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Home >> GMC >> 2006 >> Sierra 1500 HD, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1147 (Engine Controls And Fuel - 3.6L - DTC P0137 To DTC P0497) >> DTC P0452 or P0453 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2008 Cadillac CTS. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, remove the fuse that supplies B+ to terminal X2-56 of the ECM.
  2. Disconnect the C-420 harness connector at the rear of the fuel tank.
  3. Test for less than 5.0 ohms of resistance between the low reference circuit terminal E and ground, at the ECM side of the connector.
    • If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit/connections test normal, replace the ECM.
  4. Install the fuse that supplies B+ to terminal X2-56 of the ECM.
  5. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal C and ground, at the ECM side of connector C-420.
    • If less than the specified range, test the 5-volt reference circuit for a short to ground or open/high resistance. If the circuit/connections test normal, replace the ECM.
    • If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit/connections test normal, replace the ECM.
  6. Verify that the FTP Sensor parameter is less than 4.8 volts
    • If greater than the specified value, test the signal circuit for a short to voltage. If the circuit/connections test normal, replace the ECM.
  7. At the ECM side of C-420, install a 3A fused jumper wire between the signal circuit terminal B and the 5-volt reference circuit terminal C. Verify that the FTP Sensor parameter is greater than 4.8 volts.
    • If less than the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit/connections test normal, replace the ECM.
  8. Remove the fuel tank. Refer to Fuel Tank Replacement .
  9. Disconnect the FTP sensor connector.
  10. Inspect the FTP sensor circuits in the fuel tank harness, between the FTP sensor connector and C-420 for the following conditions, and repair as necessary:
    • Damaged wiring or terminals
    • Open circuits
    • Short to ground
    • Wire to wire short
  11. If all circuits/connections test normal, test or replace the FTP sensor.
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