The AWD lock will only work up til approximately 7mph and then is programmed to turn off after that. It's primary purpose it to get you unstuck from a sitting position. You will see the AWD indicator light turn off once you're up to speed. If, however, while you're driving and your MO sense slippage, it will automatically engage AWD. You may not know it though as the AWD light does not turn on during that situation. If it does turn on, it is because it is warning you that there is a problem with your AWD, not that your AWD is working. So be happy that you don't see it lit while driving. The MO's AWD system is not meant to stay on permanantly as it is not designed strong enough for it. It's better than you don't use your AWD lock if not needed as it could later cause major failure with your transfer case. Repair costs....$6000 or more if you don't have a warranty.
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Hi! Matt, Most likely if the anti-lock brake light and the awd disable light come on at the same time a wheel bearing / wheel speed sensor assembly is faulty.Listen for a humming noise when driving and try to determine where it is coming from(left/right/front/ back) or any looseness/play in any wheel. That's the possible bearing/wheel speed sensor causing the problem. Or have the abs system scanned to determine which wheel sensor is reading incorrectly.If the awd disable light is off then the awd system should be funtioning.
The vehicle is always in AWD and that cannot be altered . There is a 3rd diff in the gear box that allows independent operation of the front and rear wheels to prevent drive line wind up . When you select 4WD you lock up that 3rd diff so that both front and rear axles have to turn. This results in drive line torque wind up so the vehicle must not be driven in this mode on hard surfaces as there is no means for the wheels to slip and relieve the torque wind up . To loose the wind up reverse for several yards and any actuators that are trying to move will be able to or drive on slippery surfaces to allow the wheels to slip
3rd dealer stated that the problem was in the differential pump valve, when the temperture sensor was giving a false reading and disconnecting the rear wheel drive. Replaced with GM Part 88896067, and it solved the problem. Mechanic stated that if it is ONLY the AWD light, then this is usually the problem. If the ABS Disable light also goes on, then it is the harness on the wheel sensor.
This light is telling you that a problem exists in the AWD system, the light reset's everytime the key is turned off, then because the system fault s still there it comes back on, the 20 second delay is the time required for the system to test itself.