2.3L ('83-'97) 94 Ford ranger (2.3) new alternator not working, battery light on

[mjricha]

94 Ford ranger (2.3) new alternator not working, battery light on

So I've replaced the alternator and battery twice. They're both new (both times) and have both been benched tested at auto zone and test good. Battery reads 13v, but steadily drops while the truck is running.

The wires are in good condition. I have tested the battery to alternator bolt wire (black and orange). Get battery voltage across. I've tested the yellow wire at the alternator harness and get battery voltage. I get continuity from the body of the alternator to the frame, and from the frame to the battery. The battery light is on in the truck when it's started. Is there anything else I can check? There's a single white and black wire that connects to the alternator on its own, and it's not brittle or anything. All fuses have been checked. If anyone can give me any advice id really appreciate it.

 

[SenorNoob]

There should be a wire that only has power when the key is on. Is that working?

 

[mjricha]

Nope, no power on the green wire with key on. I ran a 12v acc wire and jumped it to the alternator and now it seems to be charging, but only at about 13.75 volts and not 14.5 like normal. I tested the green wire for voltage at several points in the line and got nothing. Running the 12v jumper to the green wire itself blew the ignition fuse. I've looked through the cab and traced the wire as much as a could and can't find any points where its broken or frayed like it would be shorting out.

 

[SenorNoob]

Interesting, isn't voltage supposed to vary with battery state? I've never really looked into how that would work tho.

 

[oldgeek]

There's a fuse in the relay box by the battery. 15A if I remember right. No charging if it is blown.