Hey there, im in desperate need of figuring out ecm/pcm problems. I own 2000 automatic 4wd truck, a mechanic said the original ecm was bad so he sourced an ecm p/n 3947912(2002?) truck would start and run but rpm would cut out after 5 seconds of run time.(im aware newer years didn’t have a crank sensor). Fast forward i bought a 2000 donor truck with a manual transmission , I removed the ecm/pcm and all wiring harnesses under the hood and swapped them to my truck(one thing i noticed on the donor truck was it has a crank sensor by the starter but nothing was plugged into it and there was no pigtail in the harness) so i swapped all mentioned above into my truck and I’m still having the same rpm issue as well as throwing a code for no crank sensor signal. Do I need to swap the entire fusebox wiring harness and whatever is included on it to get my truck to not try and read the crank sensor signal? 

01-02 all have their crank sensors on the timing case by the VP44. My 01 does and has a blank plug in the old spot by the starter.

 

If you don’t have any crank sensor hooked up whether old style or new style your gonna have a problem. The ecm needs to see engine timing. 

 

Once that is figured out all you need to do is take your truck to a dealership and have them program the ecm/pcm against the vin so it’ll act like it originally intended.

Edited March 5Mar 5 by Mace

Contact @Auto Computer Specialist and they can flash program both ECM and PCM for manual software and get the right software for your application to reduce the weirdness.

 

More on the different series of 24V...

https://mopar1973man.com/cummins/articles.html/24-valve-2nd-generation_50/51_engine/swapping-vp44-cummins-engine-between-985-00-01-02-r429/?do=getNewComment&d=4&id=429

@Mopar1973Man do I need to put the original harness back in that had the crank sensor plug or use the harness that came with manual truck that does not have a crank sensor plug by starter?

Also one thing I did notice is the manual motor is isb235 and the automatic motor is isb215 not sure if that makes a difference 

  On 3/5/2025 at 5:10 PM, Trey2maxwell said:

@Mopar1973Man do I need to put the original harness back in that had the crank sensor plug or use the harness that came with manual truck that does not have a crank sensor plug by starter?

Also one thing I did notice is the manual motor is isb235 and the automatic motor is isb215 not sure if that makes a difference 

 

YES! Then you need the proper software on both ECM and PCM and everything works out fine.