Volvo Repair: Service engine light - cause, service reminder, proper diagnosis

Question
Roger,

Thanks in advance.  An S80 displays the service engine light.  The dealer and an independent have both diagnosed the car, and have 2 different opinions: Dealer says battery and voltage regulator, independent says it's the ETM module.  Any suggestions to get the definitive (and correct) answer?

Thank you.

Answer
Rick, how can anybody diagnose those cars without scanning it on the computer.  If you mean the service light, that is just a service reminder and can be cleared manually.  If you mean "CHECK ENGINE" that is something that needs to be scanned first.  Both of these shops are being jerks.  Somebody needs to scan the car and give you the proper diagnosis.  Roger