Which wires need to be added for lb7 to lbz conversion?

[Rick Henderson]

We just installed a 2006 LBZ into a 2003 LB7 and needed to add a couple of wires for the scanner to work. Does anyone know which 2 wires to add to the DLC (obd port) for the high speed GMLAN data bus, and another wire for the "driver shift request" signal going to the TCM (signal for the tap-shift)?

FYI: the engine, allison 6 speed, wiring harness, ecm, tcm are all swapped over. The truck runs, but in limp mode. It shows reduced engine power and idles around 1000rpm.

Thanks,
Rick

[More Power]

I don't have a set of the new wiring diagrams, but I'd be curious how much of the underdash wiring you upgraded along with the engine and ECM/TCM.

We get a few questions from time to time about the sort of swap you've done. Let us know a little more about your swap.

Jim

[Rick Henderson]

Jim,
I didn't have to change any of the wiring under the dash just in the engine compartment. I did hear that I need to add a couple of wires.

Its running... but is in limp mode as I think the 2003 transfer case maybe different than the 06. The 06 transfer case has manual shift 4x4 and my truck came with push button shift. I was hoping someone was knowledgeable enough about this conversion to chime in.

[More Power]

Jim,
I didn't have to change any of the wiring under the dash just in the engine compartment. I did hear that I need to add a couple of wires.

Its running... but is in limp mode as I think the 2003 transfer case maybe different than the 06. The 06 transfer case has manual shift 4x4 and my truck came with push button shift. I was hoping someone was knowledgeable enough about this conversion to chime in.

Your truck still has the TCCM (Transfer Case Control Module), but you can remove it (it's worth about $100-200). If you're using the 2006 ECM/TCM, the electronics shouldn't be looking for the TCCM.

In the past, I've visited the local GMC dealer, and they would print a wiring diagram for me for special projects. Even the parts counter guy has access to the system and can print documents. I'd ask if they would print you a page showing the data port (ALDL) pinouts. Getting access to the data will help you troubleshoot this problem.

A last resort might be to install a 2006 in-cab harness...

Jim

[Rick Henderson]

I joined alldata and printed the schematics. I tried the dealer and they are somewhat helpful and want to see the conversion after its done.

This afternoon, I was able to get the DLC to read codes on the tool right before I had to leave. Now I have to decipher which one for the tap shift.