I added a heatsink to my 2004 CEM CPU

**robert240** · 04-21-2015, 11:35 AM

One common issue with my 2004 (and other years) is the CEM CPU overheats on hot summer days. Basically all interior controls go dead except for the fan, but the car will continue to run and drive. I purchased a 1" square heatsink with adhesive backing for $7.50 from Digikey.

**Forkster** · 04-21-2015, 01:15 PM

robert - thanks for posting...what was the Digikey part number? Also - how did you remove it? Did you also have to remove all the other plugged in components to get at the CEM? This applies to all 2001-2004 Volvo XC70's. In 2005, Volvo added a heat sink to the CEM but did nothing for the 01-04 owners...

**robert240** · 04-21-2015, 02:20 PM

Hello, the Digikey part number is ATS1200-ND:
http://www.digikey.com/product-searc...rds=ats1200-nd

I had to remove all the shunts and relays to remove it, then the top plastic cover and the top metal lid. I learned the removal/install procedure from this video:
https://www.youtube.com/watch?v=lRdXsCdvhVg

**goldxc70** · 05-05-2015, 10:57 AM

So I had some time today and decided to have a look at this job. While I don't have the recommended heatsink, I have a lot of other hardware around and thought I could adapt something to the job. Had no problem getting the CEM out. Here are a few images:

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There is a big blob of varnish/coating on one corner of the large chip that well need to be cleaned off for good heatsink contact. It also occured to me that just leaving the silver cover off might improve the cooling of the large chip. Anyway, had to put everything back together in a hurry to make a run. Issue is still there but I'll update this thread as soon as I pick up and install that heatsink.

**djrichard** · 07-12-2015, 12:58 PM

Originally Posted by goldxc70

There is a big blob of varnish/coating on one corner of the large chip that well need to be cleaned off for good heatsink contact. It also occured to me that just leaving the silver cover off might improve the cooling of the large chip. Anyway, had to put everything back together in a hurry to make a run. Issue is still there but I'll update this thread as soon as I pick up and install that heatsink.

Would be interested in knowing whether people have removed the blob of coating on the large chip. It didn't look easily soluble, so I just put the heat sink right over it and the rest of the chip.

Would also be interested in knowing if people put the silver cover back on. I left it off. Maybe it's there for Electro-magnetic interference issues?

I'll post back up if I needed to go to plan B.

**Forkster** · 04-22-2015, 11:52 AM

Thanks Robert - I've just ordered one for my 04. Will follow the same steps in the video too...been a PITA for over 5 years now.

**xcbody** · 04-23-2015, 12:02 PM

Did it work? any problems since?

**robert240** · 04-24-2015, 08:44 AM

no problems since but it hasn't gotten hot here yet.

**djrichard** · 08-23-2015, 11:45 AM

Originally Posted by xcbody

Did it work? any problems since?

In my case, I added the heat sink and the problem occurred again. So I'm curious, should I put a heatsink on the 2nd chip inside the metal-ringed area as well? E.g. I noticed that xemodex uses two heatsinks; see 6:30 mark: https://www.youtube.com/watch?v=lRdXsCdvhVg#t=6m30s

Withstanding that, I'm thinking of giving up and working directly with xemodex . I can see they add the heat sinks and some kind of rubber proofing on top of the circuit board. Anything else they do to the CEMs to rehab them?

Or does this maybe suggest my issues lie somewhere else, e.g. the DIM?

The DTCs I get seem to be the same bunch as what others get with the over-heating CEM. And my car lurches/stalls like in this video: https://www.youtube.com/watch?v=fMGvLQhU_Fw#t=69 . Except the root cause in this video seems to be water related. And I'm pretty sure my issues are not water related. That said, the lower corner trim on my windshield is eroded pretty badly, but I don't have any water coming in the car interior. At worse, when I pour water over that spot, it goes into the front quarter panel area (as well as the cowling duct). But again, I didn't see any water get into the interior where the CEM sits.

Thanks for any thoughts!

**djrichard** · 08-23-2015, 12:12 PM

Originally Posted by djrichard

Withstanding that, I'm thinking of giving up and working directly with xemodex . I can see they add the heat sinks and some kind of rubber proofing on top of the circuit board. Anything else they do to the CEMs to rehab them?

This part answered here: http://xemodex.com/us/product/centra...0657629-00-22/

THERMAL COOLING UPGRADE

All CEM’s have a heat dissipating sink installed directly on the MCU. This upgrade will ensure reliable processor operation during hot summer months.

COMPLETELY REWORKED PCB

All internal circuit boards are tested at the component level. Any known prone to failure parts that are close to the maximum tolerance are automatically replaced.

PCB CONFORMAL COATING UPGRADE

The circuit board is coated with conformal coating to help prevent damage to the components in the event of water intrusion.