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Mauricio, Technician
Category: Volvo
Satisfied Customers: 845
Experience:  15 years working in all makes and models
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Xc70: They replaced the alternator and battery

Resolved Question:

05 xc70. We brought my wifes xc70 to the mechanic because the battery had died unexpectedly a couple of times. They replaced the alternator and battery. After the work was completed the "Power System Service Urgent" warning light came on. The mechanic said he could not get it off. The said they recycled the system and called the local Volvo, but no luck. Any ideas what is wrong and how to fix it? Is the car safe to drive?
Submitted: 5 years ago.
Category: Volvo
Expert:  Mauricio replied 5 years ago.




The alternator on 2005+ vehicles uses a different regulator that the previous years. This should use an ACM (Alternator Control Module) style regulator which communicates with the CEM through the LIN-network.
If the alternator has been replaced, ensure the correct one was installed. An incorrect alternator will send 12 V on the Green/White wire. Normally, that wire will have square waves on it.

If an alternator was replaced with an incorrect,you could swap the regulator from the original to the new one without any problems.

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Expert:  Mauricio replied 5 years ago.

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Customer: replied 5 years ago.
I can check the check the voltage on the green/white wire with a standard volt meter?