I am in the middle of a 3.9 to 5.2 swap on my 2003 2wd. I ran my 3.9 up to 223,495 miles before it gave up. I have the 5.2 at the machine shop right now and i am going to start putting it back together this weekend. My question (That i haven't found an answer to after searching everywhere) is about the PCM. Would i be better off with a PCM from a 1999 Dakota 5.2, a 2003 Dakota 5.9, or the original donor vehicle which was a 1998 Ram 5.2. Basically should i go with the same year dak with a different engine, or a different year dak with the same engine?

 

The 5.9 PCM will be configured on the rich side for the 5.9.

You're best off with a reflashed PCM, but worst case, you might try the 99 5.2, but I think it will be wrong since alot of things changed in '00.

 

I would have to say that if you are using the transmission that is with the donor engine, that you use the Ram's PCM since it was optimized for that engine transmission combination despite being made for a heavier vehicle.
The 2003 Dak PCM is "programmed" to be most effective with the 5.9 despite it being the same engine as the 5.2l.
Since the 1999 Dak PCM is for a 5.2 and it is in the same "generation" as your truck, and the vehicle really didn't change during the 4 year difference between donor PCM and receiving truck. It would be the best "match" since it already knows the vehicle weight, engine/transmission specs and all of the minor details like lights and gauges.

This is in no way an expert analysis of your problem but it should help you get your truck closer to being roadworthy. Good luck.

 

@ Magnethead
The engine is from a 98 Ram so how would there really be an issue when using the 99 Dakota PCM. The primary changes in 00 from my understanding of the ALLPAR.com info were to accommodate the 4.7l and a better front suspension.

 

The dash was changed significantly, though I think all electrical stayed generally the same. I know my 01 FSM and my haynes manual outline some places where wiring was different during the changeover.

 

Hang on guys, 2003 truck means PCI bus for communications. The older, pre-2001 CCD bus will not work.

There was a major change electrically between 2000 and 2001.

Use the newer 2003 PCM. You need it for the dash and other functions to work.