8.1L PCM Controlling 1991 to 93 4L80E

[1BadAction]

Is this possible? In other words, if I take an 8.1L power plant with it's PCM and swap it into an older 3/4 ton Suburban that originally came with a 4L80E, can that 8.1L PCM control the older 4L80E? Or will I need to swap something out in the transmission?

[slow67]

It depends. If the 8.1L had a 4L80E behind, obviously yes. If the PCM had an Allison, but has the same OS number as a tune that had a 4L80E, then yes, do a segment swap. Also, if the 4L80E has the original style (91-92) internal harness, it will need to be updated. If its an 04+ PCM, will probably need an 04+ force motor in the 4L80E.

[1BadAction]

Excellent, IF I do what I'm thinking, I want to make sure I start with the easiest engine/pcm to use. Sounds like up to an 03 is the way to go.

I'm not sure if the harness has been done, but from what I understand it's a fairly simple procedure. Project TowBeast full steam ahead! lol