I am perplexed
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4wd Low
Joined: Jun 2019
Posts: 10
Likes: 3
I am perplexed
So, my issue is that # 5 fails a buzz test and when I start the truck it shuts that bank down completely. If I unplug #5 pin at uhvc harness the truck will run on 7 cylinders, i.e. won't shut the bank down so I know #5 is the problem child. While trying to figure out if its injector or harness side, I swapped pin 5 and 7. Originally #5 was the only problem on buzz test, now ever since the swap it has been #5 & #7 failing the buzz test. Move forward to a week ago I said let me swap #5 with #1 pin just to double make sure, so I did. NOW #1 #5 #7 ARE ALL FAIILING THE BUZZ TEST. WTF IS THIS WITCHCRAFT. NUMBER 5 BUZZ TEST CAN BARELY BE HEARD SO ITS DEFINITLY SOMETHING IN THAT CIRCUIT. I took my IDM out and put in my dad's exact same truck and it ran fine. I replaced the #5 injector and engine harness. I checked the truck side harness for damage of any kind and cannot find anything wrong; I even did the tug test thinking maybe a wire broke internally. I did the ohm test at IDM and every circuit read 2.7. I checked every ground known to man. I have good engine ground as well as body and frame ground. I took out my tuner as well. I want to just order a IDM but dang it ran good in my dad's truck so that doesn't make any sense that it could be bad. What am I missing here? ALSO, UHVC GASKETS ARE NEW MOTORCRAFT GASKETS.
FTE Chapter Leader
Joined: Jan 2005
Posts: 13,076
Likes: 4,692
From: Henderson, NV
My theory is there is a short in the original #5 injector solenoid that killed the #5 injector driver. When you swapped, that bad solenoid killed the #1 and #7 drivers also.
Last edited by FordTruckNoob; Feb 18, 2026 at 07:23 PM.
Thread Starter
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4wd Low
Joined: Jun 2019
Posts: 10
Likes: 3
And that makes sense, however I have swapped the IDM over a couple of times, and it has always seemed to work in my dad's truck, how can that be? At this point I believe I will just buy a new IDM from diesel technology.
Lead Driver
Joined: Jul 2003
Posts: 7,404
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From: Wheatland, Mo
Being that your problem is all in the driver's side, have you checked the underside of the harness going over the valve cover? It's a common issue to have wires rub thru and short out against the valve cover
Or do I have the cylinder banks swapped in my head?
Or do I have the cylinder banks swapped in my head?
Last edited by BillyBob69; Feb 19, 2026 at 06:53 AM.
Lead Driver
Joined: Apr 2016
Posts: 7,170
Likes: 1,331
From: Bahstun
swap wiring harness and see if the problem follows?
https://www.ford-trucks.com/forums/1...load-test.html
nice chart to ohm out fast
https://www.ford-trucks.com/forums/1...load-test.html
nice chart to ohm out fast
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