L92 - LS3 Harness Hookup / Modifications

Over the next several months the plan is to install an L92 (with V V T but no AFM/DOD) engine which was picked up last year. This is a 6.2L Escalade/Denali motor that's now getting an LS3 intake & L99 water pump along with a new set of OEM LS3 hollow stem (lightweight) intake valves. The 07 donor vehicle met its demise in early 08 & after careful inspection we assume the engine has less than 10k miles logged (since carfax shows nothing more than 46 miles when a title was issued).

A good deal of time was spent researching the L92 engine harness (stock GM) and the aftermarket fuse/relay block…documenting everything found in many GM schematics…all of which went into a continuously growing spreadsheet we’ll use to connect it all together. Hopefully the document will help those working with a e38 PCM/ECM now...as the project slowly moves forward.

As the GM cruise control is part of the plan, an E38 ECM and BCM (Body Control Module) was needed (along with the BCM's 7 plug in mini-harnesses). And since we’re adding the BCM, we decided to take advantage of its serial data Power Mode Master function which activates relays and other outputs of the PMM as needed. This determines the required mode such as: Off, Accessory, Run, Crank Request…to control various relays, modules, etc. Also, for its Electric Power Management (improving battery life & gas mileage) as well as for the GMLAN gateway (both the high & low speed LANs) to the Data Link Connector (no more Class 2 modules) for reporting codes and programming updates. Some folks may want to add traction and launch control modules which, I guess, could be a possibility. The emissions related connectors were removed and many unwanted diagnostic trouble codes will need to be programmed out.

Don’t expect many updates to the spreadsheet anytime soon since it will be a few months before the modified harness is mated to the new fuse/relay block mounted under the hood & the wiring cut to size during the final install.

Here’s the .mht file link that should launch the document in your browser.

And the .pdf file link we’ll be using to print on 3-hole paper, stick in a binder and work from it.

Don't spend a lot of time messing with the cruise control part of the wiring, The factory Porsche system is a stand alone item and as long as it get a speed signal from the tranny it will work.

Very Nice! I wish i would have been that detailed in my wiring.

Mark