Alternator Questions

Over the weekend I was doing a water pump on my M1009. Everything was going great until I was using a rubber mallet to help break free a frozen bolt near the alternator. All of a sudden I got a short on the passenger side alternator (I didn't disconnect the batteries), the short ran down the power wire, to the 12V junction box were it burned itself out (I think).

My question is what are some thoughts about what happened and what damage was done? I had been getting a intermittent GEN1 light before this. I haven't had time to put everything back together to start tackling the problem, just hoping for some ideas about where to start.

Thanks

The "Ground" terminal on the passenger alt is fed by the 12v wire coming from the 12v terminal block. This is how the 24v is generated.

This ground post and wire needs the rubber boot to cover the leads. It sounds like the boot is possibly missing and when you hit the bracket, the terminal shorted out. This is a direct short thru the wire.

More that likely just the wire fried. There is a fusable link in the wire at the 12v terminal block. You should be able to just replace this link. It is the red dashed line on the attached diagram. The fusable link is 12 gauge and the red wire is 8ga.

Since you where having a Gen! issue already I would pull both alts and have them checked at you local parts house. Just tell them to connect the ground lead to the ground terminal instead of the case.


Right click on the thumbnail and choose "Open Link in New Window"

Thanks for the help. It was just those wires and my vehicle is up and running.

Glad you got it fixed. What caused the short? Was it the ground terminal shorting on the bracket?

Yup it was exactly was you said it was. The rubber boot dry rotted off and while I was moving the alternator it made contact the motor. The 8 gauge wire survived just the 10 gauge at the junction box burned.