‘03 LB7 Limp Mode

[Bigshankhank]

Helping a friend diagnose his Duramax. Approx 180k miles, he bought the truck at 110 and the PO stated that he had replaced all the injectors recently. Highway driving, not towing, engine started running rough and CEL illuminated and speed dropped below 30.
Codes P-0201, 0204, 0206, 0207, 0700, and 2146 all came up.
I have read some of the threads on here about limp mode but they all seem to relate specifically to the ‘01 LB7. I also reached out to John Kennedy for some advice, but any thoughts here?

[DmaxMaverick]

With all the injector control circuit codes across both banks, I'd suspect a harness or connector issue first. Check all the under hood connectors. A loose connector or bent pin(s) will cause all kinds of havoc. The P0700 code is only the TCM commanding the MIL. You'll need a more capable scanner to read the actual tranny code, but I suspect it's likely a complaint due to the rough running. Chase any tranny issue after the engine is where it should be.

[DmaxMaverick]

Also check the battery health, terminals and connections. Poor voltage management can cause issues with the injector driver and tranny.

[More Power]

Go to: https://www.thedieselpage.com/#search

Enter P2146 in the search box.

Best info ever...

[Bigshankhank]

Excellent info, thank you. My buddy is a charter boat captain and has both a lot more wiring experience than I do as well as a lot more free time, so he is going through the harness and connections and testing circuits and grounds, so it sounds like he should be able to find it.