2000 GMC Sierra four wheel drive

RICM

MEMBER
2000 GMC SIERRA
V8
4WD
AUTOMATIC
260,000 MILES

I have replaced both motors for the four wheel drive system. With all wheels off the ground, all wheels will spin. When I have all wheels on the ground the front wheels do not work. All lights flash when I press the buttons and then stay on as if all systems are working.

What direction should I be looking?

Thanks

Ric Miller

1 Reply

BRIAN 1

MECHANIC
1,030 POSTS

Turn the ignition ON, with the engine OFF.
Install a scan tool.
Use the scan tool in order to read the Front Axle Switch Status.
Does the scan tool display the Front Axle Switch status as Locked?
--
Go to Step 4
Go to Step 3

3
Use the scan tool in order to read the Commanded Mode Indicator status.

Is the transfer case in Auto 4WD, 4WD HI, 4WD Low mode?
--
Go to Front Axle Will Not Engage
Go to Step 5

4
Use the scan tool in order to read the Encoder Gear Position status.

Is the transfer case in 2WD mode?
--
Go to Front Axle Will Not Disengage
Go to Step 5

5
Replace the transfer case shift control module. Refer to the Transfer Case Shift Control Module Replacement.

Is the repair complete?
--
Go to Step 6
--

6
Use the scan tool in order to clear the DTCs.

Before you do anything I would have it scanned for any transfer case codes, then post the code. Also the 4WD mode switch was a common problem on these. But I would start with the above first.