electrical issue
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2nd Gear
Joined: Aug 2021
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electrical issue
Just changed out the alternator on my 79 after the old one checked at 11.8v under load. However I still have an issue when I turn on the headlights as voltage will drop about .4v and when I brighten the dash lights to maximum the voltmeter will drop to almost 0v even though the alter is putting out 13.8 0r so. suspect the circuit board behind the guages as the light switch and ground are new. Anyone else run into the same problem?
Race Director
Joined: Nov 2006
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From: Sunshine Coast, Queensland, Australia
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Cruise-In VIII Veteran
3 wire or 1 wire alternator? With a 1 wire alternator I would expect a slight voltage drop when you switch on the lights.
.with a 3 wire alternator correctly wired up I wouldn't expect much of a drop.
As per your volt gauge reading zero? Could be a number of things. I'd start with the printed circuit board the gauges are wired with.
.with a 3 wire alternator correctly wired up I wouldn't expect much of a drop.
As per your volt gauge reading zero? Could be a number of things. I'd start with the printed circuit board the gauges are wired with.
Race Director
Joined: Nov 2006
Posts: 13,151
Likes: 7,765
From: Sunshine Coast, Queensland, Australia
2025 C3 of the Year Finalist - Modified
2024 C3 of the Year Finalist- Modified
2022 C3 of the Year Finalist - Modified
Cruise-In VIII Veteran
Oh, and 13.8 is a bit low.
Le Mans Master
Joined: Jan 2001
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brian holwell
Take some readings at the battery terminals.
Voltage at idle.
Voltage say 1500 rpm.
And go drive around with the voltmeter hooked and see what it reads.
That should give us a little better idea of how the alternator is performing.
Take some readings at the battery terminals.
Voltage at idle.
Voltage say 1500 rpm.
And go drive around with the voltmeter hooked and see what it reads.
That should give us a little better idea of how the alternator is performing.
Just changed out the alternator on my 79 after the old one checked at 11.8v under load. However I still have an issue when I turn on the headlights as voltage will drop about .4v and when I brighten the dash lights to maximum the voltmeter will drop to almost 0v even though the alter is putting out 13.8 0r so. suspect the circuit board behind the guages as the light switch and ground are new. Anyone else run into the same problem?
