• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
• | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
• | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
---|---|---|---|---|
Trans. Aux. Oil Pump Control -- Circuit 983 | P2797 | P2797 | P2797 | -- |
Trans. Aux. Oil Pump Diagnostic -- Circuit 982 | P0C2B | P0C2B | P0C2B | -- |
Condition | Short to Ground | Open | Short to Voltage |
---|---|---|---|
Operating Conditions: Ignition ON Parameter Normal Range: No Fault | |||
Trans. Aux. Oil Pump Control -- Circuit 983 | PWM Input Fault | PWM Input Fault | PWM Input Fault |
Condition | Short to Ground | Open | Short to Voltage |
---|---|---|---|
Operating Conditions: Ignition ON Parameter Normal Range: No Fault | |||
Trans. Aux. Oil Pump Diagnostic -- Circuit 982 | No PWM Response | No PWM Response | No PWM Response |
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 an 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 control circuit delivers the HPCM commanded pump speed to the ATFP control module. The transmission auxiliary oil pump 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 12V direct current (dc) into 12V, 3 phase ac current to operate the pump motor.
The ATFP control module monitors the status of the ATFP motor/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 over the transmission auxiliary oil pump diagnostic circuit. The diagnostic status within the ATFP control module is reset at every ignition-off cycle.
• | Ignition voltage is 8-18 volts. |
• | The auxiliary transmission fluid pump is commanded ON. |
The HPCM observes the difference between actual and commanded ATFP pump speed is greater than 500 RPM for 4 out of 4.125 seconds.
• | DTC P2797 is a Type B DTC. |
• | The drive motor generator power inverter control module (PIM) disables the Autostop hybrid mode. |
DTC P2797 is a Type B DTC.
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Control Module References for scan tool information
J 38522 Variable Signal Generator
⇒ | If the actual speed is within 10 percent of commanded speed an electrical fault condition is not currently present, if an aux. trans. fluid pump pressure fault is suspected, test the aux. trans. pump line pressure output. Refer to Line Pressure Check. |
⇒ | If the difference between actual and commanded speed is greater than 10 percent, the pump is noisy, or the pump stalls, proceed to Circuit/System Testing. |
⇒ | Refer to the applicable diagnostic procedure below for the fault status indicated by the scan tool display. |
⇒ | If No Fault status is displayed, review the Freeze Frame/Failure Records and perform the diagnosis indicated by the Fault Status parameter display. |
⇒ | If less than the specified range, test the control circuit for an open or short to ground. If the circuit tests normal, replace the ATFP Control Module. |
Important: Only connect the J 38522 to the ATFP control circuit when adjusted to 50 percent duty cycle. Duty cycles of less than 50 percent may damage the ATFP pump assembly.
⇒ | If pump operation is audible, replace the PIM. |
⇒ | If pump operation is not audible, continue with Circuit/System Testing. |
⇒ | If greater than the specified range, test the control circuit for a short to voltage. |
⇒ | If equal to the specified range, replace the ATFP control module. |
This display indicates the ATFP 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. |
⇒ | 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 ATFP control module and repeat Circuit/System Verification. |
Pump Connector X2 Terminal | Pump Connector X2 Terminal | Specified Range |
---|---|---|
A | E | < 0.5 OHMS |
A | C | < 0.5 OHMS |
C | E | < 0.5 OHMS |
A | F | OL |
C | F | OL |
E | F | OL |
A | Chassis Ground | OL |
C | Chassis Ground | OL |
E | Chassis Ground | OL |
This display indicates an internal ATFP control module fault exists, no external circuits are involved. Replace the ATFP control module.
This display indicates an internal ATFP control module fault exists, no external circuits are involved. Replace the ATFP control module.
⇒ | If actual battery voltage measures less than the value range, increase actual battery voltage and repeat Circuit/System Testing. |
⇒ | If actual battery voltage measures more than the value range, test the ATFP control module power and ground circuits for a high resistance condition. If the circuits test normal, replace the ATFP control module. |
⇒ | If actual temperature is the same or more than the value range, no action is necessary. |
⇒ | If actual temperature is less than the value range, replace the ATFP control module. |
⇒ | If actual temperature is the same or more than the value range, no action is necessary. |
⇒ | If actual temperature is less than the value range, replace the ATFP control module. |
• | Low or cavitating automatic transmission fluid |
• | Poor terminal connection or wiring degradation |
• | External indication of ATFP pump motor damage |
⇒ | If none of the conditions are observed, replace the ATFP motor/pump assembly and the ATFP control module. |
This display indicates an internal ATFP control module fault exists, no external circuits are involved. Replace the ATFP control module.
• | Automatic transmission fluid pressure trapped internally |
• | Poor terminal connection or wiring degradation |
• | External indication of ATFP pump motor damage |
⇒ | If none of the conditions are observed, replace the ATFP motor/pump assembly and the ATFP control module. |
This display indicates the HPCM does not detect the ATFP Control Feedback circuit signal. Refer to DTC P0C2B.
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for PIM or ATFP control module replacement, setup, and programming |