Simple GEN light question
Thread Starter
Cruising
Joined: Feb 2013
Posts: 11
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Simple GEN light question
Here is an easy one, should the GEN light be on when I turn on the ignition.
Why you ask? American Corvette is not my first language, air-cooled VW is, so I'm learning as I go. I don't get a GEN light when I turn on the ignition, when I start the car, at idle, it isn't charging, but not light. If I tap the gas, speeding up the engine, the GEN light comes on. I believe you need the GEN light on before start, so power gets to the 1 terminal of the alternator to Excite it. I have power to the Main terminal, as well as the 2 terminal. But mV to the 1 terminal when I turn on the ignition.
Am thinking correctly? Or am I completely off base.
Why you ask? American Corvette is not my first language, air-cooled VW is, so I'm learning as I go. I don't get a GEN light when I turn on the ignition, when I start the car, at idle, it isn't charging, but not light. If I tap the gas, speeding up the engine, the GEN light comes on. I believe you need the GEN light on before start, so power gets to the 1 terminal of the alternator to Excite it. I have power to the Main terminal, as well as the 2 terminal. But mV to the 1 terminal when I turn on the ignition.
Am thinking correctly? Or am I completely off base.
Race Director
Joined: May 2006
Posts: 18,598
Likes: 2,540
Your understanding is correct. Check to make sure the #1 wire isnt broken inside the insulation.
http://bob_skelly.home.comcast.net/~...ternator1.html
http://bob_skelly.home.comcast.net/~...ternator1.html
Thread Starter
Cruising
Joined: Feb 2013
Posts: 11
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Great site there.
There was good continuity at terminal 1.
I bypassed the "stock" wire, and place a jumper, with light in place, hooked the wire to a power source. Light came on, started car, light went off, and it started charging. For some reason I'm not getting power to the GEN light, and therefore not exciting the alternator.
At least I know what, now I need to find out why.
Also when everything was hooked up, my voltmeter was reading nothing, below 8. I don't know where the voltmeter gets power, or if it is associated with the GEN light in anyway.
But still open to advice
Rich
There was good continuity at terminal 1.
I bypassed the "stock" wire, and place a jumper, with light in place, hooked the wire to a power source. Light came on, started car, light went off, and it started charging. For some reason I'm not getting power to the GEN light, and therefore not exciting the alternator.
At least I know what, now I need to find out why.
Also when everything was hooked up, my voltmeter was reading nothing, below 8. I don't know where the voltmeter gets power, or if it is associated with the GEN light in anyway.
But still open to advice
Rich
Le Mans Master
Joined: Oct 2006
Posts: 7,123
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From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
78 Wiring diagram: http://www.nrjvette.com/johdotukset/...tte%201978.pdf
Quick look, it appears that the brown wire comes right off the ignition switch, thru the bulkhead and to the alternator.. As I said, quick look. If that is the case, then possible bad contact in the switch.
Quick look, it appears that the brown wire comes right off the ignition switch, thru the bulkhead and to the alternator.. As I said, quick look. If that is the case, then possible bad contact in the switch.
Le Mans Master
Joined: Dec 2007
Posts: 6,422
Likes: 591
From: McHenry Illinois
Only the earlier cars without a gen light were wired that way (brown wire to ign.) On the 78, the gen light bulb is in the circuit, if the bulb burns out, it stops charging. Could be an issue with the printed circuit on the back of the small gauge cluster or maybe a break in the wire between there and the alternator.
Thread Starter
Cruising
Joined: Feb 2013
Posts: 11
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Thanks for the posts.
Here is the latest. As I said, I got it to work with a "Temporary" GEN light and wire. I hooked back up to "stock" and was driving it to a buddy's house, who has some test equipment. The GEN was on, voltmeter reading 0. About halfway there, I was at a stop light, chillin', when the GEN light went out, and the voltmeter jumped up to about 14 Volts. Got to his house, and everything was working fine, charging perfect.
So my only guess is there is a loose wire, or the circuit board has issues. I have a feeling this won't be the last I see of this Gremlin.
Here is the latest. As I said, I got it to work with a "Temporary" GEN light and wire. I hooked back up to "stock" and was driving it to a buddy's house, who has some test equipment. The GEN was on, voltmeter reading 0. About halfway there, I was at a stop light, chillin', when the GEN light went out, and the voltmeter jumped up to about 14 Volts. Got to his house, and everything was working fine, charging perfect.
So my only guess is there is a loose wire, or the circuit board has issues. I have a feeling this won't be the last I see of this Gremlin.
