Bizarre electrical symptoms 04 Xc90 SOLVED

850TurboTurtle · Post by **850TurboTurtle** » 13 Jul 2026, 13:28

***SOLVED: the main ECM is dying. Apparently radio problems are often early signs. We will have to get a replacement ECM programmed by the dealership.***

Last week I tried the radio (after getting car back from the shop for a bumper repair and detail). The head unit turns on and responds to all controls but the power amps did nothing. No sound. So I thought maybe the retailers had bumped some audio connector vacuuming under the seats.

Returned to shop today. The radio made a couple of odd pops while driving so powered off the head unit.

Shop checked the car and radio, no electrical codes when scanned. But same symptoms I had seen.

I suggested they check the connectors under the seat. After a half hour the technician came back and said the car now won’t start, the dash panel won’t come on, and it’s driving in limp mode stuck in first gear. Nothing electrical is working except the cigarette lighter.

What the heck? This is the most reputable shop in town, not a hack garage. What could be causing all this damage?

850TurboTurtle · Post by **850TurboTurtle** » 13 Jul 2026, 13:36

We’ve had the car 18 months with zero problems and have made no changes to it other than taking it in 3 weeks ago to get the rear bumper replaced (someone dented it a few months back and they finally got the parts).

Vova585 · Post by **Vova585** » 13 Jul 2026, 15:21

My bet would be on "detail" job. It is an old car and should not have much of communication wires inside of the bumpers,maybe a proximity sensors if equiped(not sure about 2004MY). Ideally would have a Vida to read the car and see what the car is fussing about and what code happened first. Maybe cheapest solution would be to try to dry the car on hot sunny day with all windows and doors open. Move all the carpets, mats and see if anywhere you have a pooling water which could get into Can-bus system connector. But without scanner it would be a hard guess job.

Capndirk · Post by **Capndirk** » 14 Jul 2026, 08:28

Maybe the detail job allowed water into the CEM connections? Especially if there was a pressure wash of the cowl and engine spaces. It's somewhat common that water intrusion into the CEM connector causes several random, unrelated electrical faults. If you get to it soon enough, it may be possible to dry the connectors and CEM and prevent corrosion.

Post by **cn90** » 15 Jul 2026, 07:50

Same problem with my 2006 S60 radio (no sound)... apparently from a bad amplifier volume chip.

A "new" radio from the junk yard solved the problem.