2005 Chevrolet Silverado 1500.
Dash lights = service 4 wheel drive
Question = service 4 wheel drive light comes on & push buttons won't shift into 4 wheel drive.
Answer: Well, there are a actually a few things that can cause this.

A faulty 4wd selector switch. (The switch you press with the lights).
A bad control module. It is located in the dash behind the headlight switch. A bad encoder motor. This is on the transfer case.
A scan of the 4wd module is needed to check for any fault codes.
2002  Silverado 25000 6.0L V8 Vortec.
Question = Where is the MAP sensor on a 6.0 Vortec V-8?
Answer: It is located right on top of the intake manifold, closer to the rear of the engine. It will have a 3 wire connector on it. You will have to remove the plastic cover that is over the intake manifold to access it. Very easy to locate and change if needed. Lubricate the new sensor's rubber boot lightly with some lithium grease or silicone to ease installation and provide a good seal.
1999 Chevy Silverado 4x4 5.3 Vortec.
Repairs for this problem = installed new transfer case, need new encoder motor.
Question = I replaced the transfer case due to burnt out clutches. Found the encoder motor to be seized. I replaced the encoder motor, and it tried to work and then burnt itself out, has internal open on the A/B motor circuit. Diagnosed as needing a new ATC module and encoder motor. Will not have parts in for a while. Wanting to know if truck will drive with encoder motor removed and front drive shaft removed.
Yes, you can drive the truck with the encoder motor off and/or the front driveshaft out of the vehicle. One thing you may you want to try, is manually shifting the transfer into two wheel drive by turning the fork with pliers or comparable tool. This won't do any damage and then you could even reinstall the drive shaft just to be safe. Either way would be fine, just keep an eye for fluid leaks or debris getting in the sensitive areas of the transfer case.
Chevy Silverado Four Wheel Drive Not Working

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