2010 Cadillac CTS Sedan AWD V6-3.6L Page 1534
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
P0629
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
received. While this enable voltage is being received, the fuel pump flow control module supplies a varying voltage to the in-tank fuel pump
module in order to maintain the desired fuel line pressure.
Conditions for Running the DTC
* The engine speed is greater than 80 RPM.
* The ignition 1 signal parameter is 10-18 V.
* The ECM has commanded the fuel pump enable circuit ON and OFF at least once during the ignition cycle.
* The DTCs run continuously when the conditions above are met.
Conditions for Setting the DTC
P0627
The ECM detects the fuel pump enable circuit voltage is less than 2.74 V when the enable circuit is commanded OFF. The condition exists for
