Here is a timeline of what has happened since I got this car a month ago.
2007 Volvo XC90 V8 173,000 miles
-Bought with anti-skid service light was on, which I read was normal.

-Later found out the rear wheels actually do not spin when front spins in snow, Possibly haldex oil pump on rear differential. I'll dig into this later this year.

-3 days after purchase, “Coolant low, stop safely” light turned on. However, coolant level looked fine. I turned off the car and added more. Turned the car back on and the warning was off.

-3 weeks later, After a car wash “position bulb failure” warning, but no bulbs were out. This warning light turned off after a few minutes. Weird.

-1 week later after a car wash I drove 5 miles and got the “system power failure” warning, along with the red battery light. This turned off within 2 minutes and the car started fine the next start up.

-The next day after driving 5 miles, “system power failure” warning again, turned off within 2 minutes.

-That evening, after car sat outside in a wet snow storm~2hrs, during a 20 mile drive home:

-System power failure

-Passenger airbag off

-Windshield wipers seemed to slow down??

-Headlamp failure service required. (turning headlight button was blinking)

-“Transmission failure service required” (Car would not shift down from 5th gear, not even manually).

-I stopped the car when I got home and turned it off then would not turn back on, it would click and some lights would flash. Sometimes it would sound like it would try to fire for a second but would not turn over, check engine light flashed.

-The next morning after some research, I figured I would check the CEM terminals. I got in the car and it started fine. I drove down the driveway, shifted fine into all gears smoothly. I then parked the car and took out the CEM. All terminals seemed to be clean, not any visible corrosion. I still sprayed and cleaned connections with electrical contact cleaner. I put the CEM back into the car and started it up.

-“Coolant level low, turn off engine" warning light turned on, level looked fine.

-“Position Bulb failure” turned on, no lights were out.

-“Brake failure” warning turned on.
-"Passenger airbag off"

-I turned the car off, and it would not turn on again just as it did the night before.

I guess my next questions are:

-Does this actually sound like a CEM problem?

-Can the CEM be bad even if the connections are not corroded?

-Is there anything I can do to confirm this before ordering a new CEM from XeMODeX?

-What are my next steps?



Thanks for your input!

 

Start simple, do a battery load test, a charging system check and check the battery connections.

 

-Anti-skid light is not normal. You need codes read. Could be related to the AWD not working.

-Coolant may have been slightly low or you could have a failing level sender or stuck float.

-You have a taillight bulb or rear bumper marker bulb out.

-You likely have a failing alternator. Common on the V8. Low system voltage can cause all kinds of problems. I doubt its a CEM issue.