Any idea as to where the electrical system could be shorting out to blow a 15amp fuse where a 10amp should be (its all I had left)? Again this is for the Shutoff solenoid and PCM power fuse. It sounds like a simple problem, but I figured maybe someone has run into it before and had a simple fix. I don't want to tear apart all of my wiring just to find that a harness cracked or something stupid like that.

Any ideas where I should start would also help. Thanks.

I pulled the shutoff relays and the shutoff itself but to no avail. Its still blowing that same fuse. Where does the line run after it leaves the fuse block...in other words, WHERE could it have shorted out?

 

Ok,

with the fuse out

Use your volt meter and check the direction that the juice flows through that fuse. One side will have the 12V with the ignition on while the other should be zero.

Once you have found the "hot" side, Check the opposite side for continuity to ground. Then check it with the shut-off solenoid unpluged.

If you have a meter with an audio signal for continuity, you can start wiggling the wires around till you hear it breaking up; or you can have someone watch the needle while you wiggle wires.

Bet you have a wire chaffed through to the frame.

 

Alright Timmy, I did what you said and found that the top plug is reading that it has continuity with the ground, but with a resistance around 50-100 ohms.

I take it this should not be?

At this point, as soon as I turn the key to the "ON" position it blows the fuse. I have every relay of the PDC pulled, the F/S pulled, and the heater grid relays pulled. Even the PCM plugs are pulled...as far as I can tell that is everything on the fuse (should be with all the PDC relay's pulled).

Should I start pulling apart the harness to see if I can find a chafe?

 

A resistance of 50 ohms would mean a total current of about 1/4 amp which shouldn't be enough to blow the fuse. However, if it is a chafed wire, since it is a poor connection, it could spike the current high enough to blow the fuse.

Unfortunately, I don't really see anything else to look at other than the wiring harness. I think that you have successfully unplugged everything that you can.

Good luck.

 

one side should have a resistance with it bieng a grounded system. with the fuse pulled and the key on one side of the fuse holder should have 12v and the other should have no voltage but resistance to ground. as far as the 50-100 ohms is that with the shutdown solenoid pluged in or unpluged. im wondering if it is controll power for the relay or the power for the solenoid. also i saw a schematic for this once and i think that the fuel preheater is in series with the shutdown solenoid.

 

Are you getting resistance with the Fuel Shutoff solenoid itself unpluged?

 

I am getting resistance with EVERYTHING unplugged, this is what boggled me. With nothing plugged in everything should be a dead end, which should mean no continuity I would think. I have pulled the prehaeter, the gird heaters, the shutodown solenoid, the PCM, the AC clutch relay, every relay in the PDC basically and still it pops without hesitation.

I did have it once when the voltage was low enough where the truck started up, ran for 3-4 seconds then it popped, what that means I don't know, but it must mean something. I gotta work today, but I'm gonna look at the truck again tonight and try to get a buddy to come help me with it.

 

http://www.fostertruck.com/images/Ram_wire_diagram.jpg. I got this off a nother post hope it helps. it looks like the fuse in question powers the coils for most of the relays involved with starting the truck, not actually the power to the solenoids or heaters.

 

Thanks Sparkey,

Is that a generic diagram for a Ram or specifically for the Diesel? I only ask because I don't know what an auto shutdown relay is.

Also, what is the trans relay in the PDC for...I have a stick, why would I have any electronics in the trans?

 

Seeing that it has the grid heater system and shutdown solenoid it must be for a diesel.

 

not sure if all the relays apply but the trans relay might be one of the plug in in the transfer case. probaly a relay for the 4x4 vac switch

 

Infidel,

If it was generic it would have all of the possible wiring, so a gassers, a diesels, V8, V6...everything lopped onto of it. I had a similar diagram, but it was missing a few of the items on that diagram, thats why I asked.

I found the plug the short is coming from. It is in the shutoff solenoid...but the upper plug in the line...which I never thought to unplug, I just unplugged the one closest to the shutoff solenoid itself.

Well between those two plugs is another wire that crosses through it. It looks like it goes to the A/C compressor, so I unplugged the A/C clutch and it still shorts out. Now i gotta pull the wires apart and check those. At least I have my alternator and speedometer back now.

 

Just curious.....Where do your instrument cluster gauge needles point when all this is going on with your truck ??

I ask this because I'm have a similar issue with my 98 12 Valver. Although, mine isn't popping any fuses (that I know of).

Mine "may" be a bad voltage regulator inside the PCM. Too cold outside to get it checked out.