Ok, here is my issue, I recently wrecked my 2002 Ram 2500 H.O. 6 speed and totaled it out.  It only has 97,000 miles so I purchased a 1999 3500 with Cummins and an auto tranny to put my motor and transmission in.  I have completed the engine and transmission swap and all is well....almost.  The cruise will no longer work, the light won’t even come on in the dash. It worked on both trucks before the swap. 
 

Here’s another known problem, the 1999 truck had the vacuum actuator under the driver’s side battery for the cc and the 2002 cruise control is all electronic controlled.  I used the pcm and ecm from the 2002 so I didn’t hook the vacuum actuator up as the 2002 didn’t use it. Any suggestions would be great. 
 

Thanks,

I would guess the 02 electronics are looking for some signal the the 99 cant produce since none of them were fly by wire. Plus you have manual electronics on an auto truck. Did have the 02 electronics reflashed to an auto?

Edited November 28, 20204 yr by dripley

    A manual transmission PCM will not work for a auto transmission cruise control that has a vacuum controller.

I do have manual electronics in what used to be an auto truck, but I swapped all electronics with the engine and transmission. So now this is a 6 speed manual with the manual electronics. 🤔

How about the clock spring, or cruise swithces being different? The 99's and 02 are not identical in wiring. Just to add this the 01 and 02 auto trucks did not have the fly by wire, only the manuals did. 

You need to compare wire diagrams to see if there is a difference between the two as what was left in the truck and what you replaced.  Like @dripleysaid the controls like the brake peddle switch or switches' wiring my be off.

I’ll sure check this out, but it may take a few days to get back to it.  I’ll let you know what I find.  Thanks for all the info!

Need to swap back to all the 1999 Electronics to make it work. Fly by wire was later series function. So both the ECM and PCM need to be 2002. 

 

More on the swap.

 

 

53 minutes ago, Mopar1973Man said:

Need to swap back to all the 1999 Electronics to make it work. Fly by wire was later series function. So both the ECM and PCM need to be 2002. 

 

More on the swap.

 

 

He appears to have done that with the ECM and PCM plus harnesses I believe.