2003 GMC K2500HD Questions

David89GMC · September 18, 2019

Hello Folks.

I'm new here, because I just bought a 2003 GMC K2500HD. This truck was originally a Fire Captain's Truck with a roof antenna and coax for the radio, what looks like a light bar socket on the roof. It also has a goose neck hitch in the bed, and a front winch bumper. Anybody want an ugly black winch bumper?

I have a couple of questions.

First, the truck has a $20 Walmart special radio that doesn't work, so I'll be replacing that with something good. The horn doesn't work either... There is no RPO code that specifies a Bose audio system, or OnStar, although the full complement of steering wheel buttons are present. I'd like to use the buttons to control the new radio.

Second, I found a new key fob online, so that's good to go, but what about the actual door and ignition keys? Is the ignition key "normal" or does it have a chip inside it?

Third, the transfer case was just replaced by the previous owner, but it doesn't have a New Venture tag on it. How can I be sure it's an NV263? Are there casting numbers, or since it works fine on this truck it must be correct?

Thanks a bunch.

davester · September 18, 2019

The round tag is it for identification of the transfer case. You should have a NP263HD (1500's got the NP263, 2500's w 6.0 go NP263HD, diesels got the NP263XHD, not sure what the 8.1L's got). Some parts are shared, some are different (in particular, the chain and sprockets), input shaft and rear output shaft size/spline count also varies with application, not sure about the front.

Don't know about your truck, but mine doesn't need a special key ('04 Sierra cab&chassis).

As for the radio, first see if they hacked up your wiring harness. Hopefully, they didn't, then you can get a wiring harness adapter that just plugs into the truck's harness, and that provides support for:

-retained accessory power (RAP)

-chimes

-steering wheel controls (SWC)

-reverse signal for rear camera if you want

-parking brake signal for radio if it supports playing video

-enough power for your radio (in particular, if the radio has USB ports, it needs a bunch of amps for that)