Do you know what the ohm readings should be when checking from the 42 pin to the IDM?

I'm honestly not sure, but I think it was around 12-13. This was with a 3500# trailer and the truck filled with about 1000-2000 pounds of stuff. Speed was 70-75.

 

If your meter is on ohms and you touch the leads together, it should be slightly more than that. Theres no coil or solenoid to add resistance as there is getting a reading through the injector.

You are checking ea wire. Your leads are basicly going on ea end of the same wire that runs from idm to 42pin. Hopefully i explained that right.

 

Ah okay. Yea I was hoping I wouldn't have to do that because getting to the IDM is a PITA. I'll ohm the IDM out again once I pull it off, then check the harness with a connection on each end. I think I may be able to run a buzz test as well. Found a USB to OBD adapter in a pile of stuff I have in the garage. Going to see if it works with Forscan.

 

Alright, came home today after my car's battery died at work. Fired up the 7.3 to go out and buy a replacement battery. She took a second to start, and when she caught she started loping like a mother ****er. Still no SES light, but I'm guessing it's either wiring harness or UVCH. Going to go through both of them and see what's there. I'm guessing Mr. Mouse and his family made their nest with pieces of my injector wire insulation. Hoping I didn't mess up the 42 pin when I probed it.

 

very thin back probes something like these work great when ohming out wire harnesses . I recently had to Ohm out wires from the PCM to the solenoid pack on my transmission and the regular test leads that come with the multimeter were too fat. Of course using these to stab into wire insulation would not be advised

 

Did you try to drive it? Any power issues? Did you get a scan tool? Try the buzz test again now, if you get faint buzzes on the odds then you’re not firing those injectors.

Could be the loose UVCH connection and need a $0.50 fix

Could be a bad UVCH and need replacing.

Could be (and hopefully not) a short fried another IDM. When my IDM went out I had my passenger side completely out, I would expect a code though.

My thought is still that you have an issue under the valve cover with the UVCH connection at the gasket, likely burnt or causing a short. It just seems too weird that you’re on your 3rd IDM with such low miles. Something is frying them IMO.

 

No way was I driving it. It was surging from 500-1500 rpm just sitting there parked. Not sure how the IDM would be fried so quick. It drove well on the way home from my buddies house, and today was the only time I started it since I drove it back from my friends.

I need to get Forscan set up and do a buzz test. I have the USB to ODB adapter, just need to get Forscan communicating with it.

If it's an issue with the UVCH and I need to pull the valve cover, I'm replacing the gasket and harness. I'm not messing around with shimming a quarter in there. With my luck the connector will break at some point and I'll have a quarter banging around in my valve cover. I'll do both sides as well.

 

Was it a hard start when you had the poor idle? you definitely need a buzz test now. Start it up again and disconnect the external valve cover plug on the passenger side and see if it does anything different. If there is no change then your problem is probably you’re UVCH or IDM.


An arc from a bad connection and/or short in the harness could fry the IDM. I believe a capacitor or something inside, some videos of guys opening up and resoldering a new one in. Above my pay grade.

That could not be the issue and I didn’t mean to push you to wort case. When I was researching for my fix, many users here experienced similar issues that only had a bad connection at the UVCH. Again, so many IDMs in a short period of usage is just odd as there are plenty of trucks running around with 5 times the miles running around on their original. Could be bad luck though I suppose. I still think you are going to find a visibly damaged UVCH under the passenger cover.

As for replacing vs the $0.50 fix, I don’t blame you. I did the same thing. Getting into the valve covers isn’t as difficult as it is inconvenient. And to replacing the driver side too, you can, but probably not necessary. Personally, I would do the passenger side and confirm your ohms and that you’re running right before swapping the driver side if you do.

 

First start was almost normal, took about .1 seconds more than usual, second start took about an extra second. I can almost guarantee it's the UVCH or something in the wiring. I doubt it's injectors, unless the solenoids are fried. Hopefully I can just replace the IDM if it is in fact messed up after this. I bought the 3 year warranty on it.

 

Got the scanner hooked up, pulled a bunch of codes, only two from the PCM though. P1000, which is normal from what I hear, and P0603. Did a buzz test and everything sounded fine, all the injectors sounded the same. Ordered in 2 Dorman UVCH.

Also pulled codes U1262, P0500, U2015, B1483, and P1876. Those don't seem related to the injectors so I'll add that to my list of things to do to this vehicle.

 

If your buzz test sounded fine you should be able to rule out idm and injector solenoids.

You are having an intermittent problem. Clear the codes. Next time you start it need to monitor icp. Need to know if icp maintains when you have your next problem. I guess your uvch could still be the issue. Although i thought you got good resistance readings from the 42 pin connector.

You ordered dorman uvch. I think they redesigned the connector in theirs. A few years ago the dorman uvch was to be avoided. Are any of your other sensors or ipr dorman brand?

 

Everything is original except for IDM and crank sensor. ICP was already checked and it's fine. I did not get "good" readings from the 42 pin. All passenger side sensors were higher than driver side by about 1.5-2 ohms, and 1,3,7 were different from 5. This lined up with the high readings from the IDM connector that I took the day prior. I believe it may be a combined issue between a bad uvch and a wiring harness chewed by mice. The harness was already repaired at a shop once to the best of my knowledge, due to mouse damage. Dorman UVCH had great ratings on amazon and it has the solid internal connector.

 

Well, pulled the fender liner, the air intake, the fuse box mount, and started investigating the wiring under there. Found 2, possibly 3 worn wires, as well as 5-6 wires that had been repaired before. Is it possible to buy a new/reman wiring harness for this for reasonable money? If not I think I may pull the wiring harness and lay it out on the bench so I can go through and fix any issues I come across.

The matting on the fender liner also turned into great nest material for Mr. Mouse.

 

Pulled the valve cover and saw the plug was slightly disconnected. Replaced the UVCH and kept the old one in case this Dorman does indeed **** the bed. Also fixed a bunch of nicked/corroded/broken wires. She fired right up after I got her all back together, and I drove her around the block for about 5 miles. No more DTC's except for a P1876 for a transfer case solenoid. Thanks for all the help.

 

Good job getting it on the road!

I'd have left a nipped quarter in there for insurance against the UVCH backing out again. But I'd leave it for now, the problem may not return.

Did you inspect the underside of the wire harness where it meets the 42 pin? Common place for the wires to wear on the valve cover. Can make intermittent shorts.