The auxiliary transmission fluid pump (ATFP) system supplies the transmission with hydraulic pressure when the vehicle is operating in the internal combustion engine (ICE) Autostop hybrid mode. The ATFP system consists of a ATFP control module that operates an electric, 12V 3 phase alternating current (ac), motor-driven pump. Two pulse width modulated (PWM) status circuits connect the ATFP control module to the hybrid powertrain control module (HPCM). The transmission auxiliary oil pump (TAOP) control circuit delivers the HPCM commanded pump speed to the ATFP control module. The transmission auxiliary oil pump (TAOP) diagnostic circuit supplies the HPCM with the actual pump speed and also with the operating status of the ATFP control module. The HPCM monitors these circuits for fault conditions.

The ATFP control module inverts 12 v direct current (dc) into 12 v, 3 phase ac current to operate the pump motor.

The ATFP control module monitors the status of the ATFP pump as well as its own internal circuitry. The ATFP control module does not store its own diagnostic status. Current ignition cycle diagnostic status is reported to the HPCM on the TAOP diagnostic circuit. The diagnostic status within the ATFP control module is reset at every ignition-off cycle.

The control module has not detected the ATFP diagnostic signal for 1.5 seconds.

DTC P0C2B is a Type B DTC.

The engine harness connector for the ATFP control module and the mating connector for the transmission auxiliary pump motor can be improperly connected to each other. The following conditions may be observed if the improper connectors are mated together:

Schematic Reference

Hybrid Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Special Tools

J 38522 Variable Signal Generator

1. Clear the DTC information.
2. Turn the ignition OFF for 1 minute.
3. Turn the ignition ON.
4. Retest for DTC P0C2B.

Note: Ensure the engine harness connector is properly mated to the ATFP control module and the transmission auxiliary pump motor is properly mated to the ATFP control module before continuing with circuit/system testing. Refer to Diagnostic Aids.

1. Ignition OFF, disconnect ATFP X1 connector.
2. Ignition ON, test for battery voltage on the ATFP battery circuit, from ATFP X1 connector terminal A and chassis ground.

⇒	If less than battery voltage, test the ATFP battery circuit for an open/high resistance. If the circuit tests normal, continue with diagnosis.

Note: If an open ground condition is observed, inspect the 3 phase motor shield circuit and terminal for damage.

3. Test for battery voltage on the ATFP battery circuit from ATFP X1 connector terminal A and the ATFP ground circuit connector X1 terminal C.

⇒	If less than the specified range, test the ATFP ground circuit for an open/high resistance. If the circuit tests normal, continue with diagnosis.

4. Test for battery voltage on the ATFP ignition circuit from ATFP X1 connector terminal E and the ATFP ground circuit connector X1 terminal C.

⇒	If less than the specified range, test the ATFP ignition circuit for an open/high resistance. If the circuit tests normal, continue with diagnosis.

5. Test for 4.8-5.2 volts on the Trans. Aux. Oil Pump Diagnostic circuit, from the ATFP X1 connector terminal D and ground.

⇒	If less than the specified range, test the Trans. Aux. Oil Pump Diagnostic circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the PIM.

⇒	If more than the specified range, test the Trans. Aux. Oil Pump Diagnostic circuit for a short to voltage. If the circuit tests normal, replace the PIM.

6. Connect the J 38522 variable signal generator red terminal to the Trans. Aux. Oil Pump Diagnostic circuit, ATFP X1 connector terminal D, vehicle harness side. Connect the J 38522 variable signal generator black terminal to chassis ground.
7. Adjust the signal generator to 50 percent duty cycle @ 250 Hz and observe the Trans. Aux. Pump Actual speed parameter with the scan tool. The scan tool should display 100 percent.

⇒	If less than 100 percent, test the Trans. Aux. Oil Pump Diagnostic circuit for a short to 5V. If the circuit tests normal, replace the PIM.

⇒	If 100 percent is displayed, replace the ATFP control module.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for PIM or ATFP control module replacement, setup, and programming