Circuit/System Testing

NOTE:

It is important, that while performing the testing steps below, that the vehicle is not keyed off until after the fault status/freeze frame failure has been identified. Certain failures can cause customer concerns but may not immediately set a DTC. Depending on the failure and severity the fault status may change briefly or latch as a result of the event but will clear once the vehicle has been keyed off.

1. Ignition ON, engine OFF, observe the Aux. Trans. Fluid Pump Fault Status 1 and Aux. Trans. Fluid Fault Status 2 displays with the scan tool.
   • If there is a fault currently active, refer to the applicable diagnostic procedure below for the fault status indicated by the scan tool display.
2. Using the scan tool, command the aux. trans. fluid pump speed to 50 percent and maintain pump operation for at least 60 seconds while observing the fault status displays. The actual pump speed should be maintained within 10 percent of commanded. The pump should not make excessive noise or stall.
   • If there is a fault currently active as a result of the manual speed command test, refer to the applicable diagnostic procedure below for the fault status indicated by the scan tool display.
   • If the actual speed is within 10 percent of commanded speed an aux. trans. fluid pump pressure fault could be present, test the aux. trans. pump line pressure output. Refer to Line Pressure Check .
   • If there is not a fault currently active as a result of the manual speed command test, and DTC P2797 is either active or in history, review the Freeze Frame/Failure Records for the DTC and perform the diagnosis indicated by the Fault Status parameter display within the Freeze Frame/Failure Records.
3. Perform an aux pump stress drive cycle, following an 8 hour ambient soak:
   • Apply parking brake
   • While in Autostop, recreate the condition by brake torquing to achieve motor 2 torque between 110-160 N.m (81-118 lb ft). Maintain for at least 30 seconds and release pedal for approximately 10 seconds, repeat test at least 10 times while observing the following parameters:
     • Pump Speed
     • Control Module Voltage, should be at least 12V
     • Aux. Trans. Fluid Pump Fault Status 1 and 2
     • If the difference between actual and commanded speed is greater than 10 percent, the pump is noisy, or the pump stalls, refer to Circuit/System Testing.
4. If the customer's concern can not be duplicated and No Fault status is displayed, the failure is likely related to a faulty auxiliary transmission fluid pump control module and therefore the module should be replaced.

PWM Input Fault

1. Ignition OFF, disconnect power inverter module connector X1.
2. Ignition ON, test for 11-13V on the Trans. Aux. Oil Pump Control circuit from power inverter module connector X1 terminal 5 and chassis ground.
   • If less than the specified range, test the control circuit for an open or short to ground. If the circuit tests normal, replace the auxiliary transmission fluid pump Control Module.
NOTE:

Only connect the J 38522  variable signal generator to the auxiliary transmission fluid pump control circuit when adjusted to 50 percent duty cycle. Duty cycles of less than 50 percent may damage the auxiliary transmission fluid pump assembly.

3. Pre-Adjust the J 38522  variable signal generator to 50 percent duty cycle @ 250 Hz.
4. Connect the J 38522  variable signal generator to the Trans. Aux. Oil Pump Control circuit, from the power inverter module connector X1 terminal 5 and ground and listen for auxiliary transmission fluid pump motor operation.
   • If pump operation is audible, replace the power inverter module.
   • If pump operation is not audible, continue with Circuit/System Testing.
5. Ignition OFF, disconnect the auxiliary transmission fluid pump control module connector X1.
6. Ignition ON, test for 0V on the Trans. Aux. Oil Pump control circuit from power inverter module connector X1 terminal 5 and chassis ground.
   • If greater than the specified range, test the control circuit for a short to voltage.
   • If equal to the specified range, replace the auxiliary transmission fluid pump control module.

Motor/Open Short 

This display indicates the auxiliary transmission fluid pump control module has detected one of the following pump motor current conditions:

• At least one phase current is more than 70 A.
• Commanded current is more than 5 A and actual current in any phase is less than 2 A.

