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Home >> GMC >> 2006 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1647 (Engine Control System & Fuel System - 4.8L, 5.3L, 6.0L, 6.2L - DTC P1255 To DTC P3449) >> DTC P2632 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2010 GMC Sierra, 2010 GMC Cab & Chassis Sierra, 2010 Chevrolet Silverado, and 2010 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the secondary fuel pump relay.
  2. Ignition ON, verify that a test lamp illuminates between the ground circuit terminal and B+.
    • If the test lamp does not illuminate, test the ground circuit for a short to voltage or an open/high resistance.
  3. Verify that a test lamp does not illuminate between the ground circuit terminal and the control circuit terminal.
    • If the test lamp illuminates, test the control circuit for a short to voltage. If the circuit tests normal, replace the ECM.
  4. Remove the test lamp.
  5. Command the fuel pump relay ON with a scan tool. Verify the scan tool fuel pump relay Ckt. Short Grnd Test Status parameter is OK.
    • If not the specified value, test the secondary fuel pump relay control circuit for a short to ground. If the circuit tests normal, replace the ECM.
  6. Install a 3 A fused jumper wire between the secondary fuel pump relay control circuit terminal and the ground circuit terminal. Command the fuel pump ON with a scan tool. Verify the scan tool fuel pump relay Ckt. Short Grnd Test Status parameter is Fault.
    • If not the specified value, test the secondary fuel pump relay control circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
  7. If all circuits test normal, test or replace the secondary fuel pump relay.
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