The glow plugs are indepent of the soleniods. They have one wire to each and use the body to block as the ground. The solenoids have two wires going to each. One is common to all of them and the other is the injector low side. So you don't test from injector pins to body ground you want to use the center common Pin (5th one in from the front) to each injector. This gives you the ohm reading across the solenoid and should be around 3.5 ohms. When you test the glow plug you do use a engine or battery ground.

So the pins at the valve cover will be arranged like this:

G G I I C I I G G

G is glow plugs
C Common
I injector

Measure I to C for each injector and G to a good ground

 

To ohm the injector you need to place the ground lead on the center pin, not on the block or frame. To test glow plugs, you need a battery ground. To test the injectors, you have to test the primary wire against the common, center wire (You need to ohm pin #6 against pin #5).

 

Now I'm spooked about the other 7 solenoids reading a reference to ground. Don't put a lot of stock in that, because I've never tried reading reference to ground when doing an injector continuity test. Yes... the center pin is your common for the injectors - it is the power. They use a ground as a trigger for each injector.

 

OK, well then I have a whole new set of problems, because I tried to take the reading from the injectors to the common in the harness and only got open reading which is why I took the reading to ground instead. This really sucks since I can't get this figured out. Both the old and new harnesses have continuity when checked with nothing plugged in.

 

This might sound weird, but clamp your two probes to each other and jiggle the probe wires (like you would a toilet handle). I've had probes go bad on me more than once... as well as cold solder joints on multimeter probe connectors.

Another thing... are you trying to get connection directly through the harness without the VC gasket? It's difficult to make contact on those female fittings, you may need to use an intermediate conductor in the hole - like a paper clip.

 

I was checking the harness without the valve cover gasket, My multi meter has small probes so there is not a problem making contact in the female connecters.

 

Time to ohm and trace the common wire back through the 42 pin connector and back to the IDM.

I don't even remember all the symptoms when this thread started, but it sounds like starting over is the first step. All dash lights function normally? Any blown fuses? Tried swapping the IDM relay for the blower fan relay?

 

I have not pulled the 42 pin connector apart yet, my earlier ohm tests early in this thread were done at the IDM connector so the higher ohm readings were from testing the entire harness. Chris, all the things you mentioned were done and checked before which is why I proceeded to pull the valve covers and suspected the uvch as the problem. I hope to have a chance tomorrow to recheck all the wiring the right way through common as advised, and maybe get better readings.

 

Ok, I made a breakout tool like the one shown in the Ford service manual, so that I could directly test the under valve cover harnesses, and valve cover gaskets independent of the engine wiring harness. I discovered with that tool that the drivers side bank was dead on the injector wiring, and the number 6 glow plug was dead. I changed out the glow plug and installed a new harness and still got no readings on the injectors but good readings on all glow plugs. My passenger side harness that gave good readings is still a bad harness because the retaining clip is broke off, this is the side that fell off when I pulled that valve cover. I then took the passenger side harness, valve cover gasket, and breakout tool and swapped them to the driver side and got good readings on every injector and glow plug. This tells me that the old factory harness on the drivers side failed and both aftermarket replacement harnesses I bought and tested were no good. Tomorrow morning the Ford dealer is supposed to have the retaining clip modification pieces ( the ones that do the same thing as the 50 cent mod) and I will have to buy 2 new Ford harnesses since every harness I have are bad, If one of my IDMs are good this should solve my no start problems. Lesson learned, aftermarket UVCHs are no good, I will post another update once everything is installed and tested. Jim

 

Ok today I got the new under valve cover harnesses from the Ford dealership, I was not pleased that they too are made in China, but they do have more robust connectors to the gasket than the aftermarket ones, I swapped the metal clips that hold the connectors to the solenoids because the ones off the old Ford factory harnesses were thicker and stronger. I tested the harnesses with my breakout tool then tested the entire harness at the IDM connector per GB tech bulletin instructions. All readings were within spec so I attempted to start it with my old IDM installed, no go, so I installed the used replacement I bought off Ebay and it started right up. So to recap the problems all the time were the UVCHs failure that fried the injector driver module. Total repairs that worked came to $188.00 at Ford for two new harnesses and $80 for the used injector driver module. I intend to send the old one to be rebuilt for a spare. Thanks again to everyone who gave me advice I would not have been able to repair this myself without all the help I got from this forum, all my previous diesel experience was with mechanical diesels that don't need electrical components to run. Jim

 

Congrats on getting the truck up and running!! And thanks for letting us know what you found out

 

Yeah, I am very pleased its finally fixed, and it did not cost too much repairing it myself, I've learned enough to keep it running for the many more years that I will need this truck.

 

Congratulations on getting it fixed! I know it's hard to avoid assuming a new part is good, but it happens all too often with aftermarket stuff. Good job and thanks for reporting back!