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Discussion Starter #1
From what I've read, there are some really smart guys here when it comes to these 7.3 trucks. And I'm pulling my hair out here. I'd appreciate any help you guys can give. Told a friend from work I'd look at his truck. He said it would momentarily cut out every now and then, sometimes just die. At an idle, driving down the street, and it would pretty much always start back up. He also said he's put 8 batteries in it in 2 years. So, he brings it over, I start doing checks once I see it happen.

When it cuts out momentarily, the check engine light, WTS light, Water in Fuel light all come on. Now, I made a stupid assumption that the WTS light comes on when the PCM is first powered up. And I realize he was putting batteries in it so often because every time it glitched or cut out, it would begin the glow plug cycle over. So, between that and the WTS light, and the fact it will sometimes lose power on the control side of the IDM relay, I assumed the PCM must be resetting.

He wanted to just put a PCM in it, so he got one. That didn't fix it. I pulled wiring diagrams and module pin out info. I found 3 power feeds and 3 grounds for the PCM. Every ground can carry the load of a bright 5amp light, and none of the power feeds are losing voltage when it happens, but it will occasionally cut out and decide to turn off the IDM relay.

I don't know these trucks, I don't usually work on diesels much. I'm about to tell him that he needs to take it to someone more familiar with diesels than me, but my pride is really fighting that one.

Thanks in advance for any help.

It did set a few codes, I'll include them.
765944

765945
 

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No, I think you're on the wrong track ;)

#1 the WTS coming on is a good indication that the PCM is actually running (often power problems to the PCM supply are a problem, if you see that All Important WTS it means the PCM is booting-up like it should). The WTS is NO INDICATION of Glow Plug Operation though (it's ON when they're Not and OFF when they Are ~ in many cases) so, wouldn't have Anything to do with needing batteries so often (is he buying cheap batteries because they keep going bad?)

#2 there are IDM codes but there is a procedure called a "Buzz Test" you need to perform that causes the IDM to do a Self Test and can resolve more specific codes once completed.

#3 you have a 1211 out-of-spec ICP pressure and that's not something to take lightly, gotta find out what's going on there.

#4 I can't tell what it is you're using to scan with but, we need special sw to properly scan our systems which are not, specifically just OBD-II. It takes both the Ford Specific and Diesel Specific libraries of codes as well as the SAE J1850 communication protocol.

BUT,,,, IDM and ICP problems don't usually cause your friends symptoms. It runs, dies, and restarts easily? That's more likely something like the CPS which, once once it stops sending RPM signal to the PCM, the PCM will shut down the IDM (needs to see a min of 100rpm to start & run before it triggers the injectors). CPS problems are common with both the early Ford/IH sensors (Black Plastic Housing) and Most aftermarket CPS's. Be sure of what sensor in installed.

The next most likely culprit, especially with HiPres Oil codes, might be the IPR valve. It can get stuck Open and keep the pressure lower that it can run with (and monitoring the IPR values is only what the PCM is Commanding the IPR to do , Not what it may be actually doing).

BUT,,,, both these issues usually require a "cooling off" period to restart again (except maybe an aftermarket CPS which are just So Problematic they might do Anything ;)).
 

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Thank you for the info. I struggled to find good info on this truck, even with the service info access I have for it. It was actually further into the diagnosis that I figured the glow plug issue. See, using a scope to check power into and out of the ignition switch I would see the system voltage at like 12.2, then a minute or two after starting, it would jump to about 13.8. Trying to track that down its when I actually found and verified that the glow plug relay is turned on again every time this happens. Man... that draw some power off the system.

I'm using a Verus to scan, and for what I paid for it... I'm rather frustrated I'm unable to read IDM codes or communicate with that module. After posting, I did find the Injector Buzz test and ran it. There were 2 that sounded different, and it showed an Injector 8 Circuit Low fault. That led me to check the wiring harness and find what might be the worst thing I've run into in recent history for wire repair. Someone replaced the pigtails where they plug through the valve cover and with the bundle of bare wire hanging out... I didn't think it was a good job.

So, finding out he had the injectors all replaced a few months ago and seeing that, in addition to not being able to communicate with the IDM. I told him I'd reached the limit of what I could do and his best bet was to take it back to the shop that did the injectors. I hated to do that, but I'm a firm believer in knowing the limits of your knowledge, experience, and equipment.

I do greatly appreciate the reply, thank you again. I can hold my own on any gas vehicle thrown at me, but these diesels are a different beast. I've got to do some learning.
 

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Sounds like you were "almost there" in fixing your buddy's truck -- people like to replace the CPS pigtail as well, and if the wiring job was like the under valve cover job, ..well then you get where my thoughts are going
The Versus is a good tool, but ForScan may outdo it in some respects, it is tailored to these trucks
Injector circuit low, means to a powerstroke, that the injector is pulling low amps - so usually a bad connection -- the injectors are the only circuit that is measured in amps load
There is a high chance that the engine harness may be toast -- some insulation would turn to goo, while other would harden and flake off -- I think Ford was experimenting ...lol
The CPS thing can be caused by a tip clearance being wrong, the sensor needs to be "close but not touch", so like .003-.005 --- I suspect a lot of the "failures" are actually clearance problems with the cheap manufacturing we have these days
 

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Thank you for the info. I struggled to find good info on this truck, even with the service info access I have for it. It was actually further into the diagnosis that I figured the glow plug issue. See, using a scope to check power into and out of the ignition switch I would see the system voltage at like 12.2, then a minute or two after starting, it would jump to about 13.8. Trying to track that down its when I actually found and verified that the glow plug relay is turned on again every time this happens. Man... that draw some power off the system.
Sorry, but again,No ;)

The GPs activate only when the EOT sensor is below a certain threshold NOT every time you start. I believe what you're seeing is the PCMs management of the Alt output (so as not to compete with the GP draw, it "delays" the Alt from from charging for a bit ~I think,,.)

With almost any Android device (phone Tablet etc) you can get the ForScan app Hydro refereed to.

If you're gonna keep & maintain the truck yourself I strongly suggest you get access to the special scanner software you need to do it.
To retrieve most of the codes you'll need to help and even do some testing look at the FORscan Lite or TorqueApp (you add an Android device and Blue Tooth Adapter for @ $30) OR the Windoze version with a USB adapter. I like this one for BT Android -> Amazon.com: Bafx Products - Wireless Bluetooth OBD2 / OBDII Diagnostic Car Scanner & Reader Tool for Android Devices - Read/Clear Your Check Engine Light & Much More: Automotive

Just a few years ago you needed to buy a professional scan tool because our trucks need to have a scanner with a Library containing both the Ford Proprietary AND the Diesel Specific codes in it. Add to that, our trucks are Not, specifically, OBD-II so the Generic scanners the Auto Parts Stores have are of little use to us. But today there are some very good App based tools, that are close to what the pro tools do, for fraction of the cost.



 
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