Stop playing around and buy yourself new uvch. You've clearly diagnosed it being the passenger side uvch. The newer style have been upgraded so no more need for the 50 cent mod. As I've stated before they usually fail internally. When I replaced mine I cut them apart beyond being able to use them to find the bad spot inside just to satisfy my curiosity.

 

I just replaced both UVCH today with Motorcraft harnesses today. They came without new gasket/male connections, just the harness. That’s why I am thinking pigtail or potentially the gasket connection but I’m don’t think that’s it because it there was no wear on them at all.

 

How about checking continuity on the common wire on the passenger side? That's the center pin that flows the juice for all injectors on that side. From VC gasket to 42 pin connector (P+ below) then from 42 pin to IDM.

Useful PDF below.

 

Ok so I am going to try to do some ohm/continuity testing tonight if I can get a chance. I appreciate all these wiring diagrams with the numbers coded. Electrical is not my specialty and these really helped me understand and simplify things. A couple of questions for diagnosis and direction forward after I get my results:

• I did a buzz test again just to confirm all 8 were buzzing, they were, but the odd buzzes were noticeably weaker.
• So should I start my testing from the IDM connector that runs to the 42 pin connector, with everything connected from that harness to the injectors? My thought is that if my testing is good from that harness through the 42 pin, through the UVCH, through the injectors, then I don't need to test further, Correct? Or should I start at the the valve cover checking the injectors, then check continuity between the external VC harness tot he 42 pin, then to the IDM connection? Or does it not matter and is my preference?

For diagnosis:

• If my testing is good from IDM harness to the injectors, then I am expecting an IDM issue since the whole bank is being shut down?
• If I have issues with the testing, I should be able to identify the injector from the testing. If it is a short or something and causing the IDM to shut down the bank, then I should be able to remove the connector to the injector while its running and the other 3 in the bank should start firing, right?
  • Annnnnnd, if this is the case, and I identify 1 problem injector, I have seen the solenoids for replacement on them, can I just do that or is the whole injector poo poo? Are injector replacements just plug and play or is there more to the swap? ( I will go through videos, I just haven't yet). A full swap of the injectors is on my radar and I would certainly rather do them all (or most of them at one time) but for cost reasons, if I can buy some time until the end of the year before swapping all of them by taking care of this one now, then I'd rather do that.

Also, I checked continuity in all of wires on the UCVHs that I pulled off of the truck. Everything looked fine. Connectors looked good and not worn too. Do you think they are still good? This is why I am leaning a little toward the injector side of the UVCH and a bad solenoid on one of the injectors.

 

Ok so I ohm tested from the VC, 42 pin, and IDM connector and I got 3.8-3.9 across the board. IDM looks rough (externally anyway). I also did the other 2 tests in the pic below and all were good.




After checking the IDM connector, I plugged it back in and fired it up to see if it was a connection issue. Same running problem. I pulled the harness to the passenger VC while idling and there was no change in idle at all. So to me that tells me it’s getting no power.

I’ve read that when the IDM is putting itself into safety and shutting down a bank due to a short, the truck will usually start up normal and then the IDM shuts down the shorted bank. Mine never fires up on all 8 at all.

I am assuming IDM at this point. What is the best route for this? eBay or somewhere else? If it’s eBay, anything to look for to compare or just buy one?

 

The best place for a remanufactured IDM is Jonathan at DTC.

Link: https://www.dieseltechchatt.com

Other than that, go to Riffraff.

Link: https://www.riffraffdiesel.com/idm-7...-module-94-03/

You could try RAE as well.

Link: https://www.remanautoelectronics.com/ford.aspx

 

Ok, I am on the right track. I just got a new IDM yesterday, plugged it in and fired it up. Sounded like it should and idled smooth. We were running out and I have some stuff to put back together under the hood so I couldn't drive it. I am going to get it buttoned up and the IDM mounted this weekend and take it for a drive.

I appreciate everyone's help. I'll let you know when I know I'm back on the road.

 

Ok last bump from me here. I got it fixed with the IDM. Codes are cleared and I have full power and it is driving as it should.

For those that have this problem, follow what is on this thread. If I ran into this now I would do the advice others had given me in this order:

-Run the codes, of course. I bought a $20 USB scanner from Amazon and ran Forscan as recommended. Get a Bluetooth one if you don’t want to tote a laptop with you or want to have it on the go. You’ll spend a little more but it could be worth it if you’re out of town. Run the buzz test and confirm all 8 injectors are firing. I learned that the faint Buzzes are not weak buzzes and that the the other 7 injectors buzz lighter with each individual buzz. It sounds faint because that number injector wasn’t buzzing, in my case all of the odd injectors. Confirmed that I was only running on half an engine with the cylinder contribution test.

-Check the fuel pressure. That gauge in the 2nd or 3rd post costs maybe $15 to make, is reusable, the test does not require you to remove anything from the engine and will rule out the fuel system.

- OHM Test: you only need to remove the pipes to the turbo and the air intake. I would do outside male connection at the valve cover, then the 42 pin, then the IDM.
-if you have an issue on the first one then You need to check the UVCH.

- if the OHMs check out then I would look at the IDM. This is assuming you have The same code and symptoms that I had. Running on half the engine and no change after you unplug the external connector on the VC when running. I can confirm it’s a PITA to get to and get out.

I didn’t have a code scanner and my old multimeter was broken so I did this out of order and wasted a weekend and a half and a couple trips inside the valve covers, and 2 new UVCHs because of this. Learned a lot about the 7.3 in the process though.

Thanks again for all of the help here.

 

Excellent follow up, thanks bud!

 

Thanks for the follow up and info for future readers. Glad you’ve got your truck back on the road!

 

Thank you for closing the loop on your thread. We are all very grateful to hear it is running well again.

Safe travels!

 

This is some great information. Thanks for sharing!