1995 7.3PSD Crank no start, Suspect PCM
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4wd Low
Joined: May 2020
Posts: 11
Likes: 2
From: MT
1995 7.3PSD Crank no start, Suspect PCM
1995 F350, CabChassis, ZF5, PCM DPC-203
Need help verifying my diagnosis before I drop money on a PCM
Problem: Original Failure happed when old man was driving truck, said it would start hard and die repeatedly some mornings till it would finally catch and stay running. He was driving it a couple days later and it started cutting out on him like somebody was turning key on and off until it sputtered and died. Had to tow pickup home, thought CPS was the issue. Replace CPS with little to no improvement, truck would occasionally start and run for a couple seconds and die, now truck wont start period. If i forgot any information i will be sure to update post.
Symptoms:
Need help verifying my diagnosis before I drop money on a PCM
Problem: Original Failure happed when old man was driving truck, said it would start hard and die repeatedly some mornings till it would finally catch and stay running. He was driving it a couple days later and it started cutting out on him like somebody was turning key on and off until it sputtered and died. Had to tow pickup home, thought CPS was the issue. Replace CPS with little to no improvement, truck would occasionally start and run for a couple seconds and die, now truck wont start period. If i forgot any information i will be sure to update post.
Symptoms:
- Low side oil pressure builds and holds while cranking, HPOP Resiviour is full
- Watching data stream on ForScan shows ICP at 200psi MAX, usually lower.
- IPR Duty Cycle at 50% While Cranking.
- CPS Signal is present, shows ~200rpm on Tach while cranking
- Good Fuel Pressure ~55-60psi (E-Fuel System)
- No visible smoke from tailpipe
- Cranking with valve covers off, can not see any visible leaks, no oil passing through injectors
- Recieving 12v but no ground signal at IPR when testing with noid light
- PCM Powering up, CEL illuminates, Sends power to IDM, Etc.
- Injector O-Rings were de-laminating. Replaced All 8
- HPOP Recently Replaced
- IPR Recently Replaced
- ICP Good
- IDM Tested Good
- New Motorcraft CPS, Harness continuity checked from PCM to CPS Pigtail, Low Resistance, No visible issues
- UVCHs and Pigtails good, continuity checked from IDM to internal Connectors, Low Resistance, No visible issues
- Verified Wiring from PCM to IPR, continuity good, Low Resistance, No visible issues
- Verified PCM Ground
Butt-Head
Joined: Apr 2004
Posts: 9,432
Likes: 2,919
From: Reed Point, MT
200 PSI while cranking at a commanded 50% duty cycle does raise flags. It's easy to tell if it's control side problems or leakage/hydraulic part problems.
Put 12V straight to the IPR connector (limit time to under a minute though - it'll get hot). If it starts, either the IPR wiring from the PCM is bad (since you say you have 12v at the red wire when the key is on) or the IPR driver in the PCM is bad.
If it still doesn't start, you need to start testing for leaks.
Put 12V straight to the IPR connector (limit time to under a minute though - it'll get hot). If it starts, either the IPR wiring from the PCM is bad (since you say you have 12v at the red wire when the key is on) or the IPR driver in the PCM is bad.
If it still doesn't start, you need to start testing for leaks.
Last edited by cleatus12r; Apr 13, 2026 at 10:11 AM.
Thread Starter
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4wd Low
Joined: May 2020
Posts: 11
Likes: 2
From: MT
Update:
@cleatus12r I tried direct 12v to IPR and it didnt muster up much oil pressure, but ive also had the HPOP system open multiple times and there could be excess air in the system. However, I'm not getting any oil through injectors, even with constant 12v to IPR, its dry as a bone up top.
Pretty sure IDM isnt getting Fuel Delivery Signal from pcm, infact the pcm may not be communicating with the IDM at all. I am unable to perform a buzz test using ForScan.
I verified all wiring between PCM and IDM, which leads me to believe PCM is toast. May have a loaner known-good PCM sourced. Will install and post results!
@cleatus12r I tried direct 12v to IPR and it didnt muster up much oil pressure, but ive also had the HPOP system open multiple times and there could be excess air in the system. However, I'm not getting any oil through injectors, even with constant 12v to IPR, its dry as a bone up top.
Pretty sure IDM isnt getting Fuel Delivery Signal from pcm, infact the pcm may not be communicating with the IDM at all. I am unable to perform a buzz test using ForScan.
