02 Dual Alternator Problem

bad12jr

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Hey guys,

Having a weird problem on the SD. Has the dual alternator setup from the factory. Had a charging issue about 3 weeks ago. Had remanufactured alternators which I in the past have had horrible luck with. So i remove them and take them to a local rebuilder who had always done great work for us. Well now it appears that the upper alternator or both have quit?

Does anyone have a schematic or test procedure for the dual setup. Checking the wiring in the harness appears good. The harness on the upper is reading 10.8 v DC on one pin and .143 v AC or so on the other pin. Need to check the lower but need a longer set of test leads for my meter so as to not get burnt.

Will the dual setup turn on the lower alternator if the upper quits? Just checked the system last night as I have everyweek till I get a voltmeter for the cab in just to keep an eye on it. It was putting out 13.6 volts and everything was fine.

Only aux power draw is a 800 watt kenwood amp hooked to two 8'' subs and the headlights are wired through relays with just the switch turning the relay on.

I'm out of ideas at the moment. Without a schematic I'm at a standstill. Done a good bit of electrical troubleshooting in college and while working on small engines so nothing new.

Sorry for the long post but appreciate the help. Thanks
 

PDT1081

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Does the battery light come on? Only experience I have with dual alternators is my uncle's truck. His water pump started leaking and dripping onto the lower alternator. It went out and turned the battery light on.
 

bad12jr

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It was. I believe I found the problem. Went and talked to the alternator guy and he said he'd check it over. So come to find out the grounds are in horrible shape and was getting and loosing ground intermittently. He just happened to bump the wire while testing things and found it.

Sent from my x2 somewhere
 

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