Thanks, Andy, and Jeffery for clearing that up, I am going to pull the valve covers to find the short, what do you think of the other readings? All the readings are higher than allowed but #2 is way high at 24.8 ohms. I also checked the ohms at the valve cover connection with the same result dead short on #5. Jim

 

Other readings with that meter are most likely good other than #5 and #2.
When you pull the valve covers you can test right at the injectors and see what the readings are.

 

I read it is possible to replace just the injector solenoids, I don't figure the injectors are shot just yet and I still have the complete spare engine to rob parts for this repair. Jim

 

I have been working so much that I have not had time to tear into my truck, however I did purchase a used IDM for 80.00 and I bought new valve cover gaskets and UVCH wiring harnesses. I plan to re-check the ohm readings at the old UVCH on each side after unplugging them and at each injector and then have my in-law mechanic do a buzz test with his Snap On Tool with the original IDM in place first, then if that fails and after replacing the gaskets and UVCHs and any bad injector solenoids so everything ohms right I will install the replacement IDM and run another buzz test before trying for a start up. Thanks again for all the great advice I received from everyone who answered this thread, and I will post another update when I actually start working on the truck again.

 

That's a long-running project. We wish you luck.

 

Hi everyone, today I finally had time to take the valve covers off my truck, I had not bothered to work on it over the last few months because some P.O.S. stole my battery charger right out of the back of the truck ( camper shell lock did not lock) and I knew I would need another battery charger, which I now have, for the cranking this truck will need after sitting so long. Here is what I found when I got the valve covers off. OHM readings taken at the harnesses with them unplugged from gasket are #1) 2.4, #3) 2.5, #5) no reading, #7) 2.4, #2) 2.5, #4) 2.7, #6) 2.5, #8) 2.4 the passenger side harness was very loose and fell off the gasket when I pulled the cover. I installed the brand new harness on the drivers with no change in the readings. #5 is still dead. I tried swapping injector solenoids on #5 still no change. Before I ran out of daylight I pulled an injector out of my spare junked engine and will get a new O ring kit to install it on Monday. In light of this new information does any one out there have any input? If I get good ohm readings after replacing #5 injector I want to try to start the truck with my original IDM before installing the replacement one. Happy holidays and thanks in advance for any suggestions. Jim

 

The ohm meter only checks the wiring and solenoid side of the injector. If you swapped the solenoid with a known working one, then you don't need to worry about pulling the injector. You need to find the problem in the wiring.

Ohm the #5 pin on each side of the pass thru connector on the valve cover and wiggle the pins as you do it to make sure you don't have a broken pin at the valve cover. Then check the wiring visually and with the meter at the injector plug and the part that plugs into the valve cover. Isolate each thing you can and check the wiring.

The mechanical side of the injector won't have a thing to do with what your ohm meter can read, so I'd leave the injector in place.

 

Thanks, Chris, I took the ohm readings on the uvch with it unplugged from the gasket and #5 was dead with both the old original harness and the brand new replacement harness I also have brand new valve cover gaskets but I am baffled by the bad reading after installing the new wiring.

 

So without even thinking about starting the motor, plug the #3 or #7 wire into the #5 injector and test again with your meter to rule out or confirm the injector solenoid.

 

Ok I will try that, because it seems really strange that after changing the harness out it still is dead on #5. It was only the top part of the injector solenoid I removed and swapped around, if the armature on top of the poppet valve is worn enough to rest on the injector housing I am wondering if that would short out the solenoid. As a precaution the 42 pin connector is currently unplugged from the IDM while working on the UVCH, and won't be plugged in until all ohm readings are right.

 

The solenoid pack is a closed system - continuity would stay the same no matter what happens on the mechanical side of things. While removing solenoid packs for test is OK, I wouldn't disturb the injectors unless I needed to.

Let's break this down into smaller parts: Check the continuity of the #5 wires in the harness without it being connected to anything. If the harness tests good, then while everything is apart - check the continuity of the solenoid pack after inspecting the pins. If the harness doesn't test good, then for fun - find where the continuity of that #5 pin goes to (if it all). I've heard stories of bad Dorman harnesses, this may be one of those events.

 

Thanks, Tugly, I will try that too, I have one more new harness, and one more used one. The passenger side harness that has good continuity has the retaining clip broken off so even the 50 cent mod won't fix it.

 

Okay, Chris, and Rich, I tried swapping wires from #5 to #7 and still open on #5 with the #7 wire plugged to it. I checked both harnesses and got readings on all plugs when unplugged from the solenoids. in desperation I even swapped the #7 solenoid to the #5 injector without unplugging the harness and still no reading on #5 but that was inconclusive account there was no reading when the solenoid went back on #7 until the #7 glow plug wire got plugged back in. Two different harnesses, 4 different solenoids all come up dead on #5 but OHM out perfect on any other injector, Which is why I want to pull #5 injector, I just can't come up with any other solution.

 

Just to be clear, you pulled the wires and took the #7 wire and plugged it into the suspect injector. You stuck your ohm meter on the pin for #7 and it came back open?

You then swapped all the wires back to stock positions and took off the solenoids for #5 and #7, and without unplugging the wiring, and #7 went dead when placed in the #5 hole and stayed dead until you swapped it back and then plugged in the #7 glow plug?

I was starting to think that perhaps there may be some strange issue going on with the armature causing the solenoid to short out, but the part about the glow plug has me confused.

When we're talking about #5, we're talking about the 6th pin in the harness counting from front to back, right? #7 would be the 7th pin, and we're talking about the passenger side of the motor? Where are you placing the ground pin from the ohm meter when doing this test? And just to be complete, do the glow plugs on 5 & 7 both ohm out good? (8th & 9th pins)

 

I had the ohm meter ground pin direct to ground on the head, I too suspected a problem with the armature causing the solenoid to short, but there is proper clearance between the armature and the solenoid. I talked to my mechanic in-law last night and he had a new suggestion, the solenoids use the glow plugs to complete the circuit to ground, so if the #5 glow plug is bad it creates an open circuit. That makes sense since the #7 injector showed open with the glow plug wire unhooked. I have not ohmed the glow plugs but I will replace #5 with a used glow plug from my old engine to see if that solves the problem. Thanks again for the advice, Chris, I will post an update once I swap the plug.