Things are getting fun in here! Thanks guys for all the advice. I just replaced the alternator - and it's not really making any power. Knowing that the PCM doesn't command it to turn on until after the GPR relay turns off is a great nugget of info to have.
To be clear - the fuse that is blowing is fuse #9 in the battery junction box, not under the dash.
I did disconnect the fuel bowl heater before the two fuses blew, but I haven't opened up the harness as of yet - but when checking with a DMM - it's showing a short to ground even without the keys in the ignition. Now that I think about it... the wiring diagram shows that until it gets to the relay, nothing should be getting power with key off - so that helps narrow down locations for shorts.
I've attached an image of the wiring diagram to the fuse that's blowing. I triple checked the routing of the wires in the wiring diagram and am certain that's where the diagram says the circuit connects to.

 

OK, so there were two fuse panels and junction boxes pictured in the Ford Service Manual, looks like I lost on the 50/50 guess...

Below is an image of the battery junction box that may be more in line with your van.





You said fuse position 9 is the one blowing out, which according to the image above is labeled as "PCM Power Relay" and "Battery junction box fuse 4". Can you verify this with what you are seeing in/on the van?

Based on your diagram you posted with the red box identification of parts. I would suggest checking that relay to see if it is faulty. Easy and quick check that may be the issue. I had a relay go bad on one of my vehicles that would turn the AC on whenever it felt like.

If that doesn't work, go to the next easy targets by disconnecting the GPR and AIH relay and insulating the hot side of those harness connections. See if you still have a fuse blowing out condition or see if you still have power to the fuel heater connector. This will get us started on the process of elimination to find the source of the short.

Keep us updated!

 

I've managed to get the short isolated to something downstream of this connector:

connector that goes to injectors/GPR/IPR

However I cannot find the pinout for this connector - so all I know is that the short is somewhere in this harness - but no idea where in this harness. Does someone have a pinout/wiring diagram for this connector? Also - considering I have alldata and mitchell diy (neither of which have this info) where can I get this sort of critical information?

 

If you are referring to the 42 pin connector over the valve cover that someone's hand is on, see if this does something for you. They are for the 2000 Econoline 7.3L diesel. Verify the wire color codes before proceeding as there were minor changes between the Super Duty years and I cannot say for certainty this diagram is 100% correct. It should be though...

 

I just realized this gives you the circuit ID and the color code, but not the circuit designation... The connector number is C166, let me do some more digging to see which circuits are for the GPR, AIH and other circuits that you ID'd in post #16.

 

GPR is circuit 16, pin 35 and is RD/LG.

 

I am having trouble identifying the AIH as it does not appear to be identified as Air Intake Heater in the manual. Still looking... EDIT: found it under Manifold Intake Air Heater (MIAH)

Using the process of elimination to our advantage, I have pasted two links from the 7.3L PSD Tech Folder that may help.

• IDM - 42 Pin - UVCH Map
• 42 Pin Connector Map

 

That's the connector for sure! How did you get this diagram? I couldn't find it in my resources - but now I need to trace from the wire colors to the circuits since "CIRCUIT 555" doesn't mean anything to me. I'm starting to wonder if I should just pull that half of the harness out and go through it on a table and fix any chaffing etc. If the wire colors match - I can peel back the harness loom around the connectors and see what color the wires are and trace it back to this diagram though. It's a good next step, thanks!

 

MIAH is circuit 462 and 3996 on pins 26 and 32.

Pin 32 (3996) lines up with the color as being RD/YE, but pin 26 indicates VT on the diagram and PK on the connector map. Need to verify this with a continuity test before searching for a fault.

 

I went to IDM in the "components" section and identified C166 as the 42 pin connector. Then I went to connectors in that diagram and found the male and female pinout map. Then, I went to GPR and MIAH component section and looked through the diagrams until I found the circuits that match the 42 pin connector map.

It is rather tedious, but it works...

Speaking of that, have you looked at the wires on the underside of the connector that cross over the valve cover. This is a common friction point that many of us have reinforced.

 

I am not sure what AllData looks like, but this is what the FSM looks like. See the different volumes/sections and the sub-sections?

At this point, I will let you be the eyes and hands for a bit and keep tabs on your progress and help out in anyway I can. If you find yourself scratching your head, just come back to us and tell us what you see.

 

@Mikethezipper , you had any time to look further into finding the gremlin in your electrical system?

I am hopeful you figured it out and have been too busy enjoying life to come back for an update.

 

Unfortunately I've been fighting gremlins most of this time. I think I have two intermittent shorts that hop around just to spite me. I pulled the main engine wiring harness and I'm replacing any chaffed or exposed wiring as well as some plugs that have disintegrated over time. At some point it was looking like I was getting an intermittent short from the IPR circuit and also from the PCM (no short when disconnected). I'm just taking it slow and methodical. After blowing too many $5 maxi fuses I am switching to resettable breakers that come in the same form factor. No real progress z just slowly plodding along. Thanks for checking in Sous, always nice to know I've got someone rooting for me!

 

Good idea on the breaker. Sounds like you are doing what needs to be done.

Let us know if we can be of help going forward.

 

I spent forever fixing all the little issues with the wiring harness. I replaced 3 ugly connectors and patched some bad sections of cables. There didn't appear to be any broken wires or chaffe in areas that could short - but I got it put back together and the van is running again. Now I'm back to figuring out how to fix all of the other issues the van has Thank you all for your support! I'll look at getting one of those DVD service manuals - although I don't have a dvd drive anymore I'll see what I can do.