Alt. light stays on....
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From: Boise, ID
Alt. light stays on....
I'm having an issue with my alternator light with the truck in my sig. It stays lit constantly. First I figured the alt. was bad so I took it off and had it tested. It checked out OK. I then took the truck to a parts house and had the charging system tested. Everything checked out with 13.4 volt output at idle and 51 amp output around 2K RPM so the battery is getting juice.
The battery is new but I can't vouch for the electrical system in the truck. I've ran the wiring diagram and everything matches under the hood. I'm not sure about under the dash. A PO had done a pretty good hack job with adding a voltmeter and ammeter but I pulled all that and returned everything to what I believe to be stock.
Can anyone give me some pointers? I don't want to just pull the bulb. I prefer not to band-aid. I don't know how long this problem has been going on. I've had the truck for a over a year but just got it running 3 days ago.
The battery is new but I can't vouch for the electrical system in the truck. I've ran the wiring diagram and everything matches under the hood. I'm not sure about under the dash. A PO had done a pretty good hack job with adding a voltmeter and ammeter but I pulled all that and returned everything to what I believe to be stock.
Can anyone give me some pointers? I don't want to just pull the bulb. I prefer not to band-aid. I don't know how long this problem has been going on. I've had the truck for a over a year but just got it running 3 days ago.
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Joined: Jan 2001
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From: Virginia
Alt. light stays on....
Try replacing the regulator. This is what controls the light. If this doesn't fix it, then you must have a few wires that are still not right.
Here's a diagram of how it's hooked up. Basically the regulator grounds the light to make it come on. When the alt is charging, the regulator is supposed to recognize this, and takes the ground off the light, making it go out. There is also the possibilty you have a miss-match wiring for the type of alt system you have. If you have it wired for an amp guage system, then the alt light will not work correctly.
This is the diagram for an idiot dash light system.
Here's a diagram of how it's hooked up. Basically the regulator grounds the light to make it come on. When the alt is charging, the regulator is supposed to recognize this, and takes the ground off the light, making it go out. There is also the possibilty you have a miss-match wiring for the type of alt system you have. If you have it wired for an amp guage system, then the alt light will not work correctly.
This is the diagram for an idiot dash light system.
Last edited by Franklin2; Jul 7, 2003 at 12:05 AM.
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Elder User
Joined: Feb 2003
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From: Boise, ID
Alt. light stays on....
I was afraid someone would say that. I just might have to give that a try.
The amp gauge I referred to was an aftermarket unit. In the pic below you can get an idea of how it was wired up. The two heavy blue wires were running inside to the ammeter. I removed the second solenoid, pulled the wires, and moved the main power supply wire back over where it should be. Are you saying there might be some other modifications in the wiring I haven't seen to make that old setup work?
This is what it looks like now.
I really appreciate the diagram!!
The amp gauge I referred to was an aftermarket unit. In the pic below you can get an idea of how it was wired up. The two heavy blue wires were running inside to the ammeter. I removed the second solenoid, pulled the wires, and moved the main power supply wire back over where it should be. Are you saying there might be some other modifications in the wiring I haven't seen to make that old setup work?
This is what it looks like now.
I really appreciate the diagram!!
Last edited by 77'F-150Mudder; Jul 7, 2003 at 12:24 AM.
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