2000 GMC Sierra four wheel drive

2000 GMC SIERRA
260,000 MILES • V8 • 4WD • AUTOMATIC
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RICM
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  • 1 POST
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
Jul 19, 2009 at 4:50 PM
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BRIAN 1
  • CAR REPAIR CONTRIBUTOR
  • 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?
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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?
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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?
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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?
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Go to Step 6
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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.
Jul 20, 2009 at 6:22 PM
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.