Loud clunk, wipers turn on, rear door ajar light turns on...Help!

trollins · Post by **trollins** » 22 Oct 2020, 14:01

I have a 2004 Volvo V70R. When we go on long trips there are times where we hear a loud clunk/bang that is very startling, then the wipers will wipe once, the dome lights come on and it says rear door ajar. If we continue driving, the loud clunk/bang will happen again, the dome light goes off and the door ajar light goes off, then when we turn the car off and then back on a check engine light comes on with about 30 DTC's and the car goes into limp mode. This happened one other time on a 90 degree day after about 5 minutes of driving.

The research I have done states the CEM gets too hot.

A gal who have an XC90 has the same issue, she had the CEM replaced but that didn't take care of her issue.

Any ideas? I love my V70R but now I don't like to take it on road trips, it just doesn't feel safe.

motormikeyman · Post by **motormikeyman** » 30 Oct 2020, 12:23

This sounds like a CEM or CEM related problem like a bad CAN connection. First thing would be to disconnect the battery and remove the CEM for a visual inspection. Look for water damage or corrosion. If none, clean the main connector and pins with electrical circuit cleaner. If this does not work, Xemodex has good diagnostics on their website for heat related failures.

Post by **BlackBart** » 30 Oct 2020, 12:48

But what is the physical clunk? Is that door ajar warning possibly related to it somehow releasing the hatch lock? I'm wild guessing here.

Post by **oragex** » 30 Oct 2020, 14:00

I would guess that clunk is a transmission bang. As above but rather than removing the CEM, just look with a flash light from underneath (may want to remove first the kick panel trim). Look for any wet or dry traces of water on the CEM module cover

trollins · Post by **trollins** » 13 Nov 2020, 10:53

motormikeyman wrote: ↑30 Oct 2020, 12:23 This sounds like a CEM or CEM related problem like a bad CAN connection. First thing would be to disconnect the battery and remove the CEM for a visual inspection. Look for water damage or corrosion. If none, clean the main connector and pins with electrical circuit cleaner. If this does not work, Xemodex has good diagnostics on their website for heat related failures.

Nothing is wrong with the CEM or CAN connection. No water damage or corrosion. Cleaned the connector and pins and used dielectric grease. I'll have to check their website because it definitely seems heat related. My husband put a heat shield around the computer and left the top off of the casing on our last road trip. It didn't do the weird clunk thing but when we got to our destination (about 4 hours) we turned off the car and went to use the key fob to lock the doors the fob wouldn't work. My husband knew that it set a fault, we have to disconnect the battery then clear the 30+ DTC's and then it's fine.

trollins · Post by **trollins** » 13 Nov 2020, 10:55

BlackBart wrote: ↑30 Oct 2020, 12:48 But what is the physical clunk? Is that door ajar warning possibly related to it somehow releasing the hatch lock? I'm wild guessing here.

No doors or the rear hatch are actually opened or released. I think the clunk is the transmission to be honest. But I'm not positive. When this happens it sets about 30+ DTC's with all sorts of module errors.

Post by **oragex** » 13 Nov 2020, 11:43

Transmission banging is a sign of CEM damage. If you can remove the wipers arms, look underneath for such upper connector corrosion. If you find corrosion, it means water has been leaking for a while on other internal CEM components

trollins · Post by **trollins** » 13 Nov 2020, 12:09

We will check this out. It's just strange that the issue only happens when it hot out or on long drives, not when it rains, but it's still worth looking at.

trollins · Post by **trollins** » 13 Nov 2020, 12:56

motormikeyman wrote: ↑30 Oct 2020, 12:23 This sounds like a CEM or CEM related problem like a bad CAN connection. First thing would be to disconnect the battery and remove the CEM for a visual inspection. Look for water damage or corrosion. If none, clean the main connector and pins with electrical circuit cleaner. If this does not work, Xemodex has good diagnostics on their website for heat related failures.

Oh my gosh...thank you, thank you for the Xemodex info. I believe I may have this problem finally solved. I knew it was an issue with the heat and the CEM from all the research I had done, I just wasn't sure how it could be solved. It looks as though Semodex repairs this problem. Waiting to hear from them, send it in and reinstall it. Keeping my fingers crossed because I love my car!!!