battery light

[legalize420]

if you disconnect the alternator plug should the battery light come on? im trying to figure out why my alternator is not charging. only seeing 12.1 volts. battery light is not on. alternator and battery test good. all power and ground wires were upgraded to 2 AWG cable. i also installed a new alternator plug from fordfuelinjection so im only running the green/red wire. the yellow/white wire is connected to the post on the alternator. i checked fuse #18 and its good. im thinking it might have something to do with the green/red wire that goes to the dash. maybe the bulb and resistor burnt out . if that were the case would the alternator not turn on?

 

[legalize420]

ok well the bulb is definetly out. when i turn the key to the run position the light does not come on.

 

[Zero_chance]

That doesnt mean the bulb is out. That circuit is completed through the alternator. When they go out, the battery light doesnt necessarily come on. Trust me on that one. My first one died and I only had the stock gauge to go by. Got back to my dealership and tested it, output was 12.9V. Light was off. I thought the same thing about the bulb as it never proved out. Replaced the alternator, light proved out normally. Then my second one went at the Fun Ford Weekend in NH. Same thing, no light on, only this time I had Autometer gauges to clue me that I wasnt charging. Light was off the whole time.

Id say the most likely suspect, assuming your rewiring is correct, is that the alternator is bad. Bring it to a store and get it tested to know for certain. If your wiring is up to snuff, then thats more than likely where the problem lies.

 

[legalize420]

section 13 of the troubleshooting in the haynes manual says "alternator light fails to come on when key is turned on". mine does not light up when you first turn the key. i had the alternator tested and it passed. everything is wired correct. the problem has to be behind the new part of my green/red wire. there is a connecter near the underhood fuse box with the green/red, white/yellow, and two other wires that go to the a/c compressor. that is where i cut and soldered in the new wire. from that point back to the dash its stock wiring.

 

[Zero_chance]

Yeah if the alternator tests good and the fuse is good, its more than likely a wiring issue. Id post up some better wiring diagrams directly from the Ford OASIS site but I changed my password last week and now cant log back in because I forgot it . Id very carefully go over any of the alterations you made and double check them, if not returning them to stock if need be. Good luck.

 

[HISSIN50]

The stock excite circuit uses a 500 ohm resistor in parallel with the bulb just in case the bulb burns out.

Check for voltage at the excite wire on your regulator. YOu should see one to several volts.

The battery light will not illuminate if you unplug the regulator plug. The reg is what grounds the light.


Be sure you didnt blow the fuse for the new charge cable, and that all charge cable connections are solid.

Good luck.

 

[legalize420]

i just went out and checked and i am getting voltage at the alternator plug with the key on. green/red and yellow/white both have 12v. so i guess it has to be the alternator. when i had it tested it passed. is it possible for it to pass with a bad regulator?

 

[legalize420]

fixed. i guess it was the regulator. i went back to the parts store and exchanged the alternator for another and everything is good to go.