I've got some manuals in and am reading them, I promise. Also did a search. TOO many results...My Gen 1 light doesn't work. I tried swapping bulbs with Gen 2, which works, same results. Gen 1 is working, I've got 14 volts at battery, just no dash light when key is turned to run position. Any idea where to start looking?
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No Gen 1 Dash Light
- Thread starter renovate7
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Barrman
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Did you pull the gauge cluster to swap the bulbs or just reach up to do it? The big plug on the back of the cluster, the copper leads on the cluster, the ends that have to be clean, the holder, the contacts on the holder and the bulb all could have an effect on if it lights up or not. Plus the whole why is the alternator working when the light isn't thing?
I would suggest pulling the gauge cluster and pulling every bulb holder off. Clean with a scuff pad or small file all light contacts, the holders and check with a 12V source every single light is working. Then, put the bulbs back in and verify they light up from the contacts at the big plug input. Plug the cluster back in and see if it works then. If not, follow the big and small brown wires which are the Gen 1 + and -.
I would suggest pulling the gauge cluster and pulling every bulb holder off. Clean with a scuff pad or small file all light contacts, the holders and check with a 12V source every single light is working. Then, put the bulbs back in and verify they light up from the contacts at the big plug input. Plug the cluster back in and see if it works then. If not, follow the big and small brown wires which are the Gen 1 + and -.
Thanks for the reply. I just reached up and changed the bulbs. I just got this 1008 and am working my way thru it. I'll pull the cluster and clean and track the wires. Gen 1 is definitely working...Gen 2 light was on and Gen 2 not working when I got this. I did a light pressure clean of the engine compartment and pulled the plug from Gen 2 to check voltages. Plugged it back in, and Gen 2 is now working. Don't know if it was plug or relay sticking. I think this truck sat for a long time before I got it. It's "fun" bringing it back to life.
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There is a nice compilation of "Sticky" threads and the wiki in the CUCV forum. Many deal with electrical. Try reviewing some of these as well. May be able to shed some light on problems you don't have yet.
What Turns Gen 1 Light On?
I've traced all my electrical Gremlins, installed a lot of new bulbs and relays, and have everything working except Gen 1 light. It doesn't come on with the key in the run position, engine off. I've swapped the bulb with a known good bulb. Wiring diagram F-9 shows a wire straight from the generator to the light with no diodes/relays/fusible links. With the key in the run position, engine off, the bulb is supposed to be on. With the engine on, generator working, the bulb should be off. What "switches" to turn the bulb on and off?
I've traced all my electrical Gremlins, installed a lot of new bulbs and relays, and have everything working except Gen 1 light. It doesn't come on with the key in the run position, engine off. I've swapped the bulb with a known good bulb. Wiring diagram F-9 shows a wire straight from the generator to the light with no diodes/relays/fusible links. With the key in the run position, engine off, the bulb is supposed to be on. With the engine on, generator working, the bulb should be off. What "switches" to turn the bulb on and off?
It is a straight shot, but it does go thru the firewall plug which is known to cause issues. The terminals have a black goo on them that cause contact issues.
The internal components of the alternator "turn on an off" the exciter circuit. You can find a copy of the GM manual for the alternators. They get a little technical.
The internal components of the alternator "turn on an off" the exciter circuit. You can find a copy of the GM manual for the alternators. They get a little technical.
So...I went out and did some more troubleshooting. I used a test light and have power to one side of the socket the bulb goes into on the back of the dash. There is always power here, with the key on engine not running, and key on engine running. The "switch" that turns the bulb on and off must be on the outbound or ground side of this socket, and is always off, the bulb doesn't come on. This ground side goes back to the main plug that connects to the dash. Any ideas where it goes from there? Any ideas what changes to turn the bulb on and off? All other dash lights, turn signals etc. work.