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Old 05-27-2010, 01:25 AM
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Originally Posted by davidvend View Post
...also please note everything is grounded and grounded again...
You're the MAN! It tickles me when you guys troubleshoot and fix your problems using sound troubleshooting techniques. They work.

Your GEN light is fed from both ends with +12. The key switch feeds it, and so does a running generator OR alternator. (That's what turns it off.)

Some folks call it a 'TEST' light, because it shines when the key is on but the engine is not yet running. Originally (during generator days) it was connected to the armature (A - on the regulator), automatically polarizing it with a small current from the bulb. This is important because if the bulb is burned out, a generator may not charge.

The deal is, there is a relationship between the battery, the armature, and the bulb. The bulb only shines when the armature is putting out less voltage than the battery has.

Bulb shines when you:
Throw a belt, and the gen puts out less than the battery voltage;
Turn the key from OFF to ON, and the gen puts out less than the battery voltage.

Alternators God love them... They're always connected to the battery and depend on good diodes or they would drain the batt in no time. Alternators don't know when the key is on, so they use a 'SENSE' wire. Yep, you guessed it... the GEN light wire is tied to the key switch. So, how much voltage should the alt put out? The 'sense' wire tells the voltage regulator how much voltage is on the key switch, and the alt will produce power until 13.5-VDC is sensed on that wire.

CAUTION: If you have weak or loose wires feeding your dash, the alternator could produce more than the battery will take. Good grounds are JUST as important.

Dave, troubleshoot your GEN light from the yellow/blk wire. If you ground the wire (with the key on but the engine stopped) the light should shine.

If it doesn't shine, your troubles are from the key switch to the light socket, through the bulb, and out the firewall. The bulb is NOT grounded to the dash.

If it does shine when grounded, the problem is in the regulator connection (be sure the regulator has a good ground).

Follow this instruction and let me know what you found. Adding a 'shunt' resistor around the GEN light will make the bulb even dimmer, so tackle that later. - Dave

EDIT: There are no fuses on your ignition circuit. A yellow wire comes from your starter solenoid (+B), connects to your headlight switch (B), and jumps over to your key switch (B). From the key switch (IGN), a black/green wire feeds your bulb. The other bulb wire (yellow/black) continues through the firewall, to your voltage regulator.
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Last edited by simplyconnected : 05-27-2010 at 02:07 AM.
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