I'm not sure why there aren't dozens of reports about this, but the ABS sensor wires have been a recurring problem on the Aztek for a long time. When one of the sensor wires breaks due to flexing of the suspension, the ABS and AWD Disable warnings will illuminate, disabling both systems. The solution is to check each wheel, disconnect the ABS sensor one at a time, turn the ignition to the ON position, and check the voltage of the each pair of wires with a multi-meter until you find the one with no / low voltage. Once found, peel back the plastic wire loom and locate the broken wire. Either repair or replace that section.

Sometimes it will not be the wire at all, but instead the hub itself. You will know that this is the case if the voltages are good on all four wires. To find out which hub is bad, go back around and test the resistance on the hub side of those same connectors. When you find one that is shorted, open, or doesn't match closely to the others, you've located the problem hub. Replace that hub assembly. They are inexpensive and not too hard to replace with the proper tools.