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For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2007 🢒 Sierra Denali 🢒 Driver Information and Entertainment 🢒 Cellular, Entertainment, and Navigation 🢒 DTC P2534

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 P2534 00: Ignition 1 Switch Circuit Low Voltage

Circuit/System Description

The fuel pump flow control module (FPCM) monitors the ignition 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 II/III voltage is less than 6.0  volts.
    • The above condition is present for 7 seconds.

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 100 consecutive warm-up cycles, if failures are not reported by this or any other emission related diagnostic.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Engine Controls 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

Scan Tool Reference

    •  Scan Tool Data List
    •  Scan Tool Data Definitions

Circuit/System Testing

Important: Verify that P0562 is not set as current or history before performing this diagnostic. If P0562 is set as current or history, go to DTC P0562 .

  1. Ignition OFF, disconnect the harness connector of the FPCM.
  2. Ignition ON, test for 11 volts or greater between the IGN II/III voltage circuit terminal 15 and ground.
    3. ⇒If less than the specified voltage, test the IGN II/III voltage circuit for a short to ground or an open/high resistance. If the circuit test normal and the ECM - IGN fuse 58 is open, test the voltage circuit for a short to ground. If the circuit tests normal, test or replace the RUN/CRANK relay.
  3. If all circuits test normal, replace the FPCM.

Component Testing

Relay Test

  1. Ignition OFF, disconnect the RUN/CRANK relay.
  2. Test for 60-180 ohms between terminals 85 and 86.
    3. ⇒ If the resistance is not within the specified range, replace the relay.
  3. Test for infinite resistance between the following terminals:
    4. • 30 and 86
    • 30 and 87
    • 30 and 85
    • 85 and 87
    ⇒If less than infinite resistance, replace the RUN/CRANK relay.
  4. Install a 20-amp fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Test for less than 2.0 ohms between terminals 30 and 87.
    5. ⇒If greater than 2.0 ohms, replace the RUN/CRANK relay.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for FPCM replacement, setup, and programming