her as I can.

 

I'm very glad my installation log helped... However, unless you live in a spot in the country where you never run the heater, you'll bake the CEM if you ever do.

The best fix for this is cooling tines on the glue chips and a PC case fan. That way there is sufficient airflow over the circuits such that the heat of that air is less of a factor--you're pulling in cool cabin air along with the heated air from the vent. If you're exclusively using the airflow from the foot vent you'll only fry the poor CEM the first time you turn on the heat.

 

I live in southeast Texas and run the heat about 5 times a year, and only through the dashboard and defroster vents. Day/night temps in Jan & Feb are rarely below 50/35 degF, often warmer. Summertime? Day/night 100/78 are common in July and August.

Even fan setting #1 flows a good deal of air over the CEM through my jury-rigged contraption.

Thank you again, I am so happy to have solved this problem and in the process, saved Lord Only Knows how much $$.

 

1. Whats up can u send to me more pictures about it ? athalmeida387@gmail.com

 

Me too. My right turn signal, brake light and hazards don't work. I have multiple alerts popping up on the dash that are simply false, and I have been told with $1500 the dealer would replace the CEM for me.
I love my '02 V70 XC. It only has 122k on it and I was going to give it to my daughter. But it needs other repairs as well and I just can't afford it. Working turn signals are most important to me. So, how do I get started fixing this thing without cleaning out my savings account?

 

You can try just giving more ventilation to the CEM to see if that helps. I trust you have scanned the car (including the cem) to see what codes are stored in all the systems. That would be a good first step.

If you do have a CEM problem a company such as xemodex can help.

 

2004 V70 41K miles, I experienced all of the above. Shop sent out CEM for rebuild, all is well now. About $1,400.