NEED HELP After putting in new rebuild 4.2 Envoy can't get it to start up.

[Tboy4u2nv]

After I had put the engine back in the truck. I plugged all he wires back and wires to the starter back .and there's to plugs ends wires I don't know where they go. What is am missing

 

[Blckshdw]

Could you take a pic or 2 of what you're looking at? That would be a big help for us to know what you're seeing, and how to identify what you've got in front of you. Thanks

 

[mrrsm]

Some Requisite Information:

(1) Year, Make and Model of Your Original SUV?
(2) Year, Make and Model of the Engine DONOR Vehicle?
(3) Did the Swap Engine also include the DONOR PCM and Engine Bay Harness?
(4) What is the Source of the DONOR Engine? (Private Owner, Salvage, Wrecker)
(5) Was the DONOR Engine Running prior to its R&R from the DONOR SUV?
(6) What if any Engine Prep did You Perform upon the DONOR Engine?

 

[Mooseman]

He did say it's a rebuilt but we need the above info. There have been instances of people putting in the wrong engine. 08-09 engines WILL NOT work in the older trucks nor will an older engine in an 08-09.

 

[paul2005tb]

He did say it's a rebuilt but we need the above info. There have been instances of people putting in the wrong engine. 08-09 engines WILL NOT work in the older trucks nor will an older engine in an 08-09.

Hard to understand how the PCM was changed that significantly in 08.

 

[Mooseman]

4.2L interchangeability by years
4.2L Incompatibility by years ('04 engine in '08 truck, no start)

The 08-09 engine changed internally to a 58x crank reluctor whereas the older ones were 7x. Subsequently the PCM changed with it.

 

[mrrsm]

...and... "Apples vs. Oranges" Due to having Two Completely Different PCMs and Harnesses:

Delphi Model P10 PCM for Early Model GMT360 PCMs have Three Symmetrical Connectors:



Delphi Model P12 PCM for Later Model GMT-360s has Three Asymmetric Connectors:

 

[azswiss]

Here's an old thread discussing interchangeability issues:

What years are interchangeable on the I6 4.2 engine?