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I was just chatting with SSJ about the CPS install "fixing" your issue. I guess I spoke too soon. I told him my suspicion was that the connector or the wiring to the CPS was at fault, not the sensor itself.
Although, the other fellas bring up a good point that the problem may be near the PCM, which makes tracking it down much more difficult.
I was just chatting with SSJ about the CPS install "fixing" your issue. I guess I spoke too soon. I told him my suspicion was that the connector or the wiring to the CPS was at fault, not the sensor itself.
Although, the other fellas bring up a good point that the problem may be near the PCM, which makes tracking it down much more difficult.
Keep us updated!
Definitely much more difficult. I pulled the PCM back out and have it connected in the fender well. Vref is back in the 200mV range. Perhaps that wire is shorted between the 42-pin and the PCM. The only way to know is the unwrap all the wire loom.
Definitely much more difficult. I pulled the PCM back out and have it connected in the fender well. Vref is back in the 200mV range. Perhaps that wire is shorted between the 42-pin and the PCM. The only way to know is the unwrap all the wire loom.
That is definitely the way to go. I had mine out when the engine was sent away to be rebuilt. I went over it with a fine-tooth comb, checking for shorts and continuity on all circuits, replacing pigtails, re-wrapping the EMI shield and cleaning the heck out of it. It looked like a brand new harness by the time I got done. It is not as hard to take the whole thing out as it looks.
In addition, below is a list of the pinpoint tests available in the PC/ED portion of the FSM. There are other tests, procedures and diagrams in the workshop and wiring diagram section, but they are much more difficult to navigate (for me anyway). If you need something else, we can get it, just might take a bit to find it. Everything and anything is in this manual, just have to know where to look.
FTN, I’d love to do that but am running out of time quickly as I have to return to Tucson today.
Thanks for the tests Sous. I’m going to give those a shot, take a look at the 42-pin wiring to the PCM, then if all else fails I’m going to have to have it towed to a shop tomorrow. My daughter will follow the tow rig and take the keys to the shop for me.
Well, time is up. I ha e to head back home. The truck is going into the shop tomorrow. I believe I’ve narrowed it down to a short in the vref line but don’t have anymore time to search for it. I’ll keep you all informed as to what the shop finds and fixes. It’s a local diesel place that a buddy with a 7.3 highly recommended.
As a side note, where did you get the FSM? I’d like to purchase one for future use.
FTN, I’d love to do that but am running out of time quickly as I have to return to Tucson today.
Thanks for the tests Sous. I’m going to give those a shot, take a look at the 42-pin wiring to the PCM, then if all else fails I’m going to have to have it towed to a shop tomorrow. My daughter will follow the tow rig and take the keys to the shop for me.
Well, time is up. I ha e to head back home. The truck is going into the shop tomorrow. I believe I’ve narrowed it down to a short in the vref line but don’t have anymore time to search for it. I’ll keep you all informed as to what the shop finds and fixes. It’s a local diesel place that a buddy with a 7.3 highly recommended.
As a side note, where did you get the FSM? I’d like to purchase one for future use.
Well crap... I was hoping to check back and see a "SUCCESS!!!!" from you @ztodd377 .
We understand taking it to a shop and no one will fault you for that because you have certainly done everything you could given the time you had.
I sent you a PM about the FSM. Just check it when you get a moment and get back to me.
Thank you all for your help during this issue. All the ideas and new directions helped tremendously. I just wish I'd had more time, and would love to do what FTN did with the main wiring harness. Maybe one of these days I'll be able to. For now I'm back in Tucson and will call the shop in Albuquerque tomorrow and have the truck towed over. I will keep you all posted on what the killer item turns out to be.
Well, the shop called and the truck is fixed. I replaced the ICP sensor and pigtail a couple of months ago. When they opened the wire loom on the harness they said it looked like the ICP pigtail had been replace sometime previously but apparently the wires were left bare (who the hell knows why) and they eventually started shorting out against each other and that's what was killing the vref signal to the PCM. Old PCM is back in they said and it's running. Thanks for all the help and it appeared we were on the right track with the vref.
So are you saying there was an ICP sensor pigtail replacement prior to yours and that one had wires left bare? That's why I always cut back into the harness far enough to find fresh-looking wire when I replace pigtails.
FTN, exactly. He said whoever replace the ICP pigtail previously had used butt connectors and they were slipping off now (forgot to put that in the previous post) and allowing the bare wires to touch and kill the vref.
Once I go pick it up this weekend I'll install the Hydra and see how that goes.
