Mike, I sure hope you get this thing licked soon.

 

Rich, let me carify. I did not swap injectors. We just swapped solenoids because the codes are electrical in nature. I was told that the buzz test is only a test of the electrical system and that the injector cold be trashed under it and the buzz test would not know if it had a good solenoid on top.

 

The ohm test is showing the same results after swapping the injector solenoid between inj #2 & #4 - but how does the buzz test SOUND on #4 after the solenoid swap? Sharp & snappy like the others?????

 

Double post deleted...

 

Buzz test on #4 still sounds off.

 

I'm guessing your gonna need to pull that injector......

 

I dunno... this sounds electrical to me. The injector could be completely missing, but as long as the solenoid pack is in place - the IDM wouldn't know the difference.

 

Ok, tonight I had a couple minutes to fool with this again. I Ohm'd pins 7 and 23 on the IDM plug with the 42 pin connector plugged together. It came back at 3.2 ohms.

So I guess tomorrow I will ohm pins 7 and 23 to ground indvidually with the injector unplugged. If this doesn't diagnose it I'll be at a complete loss....

My truck is a VDH4 PCM and Doug got me a VDH2 PCM to try. If we don't find a wire issue I think swapping a PCM is my last option. But I really don't see how it could be the PCM.

 

Neither do I. If it was a false DTC report, that would be one thing - but you have a miss. The PCM can't single out an injector and alter how it fires - it just tells the IDM the timing and FIPW, then the IDM takes over.

This is the screwiest electrical issue I've read - I wish I was there to contribute first-hand. Something has to be missed somewhere, or Ohms law has been broken.

 

I have a guy who teaches at a diesel school coming to look at this tonight. He's the same guy that saved my rear end when I screwed up the threads in the snout of the crank installing my fluid dampner. Hope he can figure it out....

 

If he can't find anything I'd move the whole injector to another hole just to see if it follows.

 

A symptom that occurs when the "real" electrons are flowing, but does not seem to show up when a test meter is used is actually quite common in the electrical world. There is a big difference between the few d.c. volts that a meter puts out and the 115 volts d.c. that the injector circuits demand to function properly. A short circuit can occur when operating voltage is applied, but can certainly disappear when a meter is used.


If it was me, I would bite the bullet and cut into the #4 injector wire on both ends, and splice in a temporary wire and then run the engine. Since you have replaced the UVCH, that should eliminate that wiring as a possible problem. The injector does not seem to be the issue, since you are getting a code that can only be attributed to an electrical problem.
An actual electrical "breakout box" would be very helpful at the IDM end of the harness, but would be time consuming to fabricate from known good harnesses.


If you want to try another test of your harness, disconnect all plugs at both IDM and at both valve covers. Rent a "megger" capable of at least 120 volt d.c. volt output. It is basically a high voltage ohmmeter. Test that #4 wire in the harness with the megger. If the wire has good insulation, the megger should show a high resistance to ground that is similar to any of the other injector signal wires. It is possible that a forum member that lives near you may have a megger that you can borrow.
Larry

 

So it turns out not every electrical code is electrical. I pulled the injector, cussed at it, put it into cylinder #2 and put #2 into #4. Hooked the batteries back up and cleared all codes ran a buzz test and got P1272. So my code moved from cylinder #4 to cylinder #2 following the injector. Took it out and off to Baltimore I go this week for a rebuild. Hope this is the end of it...

 

Go Figure. Would have bet the whole wad it was electrical. Lessons learned. Hope this puts an end to it for you Mike.

 

That's bizarre. Did you by any chance name your truck "Stinky" lately?