This question probably stems from my lack of understanding on how PCM and OS swaps work, and the fact that I’m used to the GTO where it seems touching anything ECM or BCM related is a nightmare, but here goes.

I have a 2007.5 silverado and want to swap the stock 5.3L without VVT (E38 PCM & 4l60e) with an L92 w/ VVT out of a 2008 Yukon Denali also with (E38 PCM, but with a 6l80e). I would really like to keep the VVT. I have access to the harness and PCM from the Denali, but I'm not sure if that actually helps at all.

Harness:

I don’t think I can use the Denali harness without a lot of work because the Denali harness does not have an external TCM it ties into – feels like if I went that route, I’d be better off trying to bring the 6l80e along for the ride. It seems like there should just be a way to run wires directly from the VVT connector to the ECM? Has anyone ever done this?

ECM:

If I swap the ECM from the Denali in my garage, I’m assuming the BCM or TCM will puke and the truck won’t run due to security features and/or transmission incompatibility. At a minimum, I think this means finding a friendly dealer and paying for a tow there to get everything talking together. I really don't like the idea of doing this because then if I've screwed up the wiring, I've got to tow it home, try to fix it, tow back to the dealer, etc...

Alternatively, I think I could try swapping a Denali OS onto my E38, but I swear I’ve read that this can cause problem. Some people say that swapping among 07-08 and 09-10 is okay, but that you can’t mix them (either for the ECM OS or the TCM’s) without bricking. I'm also still not sure if this changes how the PCM talks to the truck BCM or TCM and will cause problems or not.

Any thoughts on how best to do this?