DTC P1255 or P064A. GMC Truck Sierra

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 2007 🢒 Sierra - 2WD 🢒 Driver Information and Entertainment 🢒 Cellular, Entertainment, and Navigation 🢒 DTC P1255 or P064A

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 Descriptors

DTC P064A 00: Fuel Pump Flow Control Module Performance

DTC P1255 00: Fuel Pump Flow Control Module Driver Overtemperature

The engine control module (ECM) supplies a high voltage signal to the fuel pump flow control module (FPCM) when the ECM detects that the ignition is on. The high voltage signal from the ECM to the FPCM remains active for two seconds, unless the engine is in crank or run. While this signal is being received, the FPCM closes the ground switch of the fuel pump and also supplies a varying voltage to the fuel tank pump module in order to maintain the desired fuel rail pressure.

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

•	The FPCM detects an overtemperature fault.

•	The above condition is present for greater than 12.5 milliseconds.

Action Taken When the DTC Sets

•	The malfunction indicator lamp (MIL) will illuminate.

•	The FPCM records the operating conditions at the time the diagnostic fails. The FPCM stores this information in the Failure Records.

Conditions for Clearing the DTC

•	A last test failed, or the current DTC, clears when the diagnostic runs and does not fail.

•	A history DTC clears after 40 consecutive warm-up cycles, if failures are not reported by this or any other emission related diagnostic.

Diagnostic Aids

Using the Failure Records data may help locate an intermittent condition. If you cannot duplicate the DTC, the information in the Failure Records can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can help determine how many ignition cycles that the diagnostic test reported a pass and/or a fail.

Reference Information

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

Scan Tool Reference

•	Scan Tool Data List

•	Scan Tool Data Definitions

Circuit/System Testing

Important: Verify that P0231, P0232 or P023F are not set as current or history before performing this diagnostic. If any of those codes are set as current or history, go to DTC P0231, P0232, or P023F .

Check that the entire undercarriage of the vehicle is clean, especially around the spare tire area where the FPCM is located. Clear all codes from the FPCM and test drive the vehicle. Verify that DTC P1255 or P064A do not set as current.

⇒	If DTC P1255 or P064A reset as current, replace the FPCM.

If the DTCs do not set in the FPCM again, the system is okay. Do not replace the FPCM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for FPCM replacement, setup, and programming