Duramax Diesels Forum Truck of the Week
Old 07-12-2018, 03:27 PM
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Mike L. Mike L. is online now
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My '16 GMC 1500 does this on a regular basis. I watch my amp guage drop from time to time and dash lights dim. Owners manual says it's normal. I hate it.
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Old 07-12-2018, 05:17 PM
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Originally Posted by Mike L. View Post
My '16 GMC 1500 does this on a regular basis. I watch my amp guage drop from time to time and dash lights dim. Owners manual says it's normal. I hate it.
1500's have had it since around 03 iirc. They can drop down to 12.8 cruising on a hot day with the headlights off. I know that Chrysler starting back in the late 90's started putting battery temp sensors into many cars, and later into trucks. They would start out at 14.5-14.8 volts, once the battery got up to 100 or higher, the charging voltage would drop down to 12.6-13.2 volts. The difference was with them, the volt meter didn't drop below 14 volts on the guage. There guages were worse than GM's for being glorified idiot lights.
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Old 07-12-2018, 05:35 PM
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My LMM seems to do it to. Not sure if it supposed to but it is much better now since I installed a second (dumb) alternator
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Old 07-12-2018, 05:50 PM
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Could be worse. I put an alternator on a 2015 6.7 F550 that just ran until it shut off. No battery lights or messages. It popped up "low fuel pressure", a/c quit and it ran another 15 minutes or so and died. According to the owner battery light never came on. Wasn't on while I was doing diag either.

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Old 07-12-2018, 08:33 PM
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I think at this point I'm just going to accept it as normal until I find something that clearly states otherwise.

Even at 13.2 I can't get it to change no matter what accessories I turn on.
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