Electronic 4X4 not working?

TOBYFARM1234567

MEMBER
2008 GMC SIERRA
5.3L
V8
4WD
AUTOMATIC
245,000 MILES

I have an electronic 4wheel drive. When I turn the switch to engage 4x4 it blinks orange light for about 30 seconds then quits but always stays in 2wd. I have replaced shift position sensor, actuator on the front differential cleaned the ground wire on body mount. Replaced shift motor on the transfer case, replaced the transfer case and replaced the switch an TCCM and had that reprogrammed by gm dealer. Checked fuses have power to everything just will not engage keeps blinking. There is no "service 4wheel drive" showing on the dash. Any advice?

1 Reply

JACOBANDNICKOLAS

MECHANIC
109,709 POSTS

Hi,

This could be the result of a few things. You have done a lot already. I assume power/fuses are good and there are no wiring issues, correct?

Here is what I suggest: We need to scan the can-bus to see if there are codes stored. Otherwise, it becomes a guessing game.

CAN stands for controller area network. Basically, the different modules are tied together via a few wires. This type of scan will retrieve codes regardless of the module storing them.

Here is a link that explains how it's done:

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

Let me know if that is something you can have done or do yourself.

Take care,

Joe