I verified all wiring between PCM and IDM, which leads me to believe PCM is toast. May have a loaner known-good PCM sourced. Will install and post results!
Butt-Head
Joined: Apr 2004
Posts: 9,432
Likes: 2,919
From: Reed Point, MT
Update:
@cleatus12r I tried direct 12v to IPR and it didnt muster up much oil pressure, but ive also had the HPOP system open multiple times and there could be excess air in the system. However, I'm not getting any oil through injectors, even with constant 12v to IPR, its dry as a bone up top.
Pretty sure IDM isnt getting Fuel Delivery Signal from pcm, infact the pcm may not be communicating with the IDM at all. I am unable to perform a buzz test using ForScan.
I verified all wiring between PCM and IDM, which leads me to believe PCM is toast. May have a loaner known-good PCM sourced. Will install and post results!
@cleatus12r I tried direct 12v to IPR and it didnt muster up much oil pressure, but ive also had the HPOP system open multiple times and there could be excess air in the system. However, I'm not getting any oil through injectors, even with constant 12v to IPR, its dry as a bone up top.
Pretty sure IDM isnt getting Fuel Delivery Signal from pcm, infact the pcm may not be communicating with the IDM at all. I am unable to perform a buzz test using ForScan.
I verified all wiring between PCM and IDM, which leads me to believe PCM is toast. May have a loaner known-good PCM sourced. Will install and post results!
Thread Starter
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4wd Low
Joined: May 2020
Posts: 11
Likes: 2
From: MT
I understand the IDM has no part in building pressure, I was just adding additional info regarding the PCM. I am unable to perform any IDM commands and, unless I'm mistaken, the PCM acts as the communication gateway to the IDM.
As far as not building HPO, I will continue to diagnose that issue tonight.
As far as not building HPO, I will continue to diagnose that issue tonight.
Thread Starter
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4wd Low
Joined: May 2020
Posts: 11
Likes: 2
From: MT
Update:
Gave the IPR 12v direct and jumped the starter solenoid, she built 500+ psi and lit pretty quick. It was fast enough it made me flinch.
So HPOP circuit is good, its purely a control side issue now. Looking like PCM is the culprit,
I also called Ford and give them VIIN and PCM Batch Code, and they said that PCM is not the original for the vin. so that's interesting.
Gave the IPR 12v direct and jumped the starter solenoid, she built 500+ psi and lit pretty quick. It was fast enough it made me flinch.
So HPOP circuit is good, its purely a control side issue now. Looking like PCM is the culprit,
I also called Ford and give them VIIN and PCM Batch Code, and they said that PCM is not the original for the vin. so that's interesting.
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Thread Starter
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4wd Low
Joined: May 2020
Posts: 11
Likes: 2
From: MT
Butt-Head
Joined: Apr 2004
Posts: 9,432
Likes: 2,919
From: Reed Point, MT
Update:
Gave the IPR 12v direct and jumped the starter solenoid, she built 500+ psi and lit pretty quick. It was fast enough it made me flinch.
So HPOP circuit is good, its purely a control side issue now. Looking like PCM is the culprit,
I also called Ford and give them VIIN and PCM Batch Code, and they said that PCM is not the original for the vin. so that's interesting.
Gave the IPR 12v direct and jumped the starter solenoid, she built 500+ psi and lit pretty quick. It was fast enough it made me flinch.
So HPOP circuit is good, its purely a control side issue now. Looking like PCM is the culprit,
I also called Ford and give them VIIN and PCM Batch Code, and they said that PCM is not the original for the vin. so that's interesting.
If you have done your due diligence with diagnostics and you do need a pcm, make sure that your IPR harness (the two wires where they connect to the IPR) has not been ruined due to fuel intrusion in the insulation. There are circuit protections in the PCM for a shorted harness but they can only take being shorted so many times before the driver burns up. You don't want to ruin another PCM if that's the case.
Lead Driver
Joined: Jun 2004
Posts: 6,321
Likes: 584
From: Amarillo, TEXAS!
Use an incandescent test light to check for power at the IPR connector. It will probably be dim at key on, but should get fairly bright while cranking. It would be even better if you had an oscilloscope and could back probe the connector to watch voltage and duty cycle with the IPR valve still in the circuit. If there's a point of high resistance in the circuit, a multimeter will still read voltage because it puts very little load on the circuit, so that can be pretty deceptive. It's almost never the PCM.
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