Circuit Description
The front axle control circuit consists of an electric motor actuator which engages and disengages the front axle. The front axle actuator's motor 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 to it, a front axle feed circuit, front axle ground circuit, front axle control circuit, and a front axle switch circuit.
Whenever a shift to AUTO 4WD, 4HI, or 4LO is requested, the automatic transfer case control module engages the front axle by grounding the front axle control circuit through a current limiting driver.
This DTC detects a shorted actuator, or a short to 12 V on the Front Axle Control Circuit.
Conditions for Setting the DTC
| • | The system will try to engage the front axle. If it can not engage the front axle, the system will not attempt it again during that ignition cycle. |
| • | The transfer case shift control module reads back the front axle output as a high voltage when a low voltage is expected. |
Action Taken When the DTC Sets
| • | All shifting for 4WD and AUTO 4WD mode will be disabled. |
| • | SERVICE indicator (4WD/AWD) lamp will be latched on for the remainder of the current ignition cycle. |
Conditions for Clearing the DTC
| • | The transfer case shift control module will clear the DTC if the condition for setting the DTC no longer exists. |
| • | A history DTC will clear after 100 consecutive ignition cycle without a fault present. |
| • | History DTCs can be cleared using a scan tool. |
Test Description
The number(s) below refer to the step number(s) on the diagnostic table.
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Tests the operation of the front axle switch.
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Tests the electrical control of the front axle switch.
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Tests the Front Axle Control circuit for a short to voltage.
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Inspects for poor connections at the front axle switch/actuator.
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Inspects for poor connections at the harness connector of the transfer case shift control module.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Transfer Case Diagnostic System Check performed? | -- | Go to Step 2 | Go to Diagnostic System Check |
Does the front axle turn ON and OFF with each command? | -- | Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 3 | |
Does the test lamp turn ON and OFF with each command? | -- | Go to Step 5 | Go to Step 4 | |
Test the Front Axle Control circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Was the condition found and corrected? | -- | Go to Step 9 | Go to Step 6 | |
Inspect for poor connections at the front axle switch/actuator. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Was the condition found and corrected? | -- | Go to Step 9 | Go to Step 7 | |
Inspect for poor connections at the harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Was the condition found and corrected? | -- | Go to Step 9 | Go to Step 8 | |
7 | Replace the front axle switch/actuator. Refer to Electric Motor Actuator Replacement . Is the repair complete? | -- | Go to Step 9 | -- |
8 | Replace the transfer case shift control module. Refer to Transfer Case Shift Control Module Replacement . Is the repair complete? | -- | Go to Step 9 | -- |
9 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
