I am still a long way from firing up my 8.1L in my rock crawler and I would like to test and scan the PCM I just purchased before it gets too late to complain about it.

The 8.1L is using the blue / green harness from a 2005 Avalanche w/ 4L80E
I have the pinout diagram for the harness, and I have the pin out diagram for the OBDII connector.

What I am missing is the connection between the two?

Can I put temporary power and ground on the harness and test the PCM with HPTuners?

Thanks.

 

yes you can supply battery power to both the battery connections and the ign pins along with the earths ... then plug into the diagnostic plug with HP's and all should be sweet... as the loom been setup as a standalone loom???

you just need to make sure that the bench harness has earth on pin 4,5 batt on pin 16 and the serial data on pin 2

 

I have not reworked the harness yet, but I think I have found all the diagrams I need to do that, except the interconnect for the OBDII.

All I have is the engine harness, I do not have the dash harness or the OBDII pigtail yet. I still need to make a trip to the junkyard.

 

ok... yes well once you have a ODB2 plug you can bench test the pcm... i have a pcm bench test harness that i can plug all sorts of ECU's in.. very handy.. so it can be done.... if you need any more help when the time comes let us know

 

I have all the bench top stuff too if you need a hand or help with the OEM harness. Also should have a few spare OBD2 connectors laying around if you need one.

An 8.1 powered rig?! I'd love to check that out. Any pics of progress? Hell my little 5.3 will idle over most obstacles Where do you wheel at?

 

Found it!

https://ls1tech.com/forums/conversio...cm-obd-ii.html

Here the latest pic. Working on the front clip, radiator, fluid coolers, harness, PCM mount, etc. Working toward the back before I pull the body and finish welding the underside of the frame.

We ride Gray Rock and Morris Mountain mostly. I have been to Tellico (before they closed it), Mont Eagle, TN and Windrock, TN. It's been too long though. I need to get this one going!!

 

yep those pinouts are correct.. easy as

 

Awesome project man.. We're from MD area and a bunch of us from the local club are getting ready to take a long wheeling trip to AL, SC.. Going to hit Mountain Side, Choccolocco Mountain, Morris Mountain, and Gulches between June 20th-27th.