M1008 fuse box problem

[trooper632]

Newly acquired M1008 has a problem, it is blowing the fuse for the charging system in the fuse box. Its the bottom fuse marked 28V, I have tried fuses from 10amp to 30 amp, keeps blowing them as soon as the key is turned on. Truck starts and runs perfect but the volt gauge doesn't work, that fuse runs the charging system. I don't see any of the fusable links blown anywhere and I removed the fuse box because the place where the fuse goes looks burnt but after looking at it I don't see that it would cause any problems, but im at a loss, any suggestions?

 

[Warthog]

You have a dead short somewhere.

The fuse controls the 24v voltmeter (controlled by the Voltmeter relay) and the GEN2 exciter circuit (controlled by the GEN2 relay).

Test the following

Remove the two pin exciter plug from the passenger alternator, remove the mounting plate that has the starter relay, GEN2 relay and the Voltmeter relay from under the dash (you may want to disconnect the batteries first). Remove the two smaller relays.

Install a new fuse and see if it still blows. If not the install the the GEN2 relay, check fuse, install the Voltmeter relay, check fuse and the install the exciter plug.

This should help narrow down where the short is.

I'm guessing that you alternator is shot.

While you have the relay mount bracket out, it is s great time to do the Doghead relay upgrade if it hasn't already been done.

 

[trooper632]

Well followed the instructions and the fuse blew when I put the rely in (closest to the starter relay.) Took out relay put another fuse in and installed the other rely (farthest away from starter relay) leaving the first relay socket empty. Did not blow the fuse, Put the second relay back in and blew the fuse. I also tried switching the relay around and it didn't blow so I know both relays are good, I took out alt and installed a working alt from my 1009, and it still blows the fuse. I checked all the wires that I can see and all look good.

 

[Warthog]

Pull the dash plate and check the wiring for the voltmeter. The socket is hot at all times. If it is grounding out it will blow the fuse

 

[trooper632]

Warthog, You the man. Took out the volt gauge and I guess the army replaced the gauge and used a metal bracket to hold the gauge in instead of the plastic one, didn't have a plastic one but got it rigged up and it works great. Much thanks, Donny

 

[Warthog]

Glad I could help.