non-expert needs help diagnosing a 2004 s80
 

I have a 2004 s80. The previous (and first) owner was literally a little old lady (my mom!) who took impeccable care of the car. She got it serviced at the same Volvo dealer, and before I got it she took it in for one more "clean bill of health." It was in the garage for a couple of years, with fairly frequent start-ups (turn it on, leaving it running for 10 minutes, drive it around the driveway, etc.). All was good when my son started driving it, then we had problems. Here's a description:

• all dash lights are off except for climate controls and radio.
• when I start it up, the "check engine" light comes on.
• all of these DO NOT WORK:
  • high beams
  • blinkers
  • cooling
  • keyless locks
  • and the engine lost all thrust - could barely get up our (steep) driveway
• all of these WORK
  • headlights (no high beams)
  • climate/fan (but no AC)
  • radio
  • power windows

It has a new battery (within the last couple of months). One other thing to note is that my son uses one of those bluetooth adapters that plugs into the cigarette lighter and plays music through a low-FM channel. I can't imagine that's causing our problems, but I have no other ideas. I've heard it could need a new CEM (the main computer for the car?) but I'm hesitant because a) it's expensive, and b) I'm not sure it will fix the problem.

THANK YOU so much if you can offer any advice.

If you have a volt meter (even a $25 Harbor Freight unit) you can do some tests.

1) start with measuring battery voltage (engine off). should be 12.5V give or take a tenth. Start the car - measure volts - should be 14 or so.
2) Next inspect all fuses.
3) rent/borrow an OBD2 code reader (Autozone etc often do this). Find the connector port under the drivers dash. Plug it in, turn the key to position 2. Scan and write down all the codes and start googling.
4) with the key at position 2 - try wiggling it to see if any dash lights flicker... (ie possible issue with ignition switch) also try wiggling the multi-function stalk (aka directionals). Check out Youtube for vids on how to replace these parts.
5) Has the car experienced any water leaks like wet floors after a rain? Google for the location of the CEM for your model. CEM is the central electronics module which houses relays for various devices. Check to make sure its connectors are clean (use electronics cleaner on connectors and slots) and fully inserted.
If your CEM is indeed bad, check out XeModex web site for common symptoms and costs to rebuild your unit ($250 or so).

After that you may need to probe around at various wiring junctions etc so that may be when its time to call in a pro.

thanks very much for all the helpful info. I will try these steps.