2004 silverado 2500hd p2771 code

[Rem7mm870]

Before I get into it, I don't have the auto 4wd so no transfer case control module. Before the code had appeared the truck was acting strange. One day it would put itself into 4hi, another 2hi, then 4lo, then neutral. It would come out of it each time. So I put in a new encoder motor, now it won't illuminate the selector switch or do anything when I try to switch between gears and the code appeared. I have cleaned the chassis grounds on the frame and inspected the tcase housing for any pump rub out but I'm at a loss. Any help appreciated!

[Jsdirt]

Been a long time since I've dealt with this, but the encoder motor needs to be set in neutral if I'm not mistaken, AND the transfer case has to be in neutral as well - if they're not matched during installation, it won't work.

 

Based on your symptoms, it wasn't the encoder motor anyway. Hopefully you still have the original to put back in.

 

Sounds like a bad switch or wiring is shorting out intermittently - same as those buttons being pressed. If it's shifting, it's not the encoder motor. Hopefully you can get your money back on that.

[carkhz316]

On 2/17/2025 at 10:02 AM, Rem7mm870 said:

Before I get into it, I don't have the auto 4wd so no transfer case control module. Before the code had appeared the truck was acting strange. One day it would put itself into 4hi, another 2hi, then 4lo, then neutral. It would come out of it each time. So I put in a new encoder motor, now it won't illuminate the selector switch or do anything when I try to switch between gears and the code appeared. I have cleaned the chassis grounds on the frame and inspected the tcase housing for any pump rub out but I'm at a loss. Any help appreciated!

If you have a push button 4wd, you most certainly do have a transfer case control module. In either case, its because there is a wiring problem between the transfer case control module (if push button) or the TC itself (if manually shifted) that indicates to the PCM that you're in 4LO. Its a single wire, gray with black stripe, that is either broken or shorted.

Edited February 24, 2025 by carkhz316