PCM intermittent power or bad ground?

[JCart]

Hey Fellas,
Need some insight, buddies 97 7.3 ZF-5 quit today after hitting a larger bump/rough spot on the highway. Truck shut down, will not fire. I gave him an ECM a couple weeks ago as he experienced same, installed my ALF4 ECM truck fired right up. Sent other ECM off for suspected repair.

Im thinking short to PCM as it shut down after the bump, first stock one failed driving on bumpy gravel road.
Not looked under hood just yet, think he said all fuses were good even under hood ones. Has disconnected fuel bowl heater.
Any suggestions? Gonna clean up the ground line to fender for the PCM to ensure it has a good connection.

What else should we be doing.
Tia
j

 

[JCart]

All right checked all fuses, they’re good. Checked IPR plug for loose insulation and shorting nothing. Pulled out PCM pulled cover off and looked at circuit board, no burnt smell nothing looked melted. Cleaned ground wire for PCM on inside fender by hood spring. Grounded (with jumper cable) to fender brace by battery and Air cleaner, for solid grounding for PCM. Hooked autoenginuity to port inside cab and it wouldn’t connect to PCM. Idle module screen said C err, no “wait to start” light, but brake light and glow plug light do light up.

Kinda perplexed…. Any suggestions be appreciated
Thanks
j

 

[Patrick Feeley]

With no WTS, maybe check the connectors and wiring harness(es) near any of the sensors that use the 5V reference voltage the PCM provides (TPS, BARO, CPS, EBP, ICP, MAP). Cheers!

 

[JCart]

With no WTS, maybe check the connectors and wiring harness(es) near any of the sensors that use the 5V reference voltage the PCM provides (TPS, BARO, CPS, EBP, ICP, MAP). Cheers!

Thanks Patrick, good points!