Have you unplugged the fuel heater? Please don't just say its not the problem please PLEASE just unplug it.

Perhaps you already did say but what color wire are you dealing with that is grounded? Where is it located?

For diagrams click the picture in my signature and go to the wiring diagram album. Might be able to see them close enough. I have to send these file via email to a bunch of people so PM me your email addy and I will send them out to you.

 

Simple diagram, but accurate ...

Battery -> Ignition switch -> Fuse 22 -> TO: fuel heater, glow plug relay, pcm power relay

Unplug fuel heater and recheck.
Disconnect glow plug relay and recheck (small wires).
Unplug PCM relay and recheck.

 

Also check the power diode.(direction)
The bone heads could have installed it wrong.

Bill

 

okay... ITS NOT THE FUEL HEATER!

its not my first day wrenching or tracking wiring.


there it is, so there is no doubt. the wire that is grounded is red with a green stripe. it gives a full 12.0+ volts between the r/g wire and the positive battery terminal, and has continuity with the negative terminal in both off and start. the red and green wire provides power for TO maxi-fuse 22 in the distro box under the hood, goes through the firewall, and to the ignition switch box located under the steering column where it terminates. it branches at some point and provides power to the in dash fuse box for the fuse for the gauges, fuse 17.

i was checking voltage using every setting i could think of. with fuse 17 in place the r/g wire was grounded regardless of the position of the key. with fuse 17 pulled, the wire was neutral (neither hot nor common ground) with the ignition off, and had a reading of 8 volts between the r/g wire and the positive terminal with the ignition on.

according to the wiring diagram at autozone.com, this wire goes to the dash then to the generator (??). so thats where i'm at now.

as far as i can tell, the wire providing power to the r/g wire is bad (fusible link somewhere), and something powered by fuse 17 is bad and grounding the circuit.



I've been using the wiring diagram at autozone.com for reference purposes.

the link is

AutoZone.com | Membership Benefits

if anyone sees a problem with this diagram please say something, as this is my reference document for now

 

Pic is clear as mud .. All 12 v sources connected to the fuel bowl ,come from fuse 22 . P side of the fuel bowl is the main connector.. Did you dis connect the heater yet? & re connect the cut wiring?...

 

.......x2...... Guess he does not believe us ...

 

Picture show the unplugged Fuel Heater.

Thank you Navy for showing that. I am sorry I was insistent that it was unplugged. I just don't want to waste time diagnosing a common problem with complicated diagnostics.....

I will be back later to brain storm...

 

The fuel heater may be unplugged , but all the other wiring is still intact, is the main plugged in(to the IPR)did he repair the wiring yet ?...................................

 

the small silver dot about the center of the picture is the spade connector for the fuel heater. the wiring for fuse 22 has been repaired and the distribution box reattached.

the fuel heater is disconnected.

I tried starting with the multipack connector that is on the passenger side of the fuel bowl connected and disconnected, and it made no difference

the fuel heater is disconnected.

I do believe you, but that is not what the problem is. the problem is that the wire that provides power to fuse 22 is not being energized when the key is turned to the start position, and for some reason the wire is being grounded when the fuse 17 in the in dash fuse box is inserted.

so, in recap: the fuel heater is disconnected, the red/green stripe wire is not being energized to provide power to fuse 22 in the under hood distribution box, something in the circuit protected by fuse 17 in the in dash fuse box is grounding the circuit, and the fuel heater is disconnected.

 

yes i repaired the cut wiring. wiring was stripped back, soldered, and heat shrink tubing was applied to protect the wiring.




Its cool, i understand, between working on the truck, and trying to convince everyone it was indeed unplugged , i was getting frustrated. I'm still working schematics, and its dark out now, so i'll be working on it again tomorrow.

Right now i'm thinking tracing the wire that should be energizing the r/g may show why the circuit isn't being energized. i'm guessing fusible link or melted wire.

 

Navy I am not sure what the AZ diagrams look like cause I couldn't open them. If you would like I have about 8 emails I can send you which will give you every system diagram straight from Mitchel On Demand which I use at work. They are great quality. Might help might not...PM me your email address if you want them.

 

OK Fuse 22 is powered from the Ign switch like you know through the red/lt grn wire. The ign switch provides power to the R/g wire in start and run positions and the power comes into the switch from the yellow wire. The yellow wire is powered by the 50 amp fuse in the #17 position.

 

I think we are making progress.
Fuse #17 (10A) in driver compartment controls the following ...

1. Diesel warning lamps.
2. Warning chime module.
3. Transmission control switch.
4. Instrument cluster.
5. Fuel in water switch.
6. Low vacuum warning switch.

Hot side of fuse #17 is Red/Lt Grn.
Above component side of fuse #17 is Red/Yel.

Hot side of fuse #17 driver compartment and fuse #22 engine compartment are tied together. They are both protected by fuse #17 50A engine compartment.

 

I re read the thread & I don't see where the wiring to the IPR was checked . Its common for them to short out there

Have we verified the PCM sending ground to GPR ?

Also ., there are 4 relays in the distribution box .. You can use #4 as a test . move it to pos #1. Realy pos# 3 is the horn ,you can use that position to test all the relays . Also test # 9 fuse pos , it is also for PCM..Is the CEL coming on (key on ) , faintly?....

 

I think the clue is in the statement above highlighted in blue. What threw me was there are 2 fuse #17's. One in the engine compartment and one in the cab.