mystery short

[tshermankb]

howdy there, like many others my m1009's charging system has been giving me some trouble lately. Thought both my alternators were bad until i went through the wiring and found a bad connection on the gen1 bulb socket which got my drivers side alt working again. Still no luck with the passenger side alt though, seems a short is causing the 24v fuse at the very bottom of the fuse block to blow as soon as i turn the key. I have spent way too many hours looking over the wiring diagrams and testing connections in the truck, nothing is obviously wrong. The only thing i found that i figured might be it is that the black and pink wire leading of the gen 2 relay grounds to the frame, cant figure based on the wiring diagram if that should be the case? Anybody have any tips to finding a short, or had a similar problem?

 

[319]

Has it worked properly since you bought it? It may be a short in the wiring to the fuse block,
or some conductive crud inside the fuse block. Also check the relays and diode to be sure they're good.

 

[Warthog]

Wow those pictures look familar.......LOL

Let's see if we can figure it out.

The 24v fuse is hot all the time and feed from the 24v Positive Terminal Board.

It in turn feeds the Voltmeter/Relay and Gen2 Bulb/Relay and ultimately the Gen2 excitor circuit.

It the fuse keeps blowing when the key is on, there is a short in one of these circuits. The Starter Relay is also 24v but is not fused thru this fuse.


Start by pulling the 2 prong connector at the passenger alternator. Turn the key on and see what happens. It could be a short in the voltage regulator.

Also check for 24v at the RED wire and the BROWN wire with the key on. If there is 24v at each the the wiring harness should be good.

Leave the 2 prong plug unpluged

If the fuse still blows then remove the Gen2 and Voltmeter relays and see if the fuse still blows. If not the add one relay at a time and see what happens. There is also the Gen2 Diode that could be bad.

Let us know.......

 

[1stSarge]

I working on a write-up I’m going to call “one of everything” because everything I troubleshoot has something wrong with it….anyhow, one of the 27,000 things I found was this… the passenger alternator wires looked normal like in the first photo, but when I pulled them off to clean them, …wow would you look at that…the red wire was worn completely through and shorted on the case, and the large red with white stripe wire came off in my hands when I touched it. Wonder if this is why my GEN2 doesn’t work?…
Hmmm…just something to look for

Oh, by the way....Guess what? Why yes…. you are right.. The alternator is fried….. Warthog, done with that rebuild write-up yet?
I’m ordering parts.

 

[Warthog]

….. Warthog, done with that rebuild write-up yet?
I’m ordering parts.

I haven't had time to work on it.....It is just the TM rebuild instructions with my own wit and humor added in, along with pictures. The hold up is editing the pictures with captions.

It took longer to take the pictures than it did to rebuild the alternator....

 

[mr.travo]

No excuse Warthog! LOL!!! Just kidding man. Just be sure to post up when you