Thanks, I will do so.

 

On my connect diagram it shows the red wire to the right, standing in front of the truck. Don't know for a fact but that is what it shows.

 

Jim thanks for your assistance in regarding the IPR voltage. Today, I tried starting the truck and crank, crank, crank.
I checked the IPR volts 12 + hot wire and 0.8 for the yellow/red. I knew it used to be 0.36 or so when it would start.
I started wiggling the main engine harness all over and all at once I had no volts. Then, I had from 0.07 to 0.36 or so. WTH! I had soldered my connections and I knew they weren't coming apart, so I started pulling the harness apart. Then the volts went up to 0.8, stayed there till I got all the way to the 42 pin plug. I started moving wires around till I found the yellow/red and all of a sudden my volts went to 0.36 and stayed that way. The wire wasn't loose though.
So, I jumped in truck and tried to start it. Lo and behold by the grace of god, it started in 2 seconds.
I shut it down taped up the harness and kept checking volts as I did and it stayed at 0.36.
Now it starts and idles great. It stuttered once or twice but it may have some air in the system. When I get the air cleaner back on, I'll take it for a spin.
A little unnerving though. No bare wires, no loose wires. What do you think? It purrs like a tomcat in a creamery right now though.

 

I get "most improved" award.

 

WOW, at least it started. (post # 200)

 

What specific harness was the loose wire at?

 

What I think, and I am not sure yet, because I haven't driven the truck around much, but maybe this was the problem:
The red/yellow wire from the main engine harness goes into the female 42 pin connector right under the back of the air filter. The red/yellow wire enters the harness close to the middle and it was really crammed up against a couple other wires. Maybe one of the other wires was 12 volts and there was a little leakage to the yellow/red. I don't know for sure, that is why I said it is unnerving. i was hoping to find a bare or loose wire, but didn't. Time will tell if my CEL problem goes away. Another problem was the air cleaner canister was wedged against the harness.

 

Suspect the yellow wire is broken somewhere inside the insulation. This usually occurs at flex points and is extremely hard to find. It would cause your symptom of 12 volts on each wire at times. Sometimes you can run your fingernail over the wire and feel the break (indentation), sometimes not. Assuming the problem is not in the actual 42 pin connector replacing the yellow might be an option, as close as possible to the 42 pin connection as possible.

I've found another technique that works well in these type of problems. Get a small straight pin and stick it through the insulation at various points along the yellow wire and do voltage checks, usually some loss of blood occurs, at least for me. If you find a big difference between two points then you know where the bad section of wire is.

Hopefully none of the above is required and you can keep trucking, but if not something else to try.

 

At least I believe we are narrowing in on the problem. I guess if Ihave to replace the yellow wire, I'll just run it along the harness. I'm not taking all that apart again. Thanks for the suggestion, if I have further problems I have something else to do.

 

I'm terrible at electrical, I would replace the wire harness.

 

Looking good so far! Got up this morning and turned over the engine, and it started in a few seconds.
I didn't check the HPOP resevoir, but it must have been fairly full. Now to drive it for awhile and see if the problem comes back. At least I think it is isolated to the yellow/red wire or the 42 pin plug.

 

Very cool and glad it's fixed or narrowed down...excellent trouble shooting tip with the "straight Pin" Jim...as these trucks get older by the day, extreme heat and the such, you gotta think more of the Harnesses are getting brittle....and problems down the road...looks like a "cottage" industry could be started by building new / Improved Harness...LOL
I bought my IPR harness off eBay and was very pleased with what I received.

 

I was really surprised when I tore the harness apart, how good everything looked. Almost like new and my truck has 286000 miles on it, and I live in hot Bakersfield, Ca.
I drove it around the block a couple of times today and not a miss or a stutter. Keeping my fingers crossed.

 

I told you that Jim is an electric/electronics MASTER GURU. He is the man!

I hope everything is going well.

 

Thanks for getting him involved Roen