2010 Cadillac CTS Sedan AWD V6-3.6L Page 1532
Scan Tool Reference
Control Module References (See: Testing and Inspection/Programming and Relearning) for scan tool information
Circuit/System Verification
1. Attempt to start the engine. Observe the DTC information with a scan tool. DTC P0627, P0628, or P0629 should not set.
2. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the
conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing
1. Ignition OFF, disconnect the K27 fuel pump control module harness connector.
2. Connect a test lamp between the enable circuit terminal 13 of the fuel pump control module and ground.
3. Ignition ON, command the fuel pump ON and OFF with a scan tool. The test lamp should turn ON and OFF as commanded.
瀚慖f the test lamp remains OFF all the time, test for a short to ground or an open/high resistance on the enable circuit. If the
circuit/connections test normal, replace the K20 ECM.
瀚慖f the test lamp remains ON all the time, test for a short to voltage on the enable circuit. If the circuit/connections test normal, replace the
K20 ECM.
4. Ignition ON, test for 2-3 V on the enable circuit terminal 13 of the fuel pump control module.
瀚慖f not within the specified range, replace the K20 ECM.
5. If all circuits/connections test normal, replace the K27 fuel pump control module.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* Fuel Pump Flow Control Module Replacement (See: Powertrain Management/Fuel Delivery and Air Induction/Fuel Pump/Service and
Repair)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for ECM or fuel pump control module replacement,
setup, and programming
P0628
DTC P0627-P0629 (w/LLT)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptors
DTC P0627
- Fuel Pump Enable Circuit
DTC P0628
- Fuel Pump Enable Circuit Low Voltage
DTC P0629
- Fuel Pump Enable Circuit High Voltage
Diagnostic Fault Information
Circuit/System Description
The engine control module (ECM) provides ignition voltage to the fuel pump flow control module whenever the engine is cranking or running. The
control module enables the fuel pump flow control module as long as the engine is cranking or running, and ignition system reference pulses are
