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Discussion Starter #1
My daughter's '03 CTS is once again exhibiting gremlins. She called the other day and said some of her dashboard lights were coming on, then after a few moments, her radio shut down. A bit more, her blower motor went off, her windshield wipers slowed to sloth mode, and then nearly every warning light on the instrument panel came on with a warning that "electrical system needs maintenance." Sounded like an alternator to me, but I told her to have it tested. She was able to make it home but that was about it, and the car would not restart to get it to the garage for testing. I decided to go ahead and replace the alternator, but after removing it and going to the parts store, I asked them to test it and they said it tested good. (I watched.) The battery is only 1 month old, but after taking the old alternator back and re-installing (Grrrr.) we had the battery checked and it was dead. They charged it up and it tested good. The car subsequently started up and ran fine. For about 24hrs. Then warning lights started appearing again.

The parts store tell us that it is probably the PCM/ECU that needs replaced. Her mechanic at the garage tells her "no way" because the car wouldn't run if it were. I disagree with both of them. I disagree that it has to be the PCM because it seems very obvious to me that the alternator is not charging the battery. I disagree with the mechanic because a PCM does not have to fail entirely. (Witness the 2000 Infiniti in my driveway.)

So, opinions please. I told her to take the car to the garage and have it tested to see if the mechanic can prove his theory. She doesn't want to spend the extra dollars on the test if it's still going to say the alternator (college student reasoning), but I say it's better than buying the alternator and then finding that you still need the PCM. Your experienced advice is appreciated!

Thanks!
 

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cts
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Discussion Starter #2
I've probably answered my own question here, but I was just wondering if anyone had experienced this before and if so, what did you do? There are no codes showing when we check, so does this mean that the alternator is likely the problem?

~Darrin
 

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2003 CTS
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What does the voltage show in DIC display when the car is running? Should be low 14s ... If so alternator is charging battery. Its a 03 so you can check codes right on the radio..no tech11 tool needed to diagnose.
 
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