DTC P129B or P129C

Diagnostic Instructions 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. DTC Descriptor DTC P129B Fuel Pump Driver Control Module System Voltage Low Voltage DTC P129C Fuel Pump Driver Control Module System Voltage High Voltage For symptom byte information refer to Symptom Byte List. Circuit/System Description The K111 Fuel Pump Power Control Module monitors the system voltage on circuit 1940 to ensure that it stays within the proper range. An open or high resistance on the ground circuit 1950 may affect the K111 Fuel Pump Power Control Modules ability to monitor and report the correct system voltage. Conditions for Running the DTC Ignition On Conditions for Setting the DTC B+ circuit 1940 is less than 9 V for more than 5 s or ground circuit 1950 has an open or high resistance. B+ circuit 1940 is greater than 15 V for more than 5 s or ground circuit 1950 has an open or high resistance. Actions Taken When the DTC Sets A message and/or warning indicator may be displayed to the driver The K111 Fuel Pump Power Control Module may be disabled Conditions for Clearing the DTC The conditions for setting the DTC are no longer present A history DTC will clear after 100 consecutive ignition cycles without a fault Diagnostic Aids If the fault is not current, the high system voltage could be a result of overcharging with a battery charger or after jump starting the vehicle. Reference Information Schematic Reference Starting and Charging Schematics Control Module References Connector End View Reference Master Electrical Component List Electrical Information Reference Circuit Testing Connector Repairs Testing for Intermittent Conditions and Poor Connections Wiring Repairs DTC Type Reference Powertrain Diagnostic Trouble Code (DTC) Type Definitions Scan Tool Reference Control Module References Circuit/System Verification

1. Ignition ON.

Note

A low or high voltage DTC may set in multiple control modules due to a concern with the battery or charging system.

2. Verify there are no system voltage DTCs set as current or history in any control module. ⇒ If any system voltage DTCs are set Diagnose these DTCs first. Refer to Diagnostic Trouble Code (DTC) List - Vehicle. ⇓ If no system voltage DTCs are set
3. Ignition Off and all vehicle systems OFF.

Note

The battery voltage should stabilize after a few minutes of turning the ignition/vehicle Off.

4. Verify the battery voltage is between 12.4 V to 12.8 V at the C1 Battery. ⇒ If not between the specified range Refer to Battery Inspection/Test ⇓ If between the specified range
5. Engine Running with all accessories off, allow the system voltage to stabilize.
6. Test for 13 V to 15 V at the C1 Battery. ⇒ If not the specified value Refer to Charging System Test ⇓ If the specified range
7. Verify DTC P129B or P129C is set as current. ⇒ If DTC DTC P129B or P129C is set as current Refer to Circuit/System Testing. ⇓ If DTC P129B or P129C is not set as current
8. A fault is not currently present and may be an intermittent condition. Circuit/System Testing
9. Ignition Off, disconnect the connector at the K111 Fuel Pump Power Control Module.
10. Verify a test lamp illuminates between ground circuit terminal 22 and B+ ⇒ If the test lamp does not illuminate Repair the open/high resistance on circuit 1950 or the ground connection. ⇓ If the test lamp illuminates
11. Ignition ON.
12. Verify a test lamp Illuminates between B+ circuit terminal 7 and ground. ⇒ If the test lamp does not illuminate and the circuit fuse is good 4.1. Test circuit 1940 for an open/high resistance. ⇒ if an open/high resistance is found, repair the fault on the circuit. ⇓ If an open or high resistance is not found 4.2. 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 4.1. Test circuit 1940 for a short to ground ⇒ If a short to ground is found, repair the fault on the circuit. ⇓ If a short to ground is not found 4.2. Replace the K111 Fuel Pump Power Control Module ⇓ If the test lamp illuminates
13. Verify the voltage at B+ terminal 7 is within 1 V of the C1 Battery voltage. ⇒ If not within the specified value Repair the high resistance on circuit 1940. ⇓ If within the specified value
14. Replace the K111 Fuel Pump Power Control Module. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair. Control Module References for control module replacement, programming, and setup