I added a heatsink to my 2004 CEM CPU

[sanfelice]

I see that you used one with adhesive. I wonder if thermal paste would work in this case.


I wished I had known about this trick when I had my 760 TI many years ago; that thing would constantly blow ignition modules from heat and you would be STRANDED! (as I was in the middle of rush hour traffic in NYC on the West Side Highway...)

[Greg Wong]

This is pretty funny, my company makes that heat sink.

This one would keep it just a little bit cooler, as long as the spread fins fit in there.
http://www.digikey.com/product-detai...101-ND/1284815

You can't use thermal paste on this, you need an adhesive to keep the heat sink in place.

Oh, even better, go to Mouser.com and search for 984-ATS-52250B-C1-R0. This is the same heat sink as above, but the thermal tape is a newer version that sticks better and has better thermal performance.

Greg

[goldxc70]

I see that you used one with adhesive. I wonder if thermal paste would work in this case...

Thermal paste and adhesive thermal pad do the same job with one exception: the adhesive pad holds the parts together while the thermal paste does not.

[goldxc70]

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:




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.

[BMac_R]

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.

Robert. I am currently in love with you for setting up this thread. About 6 months ago I ran into an issue with my monitor reading "Left Rear Door Open" with all my interior nights starting up and illuminating. I have had instances where all the dash has shut off and upon shutting down the car and locking the doors the car would be dead. No unlocking of door with Key Fob wouldn't start with key. Remove the battery terminal for 10 seconds, reinstall and boom the car comes back to life. Now that the weather is kicking back up......the problem is back and I was about to pay $450 to get the heatsink installed and lacquer coating installed on a used unit with the program transfer. Before I get to attempting this myself could you inform me as to whether this was successful or not to fix your CEM issues? Also, could you email me the full version of the final product pictures as the forum isn't working for me? [email protected]

[djrichard]

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.

[Scopeman]

The cover will certainly shield the EMI radiation from the CEM, it also provides the obvious physical protection. I doubt there will be a problem from any EMI though.

[Forkster]

The Xemodex rebuild removes the silver cover...EMI interference? Unlikely unless it was next to a large electrical generator from a hydroelectric dam.

I left mine off and it had no issues right up to when I sold it to Darcy.

Ed

[Scopeman]

The problem is not EMI/RFI going into the CEM. it is that coming out of it. Digital systems create lots of broadband noise. Now, if the driver has an amateur radio transmitter installed in the vehicle, then it could cause a problem with the cover off.

[djrichard]

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!