Like the title says fellas, driving home the other day on the expressway the truck dies, I pull over, pop the hood, and sure enough the shutoff solenoid is down with the key in the "ON" position, I wire tie it up to get back home and replace it, but as soon as I start it up I notice my tach isn't working. I start moving, and my speedo isn't working either!

I get it home, and its dark, so today I am sitting in the shop trying to figure out whats wrong. I know the alternator isn't charging anything, and it has 0v at the field terminals, but the positive field terminal does have continuity with the PCM pin it relates to. I haven't checked the ground wire, but I can't seem to find where it taps into the PCM.

I have checked all of the fuses, nothing looks to be shot. I swapped a few relays, and everything is the same.

Anyone have any better ideas? Anyone around have a 97 12V stick shift they want to let me try swapping the PCM out of? I pulled the 98's out thinking it would work, but I was informed they are not swappable.

I'm ready to blow a fuse myself!

---AutoMerged DoublePost---

Forget it...I'm an idiot.

I looked at the fuse panel at least 2 times, thinking that IF a fuse was blown it would have melted or at least blackened up.

Well I went through, pulled each fuse individually, and pulled a 10amp fuse out that had a crack in the wiring, shined a light behind it and it is all the way through. Put the DMM on it to see if it has continuity between the pins and nothing. Popped a new fuse in and everything seems to work fine.

 

Glad you got it fixed!!! You can close this thread yourself by going Under Thread Tools and clicking Close... If not I'm sure a Mod will be by soon!

 

Well, I thought I had it fixed...

I went out to start the truck (before I just turned the key to "on" to see if the WTS or WIF light came on, and when they did I figured it was fixed), and when I cranked it it blew the fuse again, this time a 15amp, which replaced a 10amp (its all I had laying around).

Where can this be shorting that it would blow a 15amp fuse...do I dare use a 20amp? I don't think its a good idea, but my buddy figures why not, I'm thinking the trucks gonna burn down if I do.

 

you got a dead short somewhere if you put power to it and it kills it and YES, you are asking to burn something up.......

 

Time to get out a GOOD volt Meter and start chasing down shorts... Have fun!!!

 

Yeah, I have a nice Fluke DMM and so far I haven't been able to find crap...not that thats what I was looking for in the first place, but you get what I mean.

It turns out this #9 fuse powers a lot: AC compressor clutch relay, fuel pump relay (not on a 12V I would think), Automatic shutdown relay (again, probably not in a 12V), PCM, Shutdown solenoid relay, Intake heater relays 1 & 2, Diagnostic plug and the Fuel heater relay. Anyone know there the fuel heater relay is?

I pulled the Shutoff solenoid relays, and the entire PCM, and its still shorting, but only when I crank the starter...I haven't tried yet, but I'm gonna pull the fuse, start the truck, and put a fuse in after its started, if it pops I know its not something in the starting sequence, if not I have a lot less to track down I think. What do you all suggest now?

NEW: Alright, I have pulled every fuse in the PDC, the PCM plugs, the F/S solenoid, heater grid solenoids, fuel heater solenoids, EVERYTHING! and I still get an instant blown fuse when I turn the key to the "ON" position. So that would definitely indicate a short in the wiring correct? I'm not missing anything? Just double checking here guys...

I need another set of hands to come help me with this damn thing.

 

Start Unplugging things in that circuit one at a time , and see when the fuse stops blowing ( a circuit breaker can be handy here , or you may need an entire package of fuses)

When the fuse stops blowing , you just found the problem ( IE - unplug the fuel heater , and the fuse does not blow when the key is turned on, this means there is probably a short in the fuel heater)

Alternatively , you can check everything in that circuit with the fluke meter , but you will need a complete vehicle wiring diagram/pinout diagram , in order to know what should and should not have continuity, and continuity to ground.

 

I found the plug...its the F/S solenoid harness, but the upper plug, not the one plugged directly into the solenoid. There is another plug farther up the harness, and there is another set of wires that crosses it and looks to connect, I haven't had time to deal with it, I just unplugged it and have been running like that, well, that is until today when I seized the NV4500, not a great track record with this truck so far...within 3 months the electrical has blown up, the head gasket has popped 3 times, and now the tranny goes. F'ing A Cotton!

 

Do you have an update on this?

 

Yeah I got it figured out. It was a chaffed wire to the A/C Compressor clutch, my guess is when Cummins NE fixed the head gasket, they rubbed the wiring there (since ts close to the head)...A new piece of 16 gauge and it works like a charm now.