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Home >> Chevrolet >> 2006 >> Silverado 1500 HD, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 937 (Engine Controls And Fuel - 4.8L, 5.3L, 6.0L And 6.2L - DTC P0231 To DTC P1255) >> DTC P025A >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2007 GMC Sierra, 2007 GMC Cab & Chassis Sierra, 2007 Chevrolet Silverado, and 2007 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
IMPORTANT: Repair all U-codes before performing this diagnostic.
  1. Ignition OFF, disconnect the harness connectors at the ECM X1 and the FPCM.
  2. Ignition ON, test for 0 volts between the FPCM harness connector terminal 13 and ground.
    • If greater than the specified voltage, test the fuel control enable signal circuit for a short to voltage.
  3. Ignition OFF, test for infinite resistance between the FPCM harness connector terminal 13 and ground.
    • If less than the specified range, test the fuel control enable signal circuit for a short to ground.
  4. Ignition OFF, test for 1.0 ohm or less between the ECM harness connector X1 terminal 50 and FPCM harness connector terminal 13.
    • If greater than the specified range, test the fuel control enable signal circuit for an open/high resistance.
  5. Reconnect the harness connectors at the ECM and the FPCM. Within 2 seconds of ignition ON, with a scan tool, verify that the Fuel Pump Command parameter displays ON.
    • If the parameter does not display ON within the 2 seconds of ignition ON, replace the ECM.
  6. If all circuits test normal, replace the FPCM.
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