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Discussion Starter · #1 ·
Truck was working fine, before this mishap. While working on my 1994 OBS Powerstroke, 7.3L, with a screwdriver, I accidentally touched a power source with the IPR Solenoid housing, causing arcing and a black spot on the IPR Solenoid. After this, truck would not start. FORScan diagnostic testing through the OBDII connector revealed a problem in the IPR circuit. By the way, the IPR valve is very new, the HPOP pump is very new, the ICP sensor is very new, and I've verified oil is pumping through the HPOP rails while cranking, but now builds zero pressure (I have a physical pressure guage on the HPOP rails). I check the power/ground leads to the solenoid on the harness (also checked for Oms) and got ZERO volts KOEO on both pins, and I also got an OPEN circuit results for Ohms on both pins comming from the harness. I swapped out the Solenoid with another one I had, and still no start. I swapped out the PCM relay with the horn relay, and still wouldn't start. I checked all fuses inside the cabin and under the hood in the 2 fuse boxes, and all fuses were in tact. Assuming the wiring harness is ok, what are my MOST PROBABLE solutions? Swap out PCM?
 

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Discussion Starter · #2 ·
Oh by the way, today I also ordered a pigtail connector to plug 12V directly into the IPR Solenoid, to see if it starts. I'll have these results midweek.
 

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Check Underhood Fuse #9. Did you get P1283? If so, here are the pinpoint tests. When I got P1283 on my 94, it turned out to be the PCM (last test, all the others passed). Do the tests though. You don't need a breakout box, you can just probe from the PCM connector appropriate pins for these tests. The connector diagram is for pin numbering reference only. Cheers!
 

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Discussion Starter · #4 ·
Check Underhood Fuse #9. Did you get P1283? If so, here are the pinpoint tests. When I got P1283 on my 94, it turned out to be the PCM (last test, all the others passed). Do the tests though. You don't need a breakout box, you can just probe from the PCM connector appropriate pins for these tests. The connector diagram is for pin numbering reference only. Cheers!

Thanks Patrick! I'll start probing around...
 

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Discussion Starter · #5 ·
Patrick, I ran all the tests and found X1 (Power Feed Short) to be the culprit. Makes sense, since no power was initially detected at the IPR connector. I expanded the testing on X1 step:
Test between PCM relay terminal 361 and Test Pin 83. This was less than 5 ohms, indicating that the burnt/open wire event was NOT between the relay and the PCM connector. Therefore, the burnt/open wire must be BETWEEN the relay and the IPR connector, as the X1 test proved by finding open circuit in this segment. My guess is that the place where the IPR Red wire connects to the harness (if that exists) or somewhere along the wire, or at the ends. I'll hunt it down. So happy so far, since this looks like i DID NOT fry the PCM (fingers crossed). I expect that if I fix the short, it'll start up just fine. I'll let you know.
 

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Discussion Starter · #6 ·
Problem Solved: User error. When disconnecting all electrical connections when I tore down the HPOP pump for leak resolution, I evidently forgot to plug in the harness that connects to the IPR. When I tried to hunt down my IPR power loss issue, I traced the line from the IPR to an uplugged connector - Dough! Sorry guys! My bad. Reconnected and the truck started like a champ and is going strong.
 

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The final outcome is what matters! Glad it's fixed with no PCM replacement. Cheers!
 
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