2003 XC70 - intermittent electrical issues

[Porkchop32]

Morning all

I have a 2003 xc70 320,000 miles

It has an intermittent electrical issues which I will do my best to describe.
Car starts and runs well.
I have had the DIM,CEM,and ECM tested
seem to be ok.
Car starts everything normal then Abs, brake warning lights go on and off, but not always. Then the DIM goea out.
Things that don't function,
Locks, windows,driver's seat, rear windshield wipers and spray. Cruse control.
Ac compressor
On occasion the ac blower stays on even when the key is removed.
When I turn off the car and re start the only light is check engine which seems to operate normally.
After driven a while sone function return,
Ac blower and compressor, windows,door locks,driver's seat.
However the DIM doesn't come back to normal.
Battery and alternator are good.
This is an intermitting issue.
Any thoughts or suggestions would be most helpful
Thanks

[firstv70volvo]

Morning all

I have a 2003 xc70 320,000 miles

It has an intermittent electrical issues which I will do my best to describe.
Car starts and runs well.
I have had the DIM,CEM,and ECM tested
seem to be ok.
Car starts everything normal then Abs, brake warning lights go on and off, but not always. Then the DIM goea out.
Things that don't function,
Locks, windows,driver's seat, rear windshield wipers and spray. Cruse control.
Ac compressor
On occasion the ac blower stays on even when the key is removed.
When I turn off the car and re start the only light is check engine which seems to operate normally.
After driven a while sone function return,
Ac blower and compressor, windows,door locks,driver's seat.
However the DIM doesn't come back to normal.
Battery and alternator are good.
This is an intermitting issue.
Any thoughts or suggestions would be most helpful
Thanks

Most of these problems are related to the CEM and the low speed bus so if the CEM has checked out okay I would start with the fuses which supply power to the CEM. On the left side of the dash pull these fuses out; 14,22 and 32. Swap or replace these fuses with the same amp values (14 is 5A, 22 is 20A and 32 is 10A) and when replacing the fuses insert them and pull them out a few times to clean the contacts and use contact cleaner if you have some. These fuses all supply power to the CEM and assuming the CEM is okay there could be a low voltage condition on one of these supplies due to some resistance on the fuse contacts.
This is something that can be done quickly and easily so a good place to start. You could also include fuse 25 too as this is the power to the ignition switch and it wouldn't hurt to swap or replace this fuse and clean the contacts.
Try this and see how the DIM (and everything else) responds, the CEM controls the power to the DIM through a relay along with low speed communication so your DIM is most likely okay because most of the symptoms are CEM related. The ABS and brake warning lights in on the high speed bus but still from the CEM. After doing the fuse swap and contact cleaning I think you soon know if this helps or not.

If your problems seem to happen more after driving some and during higher temperatures here's a flowchart from Xemodex to go through

https://xemodex.com/us/pdf/DIM%20CEM%20 ... eMODeX.pdf

[SuperHerman]

Check relays and Shunts as well.

[Porkchop32]

Hi all
Thanks for the Ideas, for now it seems cleaning and replacing fuses as suggested is working I have driven several hundred miles without any issues.
Thanks again

[firstv70volvo]

Hi all
Thanks for the Ideas, for now it seems cleaning and replacing fuses as suggested is working I have driven several hundred miles without any issues.
Thanks again

Thanks for the update and let us know if this fix works longer term, hopefully it does.