I've been working on my 91 intercooled truck since monday now and cannot figure this thing out. Its got a brand new regulator and alternator on it. I've unplugged the plug for the regulator and grounded the field wire like it says on the paper that came with it. And ive tried putting power to both the the little field wires coming off the back and it still wont excite it to charge. And i put a different ECM in it. I was told it blew a 175 amp fuse for the charging system thats in the harness but i cant find the damn thing. What the hell is wrong with this???????????

 

my regulator is on the fire wall on my 91.

 

Has the wire harness been melted?

 

It melted the hot.wire that goes directly to the battery off of it because it came loose. Other than that Monday when it messed up nothing else was hot other than the wire where it connects to the alternator to the little junction box where all the wires come together on the alternator.

 

Well mine melted or was melted when i bought it but theres a couple wires that melted that all had to do with the charging and after i rebuil the whole harness there was one wire that wasnt conected from the key hot at the ignition that kept it from charging

 

Check your fuseable links.

 

Thanks guys i'll check it out

 

I had the field wire between the alternator and PCM on my 93 break so you might want to test that one, I think it was pin#20 on the PCM but I could definitely be wrong on that.

 

I finally figured out what it was. the wireing harness for the alternator where the hot, gound and two field wires come together shorted out or something inside it.