Stumped DTC P1351

I am stumped finding the problem in my 1997 Chev K1500, 5.7 vortec engine, 280,000 miles. The truck always started fine, but it sits most of the time in my driveway. The truck would crank, but not start. I got a P1351 code "Ignition Control Module Circuit High Voltage" which indicated a bad Ignition Control Module. I replaced the ICM and it started immediately. I let it run for about 20 minutes. Turned off, but when I tried to restart it would only crank. Again, I got the P1351 code. After some internet research, I found that this code could also be related to the Cam Position Sensor as well as the Crankshaft Position Sensor. By the way I was getting 55 PSI from the fuel pump. I replaced the Cam Position Sensor. The engine started immediately. Again, I let it run for 20 minutes. Same scenario, P1351 code. Interestingly I was not picking up a P1351 code when the engine was running. I then replaced the Crankshaft Position Sensor. Again, started right up, wouldn’t start again, P1351 code. I purchased a PPECT3000 after watching one of your videos. Started with the ICM, it showed a short circuit. I traced through the harness until the arrow reversed. Open the harness, but there was no break. I am considering buying a Power Probe IV, but I’ve seen some warnings on you site. I’ve also checked my grounds, they are okay. I can well afford to send it out to be fixed, but I am stubborn and want to find the problem. Any ideas and should I invest in the Power Probe IV. Also, would your book help in the instance? Thank you

when you say you checked for a break did you mean visually or you did a wire tug test? Breaks in the wire are sometimes not visible due to the wire sheathing still being intact. So you will want to bend/ flex the wire and see where it bend sharply real easy. that would be a possible break point. Also with both ends of wire disconnected load test it with a 1157 bulb on the bright setting where both filaments light up and see if its a weak break in wiring (light would be dim compared to being hooked up to battery + and -). the other thing to do is check for a broken ground wire and if your getting a ic control signal from pcm. if no control signal it won't ground icm and no spark which means circuit stays at 12 volts which would be your circuit high code. I think on your truck the ground should be on the back of the cylinder head or on firewall. so it will be either in wiring to icm or pcm internal issue

at icm back probe the white wire in slot b and see if you get a signal

then check slot c black wire or black w/ white stripe for continuity to ground and load test it with a bulb or test light (preferably a 1157 bulb or any bulb that will draw 4 amps)

then check power wire terminal a pink wire load testing it as well
if the wires check out good then you will need to see about powers and grounds at pcm and ic signal. if no signal then it is possible pcm is bad.

I would be checking a few things. First I would check coil resistance and the connection. Second I would check the ground for the ICM. Whenever I see "circuit high voltage" codes I always wonder if the ground path is no good. Third how are the cap and rotor? Spark jumping around can cause this. Fourth is it actually a no spark? This code can set from long cranking times. Use of a lab scope is going to really help the diagnostic process.

I will run through the tests you described on Monday. I appreciate the feedback. Will advise on my results. Thank you!

Thanks for your response. The cap and rotor are new. Will continue with the diagnostics tomorrow. I don't have a scope. Will advise progress. Thank you!