CEM issue?

[ibs740]

Hi all,
2004 V70, 2.4, NA, 5sp
I was sitting with key accessory on listening to radio. Low battery warning pops up (time for a new battery or check liquid level).
I started car and it idled for 10+ minutes. Steady rain around 3C.
Smelled a nasty acrid burning smell, didn’t notice the DIM (instrument cluster) had no lights right away.
Drove off, no DIM lights at all and climate lighting and function also not working. Everything else worked.
Checked it the next day and got the the following codes;
DDM0030, DDM0024, DDM002B, PDM0024, PDM002B, CEM8F43,
the above pop up every once in a while if I check for codes but never trip the check engine light.

The following codes are new and never seen before;
CEM6C48, CEM3A04, CEM6A03, CEM6A01, CEM 1A54, CEM1A55, CEM1A56

Fuse #24 was blown, I replaced it and popped as soon as I turned the key.

I started the car with #24 not in place, while still running I installed the fuse. DIM and climate system lights and operation come to life. Everything works.

I could move the drivers back (access to CEM) only if I locked the car then unlocked with the FOB then used the seat controls. Switching to accessory, the seat wouldn’t move.

I started and stopped twice more (VIDA check for current codes, turn ignition off, start and rev above 1500rpm, turn off, start and idle for 20sec)

I got a warning light in red; “SRS airbag service urgent” I cleared all codes and checked with my PPC Diagnostic reader and no codes came up.

I had a look for what caused that burning smell and nothing is obvious.

Plugged VIDA in again today (car starts and runs fine) VIDA showed DTC SRS-00D5 and text in DIM window is normal colour, VIDA shows it as yellow fault.

SRS warning lamp lights on key pos 1 and all lights (incl SRS) work on pos 2 and go out after car starts.

Ran thru VIDA checking the SRS-00D5 code fault it came up with 2 suggestions;
1. possible open circuit in CAN cable (source of my smell?)
2. Faulty combined DIM

VIDA gave me a bunch of #'s for DIM ECU, DIM CAN, DIM SW, etc I assume that tells me the components validity???

I find VIDA is the typical designed by a programmer software with me doing the cat in a box approach as I'm a tad clueless with electronic gremlins.

I seem to remember something about the CEM can't do self diagnosis.

I picked up some manual reset auto style fuses, figured popping lots during this. Some whittling is required as the ones I got are
a little wide to easily fit into the Volvo fuse panels.

Any help is appreciated.
thanks

[firstv70volvo]

With fuse 11C/24 blowing I would first check the CEM for moisture and pulling relay CMI22 to check the contacts and for any moisture in that area. You could also swap this relay with another one of the same type for troubleshooting. I seem to recall reading there were some model years where water was getting to the CEM and why I'm suggesting checking the CEM for moisture.

The CEM controls relay CMI22 (extended D1 power) and the relay power source comes from fuse 11C/24 and when the relay is closed it supplies power (extended D1 power) to the CMM, DIM, PSM and CPM modules. The power seat module would also be another area to check for moisture and when checking these different modules use your sense of smell for any lingering burnt electrical odor to try and determine if one of the modules may be damaged. The SRS light/codes could be due to one of the modules being damaged or losing the ext D1 power to the modules. see pdf

CMI22 relay power fuse protected from 11C.pdf

(455.74 KiB) Downloaded 761 times

What's going on with fuse 24 now, it is still blowing? You're going to see a lot of codes if the fuse blows because it supplies power to four modules and CAN communication will be interrupted as well.

[ibs740]

Fuse 24 only blew the once. Replacement has stayed intact.
I'll check out your great ideas and post back.
Thanks
ian

[ibs740]

I pulled CEM and every relay on it. zero burnt smell or sign of moisture, dry as a chip. No moisture signs anywhere under dash or carpet. Checked the bits under the drivers seat and seat/window module in the door. All good. Did the CEM reset (disconnect neg at battery and hold against the positive for 15 minutes. Cleared codes (lots of CEM codes), Started it up and no SRS warning light, it's gone.
Will take for a test drive latter. I need a new battery but what was that smell?
Thanks for the help.

[firstv70volvo]

I pulled CEM and every relay on it. zero burnt smell or sign of moisture, dry as a chip. No moisture signs anywhere under dash or carpet. Checked the bits under the drivers seat and seat/window module in the door. All good. Did the CEM reset (disconnect neg at battery and hold against the positive for 15 minutes. Cleared codes (lots of CEM codes), Started it up and no SRS warning light, it's gone.
Will take for a test drive latter. I need a new battery but what was that smell?
Thanks for the help.

The burning smell and fuse blowing are likely related but whatever the shorted condition was seems to no longer be a problem. At least it appears none of the modules are damaged or I would think you would see some codes and symptoms continuously. Good to hear no moisture was present too. Battery condition is crucial when trying to troubleshoot any electrical problem so best to replace a bad battery and eliminate this variable, which can cause all kinds of additional problems.

[ibs740]

Off to Walmart to get one of their 900 CCA batteries from Johnson Controls or whomever bought them.
Nice thing about these bricks is lots of room for the larger battery
thanks again

[abscate]

Off to Walmart to get one of their 900 CCA batteries from Johnson Controls or whomever bought them.
Nice thing about these bricks is lots of room for the larger battery
thanks again

All batteries are now Taco Bell