Hi y'all. I have a 2011 express 3500 cargo vin 'G' (6.0 flex) van and since i bought it 3 years ago i've had intermittent limp mode. I'll be driving, or idling, and the van will display reduced power mode, service stabilitrak, service tcm, service abs. There is 0 response from the engine at any amount of throttle applied when it goes into limp mode. Its shows 4 codes:
C0242 (TCM MALFUNCTION)
P0573 (CRUISE/BRAKE SW "A" CIRCUIT HIGH)
P1516 (TAC MODULE, POSITION)
P2101 (THROTTLE ACTUATOR "A" CIR)
this vehicle did have lojack spliced into a bulkhead connector near the parking brake, could these wires be causing this issue? I just cleaned up what I'm assuming is my ecbm ground ( drivers side front of frame rail near door hinge. Im fairly confident it is a wiring fault, i however do not know how to navigate this forum yet.
To any and all that drop a line much thanks in advance.

Edit: If anyone knows where a wiring schematic for the afflicted sensors/ actuators would be i'd greatly appreciate the hand up. Im prerty sure it'd have to be a power or ground thats common to the foot controls considering the codes. I also dont know where the TCM is located so it may be in he same reigon and thus yet another common wire. The wire colors look to be Red with white its either a ln 18ga or 20ga wire as well as a pink, i believe to be a switched ignition wire. Currently poking around under the dash investigating the wires the former owner spliced. Could the wires be twisted cause a less than optimal connection in the bulkhead?

 

BBB Industries- Premium Alternators, Starters, Power Steering Products and Turbochargers | TSB and Wiring Diagrams Database

and

https://www.gmupfitter.com/pages/body-builder-manuals

My TCM is mounted to the side wall all the way over on the passenger side under the hood. But the upfitter electrical manuals should tell you where yours is.

 

Re: mountainmanjoe
Thanks for the links, they'll be invaluable i'm sure.

 

Talked to a tuner he said the codes likely started at the throttle body, checked it, its borderline out of range. So got an AC Delco one on its way, will update if that fixes it. I know most of the forum with similar fault codes present point that direction... There are however the few lemons out there, don't recall the post but someone else put every part in it shy of the ecm and a harness and i dont have the time or money to swing that so fingers crossed.

 

All my wires appear to be intact point to point.

 

Turns out the throttle actuator motor in the throttle body was worn out, very common issue apparently in all of GM throttle by wire vehicles.