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Old 03-14-2019, 09:51 PM
JAL71TA JAL71TA is offline
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Default Generator light on

Needs some advice... generator light is on in my dash and the generators tests out ok, Next step is to test the voltage regulator but how often do those really go out? Any other suggestions on what could be wrong and the solution?

Jim

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Old 03-15-2019, 01:18 AM
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Verdoro 68 Verdoro 68 is offline
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I had this problem a few years ago. It was due to a defective reproduction wiring harness. Maybe a bad dash ground or a blown fuse?

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Old 03-15-2019, 03:08 AM
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Is it on steady and bright, or does it fade in and out?

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Old 03-15-2019, 09:06 AM
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Stays on steady without any flickering.

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Old 03-15-2019, 09:07 AM
JAL71TA JAL71TA is offline
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Wiring harness is the original one to the car.

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Old 03-15-2019, 12:13 PM
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If the light stays on steady and the alternator output is good. As others have said, I'd suspect the wiring, fuse or ground. Some smart guy with a wiring diagram could probably find the likely suspect.

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Old 03-15-2019, 12:22 PM
JAL71TA JAL71TA is offline
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Thanks for the tips, I'll look at the wiring and fuse a bit harder to see if that my problem. Appreciate the help.

Jim

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Old 03-15-2019, 01:26 PM
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Had this issue once. Alternator functioned perfectly. Turned out to be the voltage regulator that was keeping the generator light on.

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Old 03-15-2019, 01:36 PM
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Great suggestion as well.

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Old 03-18-2019, 07:13 AM
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I would check all the wiring to the regulator. There is a wire in that regulator harness that feeds a ground to the light & then flips & provides voltage when charging that puts the light out. Not sure what one off hand. you could also have a bad regulator, even though your getting correct voltage when running.

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Old 03-18-2019, 08:48 AM
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Check fuse

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Old 03-18-2019, 09:43 AM
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I beleive if its a fuse, the light only comes on when its running, but off when just the ignition is on. Could be wrong on that, but I believe that's what happens.

The function is pretty simple though, the light bulb has power from the fuse block on one end & finds ground through the regulator. When the engine is running, voltage is then produced from the regulator & the ground the bulb had turns into what ever voltage is coming from the charging system. IE 13.5 +/- Because this same voltage is going to the fuse block, both sides of the bulb see the exact same voltage & the light goes out.

Most of you guys know that already, but seems worth mentioning, because it makes trouble shooting it so much easier. Anybody have the wiring diagram handy? I have it at home & can post later, but I want to say it was a brown or tan wire between the regulator & bulb.

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Old 03-18-2019, 09:48 AM
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Thanks for all the help, issued fixed. It was a combo of bad fuse and loose wiring to voltage regulator.

Appreciate everyones input, cut down on the time to fix for sure.

Jim

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Old 03-18-2019, 01:29 PM
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Excellent!

And ragtop ... excellent explanation of how the light worked, I had no idea it was that simple.

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Old 03-27-2019, 08:41 PM
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Something I never noticed until tonight. When you shut off the engine, the bulb finds ground from other circuits right when the power is cut from the ignition switch. Because the engine is still momentarily turning the alternator, the bulb lights until the alternator stops turning & making power. Complete opposite of when you have the ignition switch on & engine not running. Bulb lights in both cases, just reversed polarity.
Thought it was worth mentioning.

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Old 09-17-2022, 07:33 PM
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Which fuse was bad?

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