GMC Troubleshooting Questions? Ask a Mechanic for Answers
Hello, Eddie here and I will do my best to help. On the back of the voltage regulator at the alternator, do you see a "GROUND HERE TO TEST" sign, and an arrow pointing to this screw? look at the picture in this diagram and let me know. Thanks.
OK, run a jumper wire, from the case of the alternator, (it's ground, any good ground like negative battery terminal if your wire is long enough) and ground that screw by touching the jumper wire to it. That will bring the alternator up to maximum output. Then you can see if your voltage stays at 14-15, and it should. Is the check engine light on now when driving? Also, does it die just at idle, like when you pull up to a stop light? or will it die going 50 mph down the road?