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 powertrain control module (PCM) or the transmission control module (TCM) controls the actuator with a negative duty cycle. The actuator controls the supply fluid to the pump inlet in the rear drive assembly. When the actuator is commanded OFF, the PCM/TCM will detect a high voltage. When the actuator is commanded ON, the PCM/TCM will detect a 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. If the PCM/TCM detects a voltage on the axle actuator circuit that is outside of the calibrated limits then the all-wheel drive (AWD) disable lamp illuminates.
Conditions for Running the All-Wheel Drive (AWD) Disable Fault
| • | The system voltage is 9-18 volts. |
| • | The engine speed is greater than 500 RPM for 5 seconds, and the engine is not in fuel shut-off. |
| • | The rear drive module must not be in an overtemperature condition. |
Conditions for Turning On the All-Wheel Drive (AWD) Disable Lamp
The AWD disable lamp illuminates when one of the following conditions exists for 5 seconds:
| • | The PCM/TCM commands the solenoid ON and the voltage feedback remains high, B+. |
| • | The PCM/TCM commands the solenoid OFF and the voltage feedback remains low, 0 volts. This condition is present for 3 key cycles. |
Action Taken When the All-Wheel Drive (AWD) Lamp Illuminates
| • | The PCM/TCM does not illuminate the malfunction indicator lamp (MIL). |
| • | The PCM/TCM inhibits AWD. |
Conditions for Clearing the All-Wheel Drive (AWD) Disable Fault
The PCM/TCM cancels the fault default actions when the fault no longer exists.
Important: When an AWD mini spare disable condition is present, after correcting the condition, the vehicle must be driven 0.5 km (0.3 mi) in a straight line and then brought to a complete stop before the PCM/TCM will command the AWD disable lamp OFF.
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 | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: All-Wheel Drive Schematics | ||||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |||||||
2 | Verify the fault is present. Does the system operate normally? | -- | Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 3 | ||||||
Does the voltage measure within the specified value? | 9-14 V | Go to Step 4 | Go to Step 7 | |||||||
Does the test lamp illuminate? | -- | Go to Step 5 | Go to Step 8 | |||||||
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 9 | Go to Step 6 | |||||||
Test the axle actuator control circuit for the following conditions:
Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 10 | |||||||
7 | Locate and repair an open or short to ground in the ignition 1 voltage circuit. Refer to Circuit Testing and Wiring Repairs . Did you complete the repair? | -- | Go to Step 11 | -- | ||||||
8 | Locate and repair an open in the ground circuit. Refer to Testing for Continuity and Wiring Repairs . Did you complete the repair? | -- | Go to Step 11 | -- | ||||||
9 | Replace the differential clutch pump actuator check valve. Refer to Differential Clutch Pump Check Valve Replacement . Did you complete the replacement? | -- | Go to Step 11 | -- | ||||||
10 | Replace the PCM for 3.5L or the TCM for 3.9L. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 11 | -- | ||||||
11 |
Does the fault set? | -- | Go to Step 3 | |||||||
