| ALT High Voltage output [message #118994] |
Wed, 16 March 2011 13:06  |
Jon payne
Messages: 495
Registered: May 2008
Karma:
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Guys,
Recently I went to the barn to check on the GMC and wake her up from hibernation. I started it up and while she was warming up all of the sudden the interior lights went really bright. I checked the voltage on the monitor panel and the volt meter was pegged, passed 18VDC. I have experienced this once before on a Chevy Malibu I had and found the the alternator VR was bad. Thinking this was the same situation I removed the alternated and had it tested at Autozone. The test showed the alternator is good. Later I found out that it could be the generator output diodes, AKA battery isolator.
I have not checked the isolator yet, but since the house battery is removed (for the winter) how can the isolator cause high voltage on the DC system? Where would the increased voltage be coming from?
Trying to understand this better it would be helpful to know where the volt meter on the monitor panel reads voltage from? Looking at the wiring diagrams in the manuals I could not find the monitor panel.
I am thinking my alternator could still have a problem but intermittent. What do you guys think?
Jon
Jon Payne
76 Palm Beach
Westfield,IN
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