1. Ignition OFF, disconnect the auxiliary transmission fluid pump control module connector X2.
2. Inspect both connectors for TPA and terminal tension / retention, backed out terminals, discoloration, etc.
3. Using the Auxiliary Fluid Pump Specification table listed below, test the resistance between the X2 circuits of the pump connector as indicated.
   • If any of the circuits are not within the specified range, replace the pump assembly and repeat the Circuit/System Verification.
   • If all circuits test normal, replace the auxiliary transmission fluid pump control module and repeat Circuit/System Verification.

Motor CKT Fault 

This display indicates an internal auxiliary transmission fluid pump control module fault exists, no external circuits are involved. Test pump circuits for a short to ground before replacing controller and test controller circuits for a short to ground.

1. Test the following auxiliary transmission fluid pump circuits for a short to ground:
   • Auxiliary transmission fluid pump phase A X2 terminal 1
   • Auxiliary transmission fluid pump phase B X2 terminal 2
   • Auxiliary transmission fluid pump phase C X2 terminal 3
   • If the auxiliary transmission fluid pump is shorted to ground, replace auxiliary transmission fluid pump.
2. Test the following auxiliary transmission fluid control module circuits for a short to ground:
   • Auxiliary transmission fluid pump control module phase A X2 terminal 1
   • Auxiliary transmission fluid pump control module phase B X2 terminal 2
   • Auxiliary transmission fluid pump control module phase C X2 terminal 3
   • If the transmission fluid pump control module is shorted to ground, replace the transmission fluid pump control module.

If the circuits test normal, replace the auxiliary transmission fluid pump and the auxiliary transmission fluid pump control module.

Temp Sen Fault 

This display indicates an internal auxiliary transmission fluid pump control module fault exists, no external circuits are involved. Replace the auxiliary transmission fluid pump control module.

Low Voltage 

This display indicates the auxiliary transmission fluid pump control module has monitored battery voltage less than desired operating voltage.

1. Measure actual battery voltage with a DMM at both the 12 volt battery and the DC supply harness to the auxiliary transmission fluid pump control module.
   • If actual battery voltage measures less than the value range, proceed to step 2.
   • If actual battery voltage measures more than the value range, test the auxiliary transmission fluid pump control module power and ground circuits for a high resistance condition. If the circuits test normal, replace the auxiliary transmission fluid pump control module.
2. Verify 12V battery and accessory DC Power conversion control module condition, Accessory DC Power Control Module Scan Tool Information .

Auxiliary Transmission Fluid Pump Control Module Over temp 

This display indicates an internal auxiliary transmission fluid pump control module fault exists, no external circuits are involved. Replace the auxiliary transmission fluid pump control module.

Auxiliary Transmission Fluid Pump Control Module Hot 

This display indicates an internal auxiliary transmission fluid pump control module fault exists, no external circuits are involved. Replace the auxiliary transmission fluid pump control module.

Current High/Lo

1. This display indicates the auxiliary transmission fluid pump control module has monitored motor current that is outside the normal range for a given motor speed.
2. Inspect for the following conditions:
   • Low or cavitating automatic transmission fluid - Verify line pressure
   • Poor terminal connection or wiring degradation, controller and pump
   • External indication of auxiliary transmission fluid pump pump motor damage
   • If none of the conditions are observed, replace the auxiliary transmission fluid pump.

Current Fault 

This display indicates an internal auxiliary transmission fluid pump control module fault exists, no external circuits are involved. Replace the auxiliary transmission fluid pump control module.

No Start 

This display indicates the auxiliary transmission fluid pump control module has monitored excess motor current during motor start-up.

Inspect for the following conditions:

• Automatic transmission fluid pressure trapped internally, verify line pressure check is normal
• Poor terminal connection or wiring degradation
• External indication of auxiliary transmission fluid pump pump motor damage
  • If none of the conditions are observed, replace the auxiliary transmission fluid pump control module.

No PWM Response 

This display indicates the hybrid powertrain control module does not detect the auxiliary transmission fluid pump Control Feedback circuit signal. Refer to DTC P0C2B .