Circuit/System 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 DTC
| • | 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 over temperature condition. |
Conditions for Setting the DTC
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. |
| • | The PCM/TCM detects fluid temp is too high. |
Action Taken When the DTC Sets
| • | The PCM/TCM does not illuminate the malfunction indicator lamp (MIL). |
| • | The PCM/TCM inhibits AWD. |
| • | The PCM/TCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM/TCM stores this information as Failure Records. |
| • | The PCM/TCM stores the AWD disable fault in PCM/TCM history. |
Conditions for Clearing the DTC
| • | A scan tool can clear the fault. |
| • | The PCM/TCM clears the fault from PCM/TCM history if the vehicle completes 40 warm-up cycles without a non-emission related diagnostic fault occurring. |
| • | The PCM/TCM cancels the fault default actions when the fault no longer exists. |
Diagnostic Aids
| • | An ABS DTC may cause the AWD Disabled light to illuminate. Check for ABS DTCs if no AWD fault is present. |
| • | The AWD data list can be used to assist in determining which type of fault is causing the AWD Disabled Lamp to illuminate. |
Reference Information
Schematic Reference
All-Wheel Drive Schematics
Connector End View Reference
Rear Axle Connector End Views
Description and Operation
Locking Differential Description and Operation
Electrical Information Reference
Scan Tool Reference
Circuit/System Verification
AWD Data List
Parameter
| Specification
|
AWD Duty Cycle
| HI Range: 49-90% LO Range: 16-28%
|
AWD Circuit Status
| OK
|
AWD Fluid Temp. Disabled
| No
|
AWD Overtemp. Delay
| No
|
AWD Clutch Temp Disabled
| No
|
AWD Wheel Speed Disabled
| No
|
AWD Voltage Disabled
| No
|
AWD Minispare Disabled
| No
|
AWD ABS Disabled
| No
|
AWD Disabled
| No
|
AWD Last Disabled Reason
| None
|
- With a scan tool, verify the above data displays are within specification.
| ⇒ | If all parameters are within specification, refer to Circuit/System Testing -- All-Wheel Drive Disabled Indicator Malfunction. |
| ⇒ | AWD temperature disables can be caused by an open circuit.
If any parameter is not with specification, refer to Circuit/System Testing -- Differential Clutch Pump Actuator Check Valve Malfunction. |
- Using a scan tool, select the Body - Instrument Panel Cluster - Special Functions - Lamp Test mode.
- In the Lamp Test mode you can turn on or off the instrument panel indicators. All indicators will turn ON when commanded on and OFF when commanded off. The AWD DISABLE indicator should turn on or off as commanded.
Circuit/System Testing
All-Wheel Drive Disabled Indicator Malfunction
- Test the AWD Fuse in the Underhood Fuse Block. It should test NORMAL.
| ⇒ | If the fuse is OPEN replace the fuse. If the fuse OPEN’s again check the AWD Ignition 1 Voltage circuit for a short to ground. If the circuit tests normal, replace the Differential Clutch Pump Actuator Check Valve. |
- Ignition ON, engine OFF. Disconnect the connector at the Differential Clutch Pump Actuator Check Valve. Measure the voltage between the AWD Ignition 1 Voltage circuit, Clutch Pump Actuator Check Valve Connector pin C, and a known good ground. The
voltage should read B+.
| ⇒ | If the voltage reads less than B+ repair the OPEN/HIGH RESISTANCE condition in the AWD Ignition 1 Voltage circuit for an OPEN/HIGH RESISTANCE condition. |
- Measure the voltage between the AWD Ignition 1 Voltage circuit, Clutch Pump Actuator Check Valve Connector pin C, and the AWD hard ground circuit, Clutch Pump Actuator Check Valve Connector pin B. The voltage should read B+.
| ⇒ | If the voltage reads less than B+ check the repair the OPEN/HIGH RESISTANCE condition in the AWD hard ground circuit. |
Important: The AWD Axle Actuator Control circuit is a modulated ground, with a duty cycle of 16-28 percent in the LOW range and 49-90 percent in the HI range. As such a test lamp will not work properly
on it.
- Measure the voltage between the AWD Ignition 1 Voltage circuit, Clutch Pump Actuator Check Valve Connector pin C, and the AWD Axle Actuator Control circuit, Clutch Pump Actuator Check Valve Connector pin A. The voltage should read B+.
| ⇒ | If the voltage reads less than B+ test the AWD Axle Actuator Control circuit for an OPEN/HIGH RESISTANCE condition. |
- Ignition OFF. Measure the voltage between the AWD Ignition 1 Voltage circuit, Clutch Pump Actuator Check Valve Connector pin C, and the AWD Axle Actuator Control circuit, Clutch Pump Actuator Check Valve Connector pin A. The voltage should read 0 volts.
| ⇒ | If the voltage reads greater than 0 volts test the AWD Axle Actuator Control circuit for a short to ground. |
- With the connector connected, connect a DMM in parallel to the control circuit. Set the DMM to read duty cycle.
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.
- Engine running. Observe AWD Duty Cycle on the DMM from the time of engine start. Is the duty cycle functioning as described?
| ⇒ | If the duty cycle differs from that described, replace the Powertrain Control Module. |
- If all circuits and connections test normal, replace the Differential Clutch Pump Actuator Check Valve.
Differential Clutch Pump Actuator Check Valve Malfunction
- Ignition OFF, disconnect the harness connector at the differential clutch pump actuator check valve.
- Test for less than 1 ohm of resistance between the ground circuit terminal B and ground.
| ⇒ | If greater then the specified range, test the ground circuit for an open/high resistance. |
- Ignition ON, test for B+ between the ignition 1 voltage circuit terminal C and ground.
| ⇒ | If not the specified value, test the ignition 1 voltage circuit for a short to ground or an open/high resistance. |
- Connect a test lamp between the axel actuator control circuit terminal A and the ground circuit terminal C.
- With a scan tool, command the All Wheel Drive Solenoid ON and OFF. The test lamp should turn ON and OFF when changing between the commanded states.
| ⇒ | If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the PCM/TCM. |
| ⇒ | If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the PCM/TCM. |
- If all circuits test normal, replace the differential clutch pump actuator check valve.
Repair Instructions
