P2797
DTC P2797
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptor
DTC P2797
-
Auxiliary Transmission Fluid Pump Performance
Diagnostic Fault Information
Circuit/System Description
The generator control module also called the starter generator control module is comprised of the following three control modules; the hybrid powertrain control module, 14 volt power module and the drive motor control module. These three control modules are non serviceable and are part of the generator control module.
The transmission fluid pump - auxiliary is used to maintain transmission fluid line pressure to the transmission during Autostop mode. The transmission fluid pump - auxiliary is externally mounted to the transmission case assembly. The hybrid powertrain control module controls the auxiliary pump by providing the ground path to the transmission pump relay - auxiliary coil control circuit.
Conditions for Running the DTC
* The Ignition is ON.
* The system voltage is between 9.0 and 32.0 V.
Condition 1
The vehicle is in autostop mode.
Condition 2
* All conditions allowing an autostop have been met.
* A/C compressor ON.
Conditions for Setting the DTC
Condition 1
The calculated transmission slip speed is greater than 150 RPM during a vehicle launch from autostart mode, 7 consecutive times in the same key cycle.
Condition 2
The 14 volt power module output current does not increase by 100 watts or more when the auxiliary transmission fluid pump is commanded ON by the hybrid powertrain control module.
OR
The 14 volt power module output current does not decrease by greater than 250 watts when the auxiliary transmission fluid pump is commanded OFF by the hybrid powertrain control module.
Action Taken When the DTC Sets
* The hybrid powertrain control module disables the Autostop mode.
* DTC P2797 is a Type B DTC.
Conditions for Clearing the DTC
DTC P2797 is a Type B DTC.
Diagnostic Aids
Driving a vehicle with an auxiliary transmission fluid pump failure that causes low or no pressure will cause a harsh transmission engagement on vehicle launch from an autostop.
Reference Information
Schematic Reference
Hybrid Controls Schematics Hybrid Controls Schematics
Description and Operation
* Generator Control Module Description and Operation Generator Control Module Description and Operation
* Hybrid Modes of Operation Description Hybrid Modes of Operation Description
* Starter Generator Description and Operation Starter Generator Description and Operation
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Circuit/System Verification
1. Verify that no other hybrid powertrain or transmission control module DTC is set.
• If any hybrid powertrain or transmission control module DTC is set
Refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle.
2. Perform the Transmission Fluid Level and Condition Check Transmission Fluid Level and Condition Check to verify correct fluid level and condition.
3. Ignition ON.
4. Verify the auxiliary transmission fluid pump turns ON and OFF when commanding the auxiliary transmission fluid pump relay ON and OFF with a scan tool.
• If the pump does not operate
Refer to Circuit/System Testing.
• If the pump operates
All OK. Refer to transmission Line Pressure Check Line Pressure Check.
Circuit/System Testing
1. Ignition OFF, disconnect the KR86 transmission fluid pump relay - auxiliary, Ignition ON.
2. Verify a test lamp illuminates between the B+ circuit terminal 30 and ground.
• If the test lamp does not illuminate and the circuit fuse is good
1. Ignition OFF.
2. Test for less than 2 ohms in the B+ circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse.
• If the test lamp does not illuminate and the circuit fuse is open
1. Ignition OFF.
2. Test for infinite resistance between the B+ circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Disconnect the X1 harness connector at the G5 Transmission Fluid Pump - Auxiliary, test for infinite resistance between the switched control circuit terminal 1 and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the G5 Transmission Fluid Pump - Auxiliary.
• If the test lamp illuminates
3. Ignition OFF and all vehicle systems OFF, disconnect the X1 harness connector at the G5 Transmission Fluid Pump - Auxiliary. It may take up to 2 minutes for all vehicle systems to power down.
4. Test for less than 10 ohms between the G5 Transmission Fluid Pump - Auxiliary ground circuit X1 terminal 2 and ground.
• If 10 ohms or greater
1. Ignition OFF.
2. Test for less than 2 ohms in the ground circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, repair the open/high resistance in the ground connection.
• If less than 10 ohms
5. Connect the harness connector at the G5 Transmission Fluid Pump - Auxiliary.
6. Connect a 30 A fused jumper wire between the B+ circuit terminal 30 and the switch control circuit terminal 87. Ignition ON.
7. Verify the G5 Transmission Fluid Pump - Auxiliary is ON.
• If the Pump is not ON
1. Ignition OFF.
2. Test for less than 2 ohms in the switch control circuit terminal 87 end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, test or replace the G5 Transmission Fluid Pump - Auxiliary.
• If the Pump is ON
8. Test or replace the KR86 Transmission Fluid Pump Relay - Auxiliary.
• If the DTC resets
9. Refer to transmission Line Pressure Check Line Pressure Check.
Component Testing
1. Ignition OFF, disconnect the KR86 Transmission Fluid Pump Relay - Auxiliary.
2. Test for 85-130 ohms between terminals 85 and 86.
• If less than 85 ohms or greater than 130 ohms
Replace the relay.
• If between 85-130 ohms
3. Test for infinite resistance between the terminals listed below:
* 30 and 86
* 30 and 87
* 30 and 85
* 85 and 87
• If less than infinite resistance
Replace the relay.
• If infinite resistance
4. Install a 3 A fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground.
5. Test for less than 2 ohms between terminals 30 and 87.
• If 2 ohms or greater
Replace the relay.
• If less than 2 ohms
6. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Auxiliary Fluid Pump Removal (Hybrid) 3. Auxiliary Fluid Pump Removal (Hybrid)
* Relay Replacement (Within an Electrical Center) Relay Replacement (Within an Electrical Center)Relay Replacement (Attached to Wire Harness) Relay Replacement (Attached to Wire Harness) , Within an Electrical Center, for Transmission Fluid Pump Relay - Auxiliary replacement.