Gear indicator issue

[Andrew8335]

Before we get into detail I’ll mention the truck is a 2003 Silverado 2500hd with the lb7 (Duramax/allison1000) So a few months back I wrecked my truck pretty badly. Wrapped it around a pole however upon further inspection it caused no frame damage. A friend of mine was parting out a 2003 gmc 1500 so I figured I’d cab swap it, got the cab from him for $650 and took two afternoons and swapped them out. Everything went great I’m just having one tiny issue that is electronic I’m hoping someone on this great website can give me some good insight as to what I can do about it. So I get no indication on the dash from the gear indicator. The truck will only start if the lever is in park. But still no indication in the dash I also do not have reverse lights. I’m assuming the whole reason I’m having this issue is because the cab came off of a 1500 with a 5.3 and 4l60e and got placed on my frame with my Duramax and Allison transmission. And the wiring for the Allison is obviously not the same as the 4l60e. Any help is greatly appreciated! 

[davester]

Did you swap the wiring & computers in the cab and use the ones from the LB7?

[Andrew8335]

6 hours ago, davester said:

Did you swap the wiring & computers in the cab and use the ones from the LB7?

No, the only thing I changed was the transfer case module. And there is an easier way around it aside from swapping the entire cab harness.

[davester]

It's my understanding (from following some threads on people making Duraburbs) that the harness, at least between the bcm and the pcm, is different between the different engines (6.0/8.1/diesel), and that they got it to work by carefully comparing wiring diagrams and pinouts between the two vehicles, and some trial and error, and got it to work.  You may be able to compare wiring diagrams to modify your cab's harness to work right with the new engine, but I think it's at least more straightforward, and possibly easier to just swap the wiring harness and computer, particularly if the harness didn't get damaged in the accident.

[Andrew8335]

7 hours ago, davester said:

It's my understanding (from following some threads on people making Duraburbs) that the harness, at least between the bcm and the pcm, is different between the different engines (6.0/8.1/diesel), and that they got it to work by carefully comparing wiring diagrams and pinouts between the two vehicles, and some trial and error, and got it to work.  You may be able to compare wiring diagrams to modify your cab's harness to work right with the new engine, but I think it's at least more straightforward, and possibly easier to just swap the wiring harness and computer, particularly if the harness didn't get damaged in the accident.

I’ll have to compare some diagrams and see what I find. Appreciate your info! Anything helps