So this is gonna be a doozy but i will try to explain everything from the beginning

short version: truck stalls randomly, reduced power, service throttle body, sporatic codes

more context:

about 3 weeks ago end of April ish, I was chasing down a temperature problem. Couldn’t maintain normal operating temp. Changed the thermostat to no avail, replaced the fan clutch and realized that was my problem. Van stay at a nice 200-210 consistently. when I did the fan clutch (don’t ask why) I thought it was a good idea to replace it without removing the top half of the shroud. I pretty much did the install blind.


about a week later (1st week of may) I left my house in the morning, drove for about 45 mins to my first stop. When i left that location, I had an extended crank and no start. Tried about 3 times and the van eventually started. No CEL at the time. Went about my day with no further issues(few short trips, city driving ). At the end of my day heading home I was in traffic. my van just went into reduced power mode, bucking through gears and hesitating. Pulled over and shut it down. Waited a few minutes and started back up with no issues. It did this about 3 times in a 10 mile span. CEL at the time was crankshaft malfunction. That night I went and got a new sensor from the store and replaced it.

following day, my morning commute went without issues. Around noon I was idling and the engine started to stumble and eventually went into reduced power mode again. I shut it off and waited. Started back up with no issues and continued, now a little more worried. On my way home it started to go into reduced power mode and a message on the dash about service throttle starting disabled. CEL was CKP sensor malfunction, ecm malfunction, something about cam sensor. I don’t have the exact codes because I was stalling in traffic so I’m panicking to clear the codes to get moving again. That night I pulled the harness to the CKP sensor to see the wires extremely brittle and frayed. I patched up the wires with tape and heat wrap while I ordered a new pig tail online. I also replaced the ECM with another one that I had on the shelf already programmed to my van.

following day the van ran great, the only CEL was ckp not learned. Ok the van ran great for about a week or more.


yesterday morning after my first stop, the van started to hesitate, stall, and disabled starting. CEL was ckp sensor malfunction, ecm processor malfunction, lost communication with ECM, lost communication with BCM. At this point I had to disconnect the battery and reconnect just to get it home. I got under the van again and saw that the CKP wires were exposed again so i spliced in the new pig tail that came a few days prior. I headed back out to work and a few hours later the van did the same thing and had the same malfunction codes and loss of communication codes so I got it back home as quick as I could.

last night I swapped the original ECM back in just to see what would happen. Now I have a new wave of codes. Knock sensor bank 1 signal and emission purge valve circuit. These codes were never present on the other ECM. Drove around a little today just to be met with the same problem again. Loss of communication with ECM. Ecm module malfunction. I eventually got it home. I’m officially clueless.

i don’t plan to drive it anymore until I figure something out.


I replaced the battery at some point in the past couple weeks as well

if anyone could point me in the right direction to diagnose, I’d be extremely grateful

 

Chances are there are more

 

That crossed my mind but I’m having a hard time finding a new replacement harness. If they’re even obtainable is beyond me. I figured the CKP area was understandable because it’s tucked directly under the exhaust header so the wires were toast. I replaced a good 18” section back where the wires were still soft and pliable.

I’m not sure where all the little grounds on the harness are located as well. I did a ground check on the engine and body back to the battery. I was getting 0 resistance on my digital multimeter

 

that's not right. There should be at least a few milliohms of resistance. Unless you mean the meter was showing OL (over limit or unmeasurable resistance or open circuit in other words)

 

you’re correct. I may have been using the wrong setting. I’m getting 0.33 from - battery terminal to engine block. I’m getting 3.6 from -battery terminal to body. 3.35 -battery to main frame

 

3 ohms is too much. Try to get that down below 1. Clean up the ground and apply some dielectric grease.