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Pete, Technician
Category: Volvo
Satisfied Customers: 28255
Experience:  Over 17 years diagnosing and repairing various automobiles at a dealer and independently.
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Volvo xc90: On Sunday I installed a trailer wiring harness

Customer Question

On Sunday I installed a trailer wiring harness on my 2006 Volvo XC90 V8 4.4 -- When connecting the wiring to the cargo area fuse box, via the power stud, the wrench tapped the frame and sparks flew. Now when the car is started there is an immediate error that the 'anti-skid service required' -then- after driving for a bit of time I see the 'Power system service urgent' with the red triangle and battery light. The battery voltage measured 12.3 while the ignition is off and a constant 13.5 when the ignition is on. Also (and not certain if this is relevant), the clock and trip meter reset each time the car is turned off and on. Most forums indicate that the 'power system service urgent' is typical of a failing alternator but I do not feel this to be absolutely correct given the circumstances of the trailer light installation as well as the constant 13.5v when ignition is on.

Main question:

What else could cause the power system service urgent error?

Side question:

Is there a means to diagnose that the CEM is at fault?


I also went through and took the DTC codes from the dash 'trick' :

DTCs set for:










Not checked for:








Submitted: 2 years ago.
Category: Volvo
Expert:  Pete replied 2 years ago.
My name is ***** ***** I am a professional here at Just Answer. I noticed that your question was not getting a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.
Clear out all DTC's and then try and operate the vehicle and see which codes come back in which computers.Once this is done post the code numbers here for each computer and code set so we can see what may be causing this fault here.
In some cases the codes just may need to be cleared out to correct this fault.
Thanks Pete
Expert:  Pete replied 2 years ago.

I am following up with you to see if you still needed help with your question you had asked.If my help didn't satisfy your question please let me know so we can continue.

Thanks Pete