GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2009 🢒 Corvette 🢒 Driver Information and Entertainment 🢒 Cellular, Entertainment, and Navigation 🢒 DTC P129D

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 P129D: Fuel Pump Driver Control Module Ignition 1 Switch Circuit Low Voltage

Diagnostic Fault Information

Circuit

Short to Ground

Open or High Resistance

Short to Voltage

Signal Performance

IGN Voltage

P129D

P129D

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Circuit/System Description

The fuel pump flow control module (FPCM) monitors the IGN voltage circuit in order to determine if the voltage is within the normal operating range.

Conditions for Running the DTC
    • The key is in Run or Crank.
    • The engine is running.

Conditions for Setting the DTC
    • The FPCM detects that the IGN voltage is less than 6.0 V.
    • The above condition is present for 7 seconds.

Action Taken When the DTC Sets

DTC P129D is a Type A DTC.

Conditions for Clearing the DTC

DTC P129D is a Type A DTC.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Fuel System Description

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

Fuel Pump Flow Control Module Scan Tool Information for scan tool information

Circuit/System Testing

Important: 

  1. Verify that DTC P0562 is not set.
    2. ⇒ If DTC P0562 is set, refer to DTC P0562.
  2. Ignition OFF, disconnect the harness connectors at the FPCM, and X2 at the FPCM relay.
  3. Connect a test lamp between the appropriate IGN voltage circuit terminals listed below and ground.
    4. • FPCM terminal 15
    • FPCM relay terminal 5
  4. Ignition ON, verify the test lamp turns on.
    5. ⇒If the test lamp is OFF, test the IGN voltage circuit a short to ground or an open/high resistance.
  5. Ignition OFF, connect the harness connector at the FPCM.
  6. Connect a test lamp between the X2 FPCM relay harness connector terminal 5 and ground.
  7. Ignition ON, verify the test lamp is ON.
    8. ⇒If the test lamp is OFF, test the IGN voltage circuit an open/high resistance. If the circuit tests normal, replace the FPCM.
  8. If all circuits test normal, replace the FPCM relay.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Fuel Pump Flow Control Module Replacement
    •  Fuel Pump Flow Control Module Relay Replacement
    •  Control Module References for FPCM replacement, setup, and programming