A few weeks ago I posted about an Alternator Problem that I was having....I had replaced three Alternators in three weeks that had all quit when the car hit 5,000 RPM....I finally broke down took car to dealer they put what they called "Remanufactured GM" with Lifetime warranty...THey claimed they found a loose connector on the alternator cable...I was sckeptical since I had touched that connector six times while changing the other three alternators, but figured I'd try it...Two days after I brought the car home, same thing hit 5,000 RPM alternator quit and wouldn't charge again...Tool it back to the dealer, they have had it for four days and can't find the problem.....

However they did tell me that ehy found the following code: DTC P1637

The powertrain control module (PCM) uses the generator turn on signal circuit to control the generator. A high side driver within the PCM allows the PCM to turn the generator ON and OFF. When Generator operation is desired, the PCM sends a 5 volt signal to the voltage regulator via the generator turn on signal circuit. This causes the voltage regulator to begin controlling the generator field circuit. Once the Generator is enabled by the PCM, the voltage regulator controls generator output independently of the PCM. Under certain operating conditions, the PCM can turn Off the generator by turning Off the 5 volt signal on the generator turn on signal circuit. The PCM has fault detection circuitry which monitors the state of the generator turn on signal circuit. If the fault detection circuit senses a voltage other than what is expected, this DTC will set. The voltage regulator also contains fault detection circuitry. If the regulator detects a problem, the regulator will ground the generator turn on signal circuit, pulling the voltage low. This also causes the PCM to set the DTC.

Does anyone have any insigt they are willing to offer???????

 

With the other alternators you went through, did you get them tested out of the car after they quit on you and not just going by the car's volt gauge? I'm wondering if your PCM is maybe the problem. Then when you change the alternator, you are also disconnecting battery power which could be resetting the PCM? Just a theory.

 

Yes, I am getting them tested the most they will put out is 11-12 volts........I am thinking that my problem could be the PCM, or my fear is that I may have a bad ground (wire) in that lengthy wiring harness from the PCM.......PCM though expensive is an esy repair, tracking down a bad wire is a nightmare