Circuit Description
The differential clutch pump actuator check valve assembly is a pulse width modulated actuator mounted to the rear drive assembly. Ignition voltage is supplied to the clutch pump actuator check valve through a fused circuit. The PCM controls the actuator with a negative duty cycle. The actuator controls the fluid supply to the pump inlet in the rear drive assembly. When the actuator is commanded OFF, the PCM detects high voltage. When the actuator is commanded ON, the PCM detects low voltage. At engine start-up, the actuator is turned ON at 49-90 percent duty cycle for 3 seconds, then drops to 16-28 percent for holding. Every 30 seconds, the duty cycle is ramped to 49-90 percent for 0.5 second, then back to 16-28 percent.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This step tests the ignition 1 voltage circuit for proper voltage.
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This step tests the ground circuit for an open.
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This step tests the axle actuator control circuit duty cycle.
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This step tests the axle actuator control circuit for an open or short.
Step | Action | Values | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
Schematic Reference: Differential Lock Schematics | ||||||||
1 | Did you perform the Diagnostic System Check - Rear Axle Controls? | -- | Go to Step 2 | Go to Diagnostic System Check - Locking/Limited Slip Rear Axle | ||||
2 | Verify the fault is present. Does the system operate normally? | -- | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 | ||||
Does the voltage measure within the specified value? | 9-14 V | Go to Step 4 | Go to Step 8 | |||||
Does the test lamp illuminate? | -- | Go to Step 5 | Go to Step 9 | |||||
Important: The differential clutch pump actuator check valve duty cycle will initiate at 49-90 percent duty cycle for 3 seconds, then drop to 16-28 percent duty cycle. Every 30 seconds, the duty cycle will cycle up to 49-90 percent for 0.5 seconds, then back to 16-28 percent. Is the duty cycle functioning as described? | HI Range: 49-90% LO Range: 16-28% | Go to Step 10 | Go to Step 6 | |||||
Test the axle actuator control circuit for an open, short to voltage, or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 7 | |||||
7 | Verify that the differential clutch pump actuator check valve connector is securely fastened. Using a scan tool, check the status of the following conditions:
Did you find and correct the conditions? | -- | Go to Step 12 | Go to Step 11 | ||||
8 | Locate and repair an open, or a short to ground in the ignition 1 voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 12 | -- | ||||
9 | Locate and repair an open in the ground circuit. Refer to Testing for Continuity and Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 12 | -- | ||||
10 | Replace the differential clutch pump actuator check valve. Refer to Differential Clutch Pump Check Valve Replacement Did you complete the replacement? | -- | Go to Step 12 | -- | ||||
11 | Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls - 3.4L. Did you complete the replacement? | -- | Go to Step 12 | -- | ||||
12 | Turn the ignition ON, with the engine OFF. With the differential clutch pump actuator check valve removed, command the valve ON, then OFF. Refer to Differential Clutch Pump Check Valve Replacement Does the differential clutch pump actuator check valve move within the listed parameters? | 2 mm | Go to Step 13 | Go to Step 3 | ||||
13 | Does the AWD system operate normally? | -- | System OK | |||||
