Four-Wheel Drive Does Not Engage

Four-Wheel Drive Does Not Engage

Circuit Description
The front axle control circuit consists of an electric motor actuator which engages and disengages the front axle. The front axle actuator consists of the following components within the actuator assembly:
^ A permanent magnetic (PM) motor
^ A worm gear controlled plunger
^ A front axle switch
^ An electronic control circuit

The front axle actuator consists of the following circuits:
^ An ignition 3 voltage circuit
^ A ground circuit
^ An axle actuator control circuit
^ An axle switch signal circuit.

Whenever a shift to 4WD is selected, the transfer case switch engages the front axle by grounding the axle actuator control circuit.

Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. Tests for proper ignition 3 voltage to the front axle actuator.
3. Tests for proper ground at the front axle actuator.
4. Tests for proper ground at the axle actuator control circuit through the transfer case switch.
5. Tests the transfer case switch ground circuit for an open.
6. Tests the transfer case switch for proper operation.

Step 1 - Step 7:

Step 8 - Step 13:

Four-Wheel Drive Does Not Engage