I have a 2000 Chevy Lumina with 191k on it. While drive between Casa Grande to Masa last weekend, I noticed the AC stopped blowing air. Thinking it was the compressor that went out, I turned off the ac and rolled down the windows and kept going. Turning onto US60, the cruise control kicked out and wouldn't go back on. When I took my exit, I noticed the engine surging, no turn signal, and clock on radio was out. It had trouble shifting and no lights. I limped it home and found that the battery was dead. Charged up the battery and took it to a garage and they said the alternator was bad. Replaced the alternator and two days later, the volt light came on and the same thing started to happen. I was closer to home and not as much turned off. I have a good ground and 13.8v off the battery when charged and off the alternator. There's a wire from the alternator to the computer that tells the alternator when to turn on/off the regulator. I'm suspecting the computer. The Haynes book says it might be the computer, the parts store guys says it's likely the computer, but when I take it to three different mechanics to have them test the computer, they want to test everything except the computer. It's $120 for a new computer and I can take it in and out myself. I have enough money to either take it to another mechanic but not buy the part, or replace the part but not take it to a mechanic to confirm it's the computer. Right now I have a dead car in the driveway and one running car for three drivers. Any advise/recommendations?

 

There was an issuenon another thread recently that addressed a broken wire to-from the alternator to ecm. Check your harness from the alternator. More than likley it is NOT the ECM. I am not up on the "newer" stuff, but the alternator might have a plug to it and marked either F or field on the alternator at the connection. That is the field wire to the alternator that controls the ouput voltage from the alternator. Why GM wouldn't stick with an internal voltage regulator is beyond me.