The front axle control circuit consists of an electric motor actuator which engages and disengages the front axle. The front axle actuator consists of a Permanent Magnetic (PM) motor, a worm gear controlled plunger, a front axle switch and an electronic control circuit all within the actuator assembly.
The front axle actuator has four circuits connected:
• | Ignition 3 voltage circuit |
• | Ground circuit |
• | Axle actuator control circuit |
• | Axle switch signal circuit |
Whenever a shift to 4HI, or 4LO is requested, the transfer case shift control module engages the front axle by grounding the axle actuator control circuit through a current limiting driver.
The numbers below refer to the step numbers on the diagnostic table.
This step tests the electrical function of the front axle actuator. Helps determine between mechanical and electrical malfunctions.
This step tests for proper power and ground at the front axle actuator.
This step tests the operation of the axle actuator control circuit.
This step tests the electrical function of the axle actuator control circuit.
This step tests for proper ignition 3 voltage to the front axle actuator.
This step tests for open fuse in the ignition 3 voltage circuit.
This step tests the axle actuator control circuit for an open or high resistance.
This step tests the axle switch signal circuit for an open or high resistance.
This step helps determine if the front axle actuator has a mechanical malfunction.
This step tests the axle switch signal circuit for a short to voltage.
Inspect the front axle for a mechanical malfunction.
Step | Action | Value(s) | Yes | No |
---|---|---|---|---|
Schematic Reference: Transfer Case Control Schematics | ||||
1 | Was the Transfer Case Diagnostic System Check performed? | -- | Go to Step 2 | |
Does the scan tool display the Front Axle Switch status as Locked? | -- | Go to Step 10 | Go to Step 3 | |
Does the voltage measure within the specified values? | 9-14 V | Go to Step 4 | Go to Step 6 | |
Does the test lamp illuminate? | -- | Go to Step 5 | Go to Step 8 | |
Does the scan tool display the Front Axle Switch status Locked? | -- | Go to Step 15 | Go to Step 9 | |
Measure the voltage between the ignition 3 voltage circuit and ground. Does the voltage measure within the specified values? | 9-14 V | Go to Step 13 | Go to Step 7 | |
Test for open fuse in the ignition 3 voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 14 | |
Test the axle actuator control circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 16 | |
Test the axle switch signal circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 16 | |
Does the scan tool display the Front Axle Switch status Locked? | -- | Go to Step 11 | Go to Step 12 | |
Test the axle switch signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 16 | |
Inspect the front axle for a mechanical malfunction. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 16 | |
13 | Repair an open in the ground circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 17 | -- |
14 | Repair an open in the ignition 3 voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 17 | -- |
15 | Replace the front axle actuator. Refer to the Electric Motor Actuator Replacement . Did you complete the replacement? | -- | Go to Step 17 | -- |
16 | Replace the transfer case shift control module. Refer to the Transfer Case Shift Control Module Replacement . Did you complete the replacement? | -- | Go to Step 17 | -- |
17 |
Does the symptom re-occur? | -- | Go to Step 2 | System OK |