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Home >> Buick >> 2007 >> Allure CX >> Repair and Diagnosis >> External Pages >> Different car >> Section 68 (Engine Control System & Fuel System - 3.6L - DTC P0335 To DTC P2097) >> DTC P0452 or P0453 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2008 Buick LaCrosse and 2008 Buick Allure. 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 X2-36 of the ECM.
  2. Disconnect the C405 harness connector at the rear of the fuel tank.
  3. Test for less than 5 ohms of resistance between the low reference circuit terminal H 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 X2-36 of the ECM.
  5. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal F and ground, at the ECM side of connector C405.
    • If less than the specified range, test the 5-volt reference circuit for a short to ground, or an 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 the scan tool FTP Sensor parameter is less than 4.8 volts
    • If greater than the specified range, test the signal circuit for a short to voltage. If the circuit/connections test normal, replace the ECM.
  7. At the ECM side of C405, install a 3A fused jumper wire between the signal circuit terminal G and the 5-volt reference circuit terminal F. Verify the scan tool 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 harness connector at the FTP sensor.
  10. Inspect the FTP sensor circuits in the fuel tank harness, between the FTP sensor connector and C405 for the following conditions:
    • Damaged wiring or terminals
    • Open circuits
    • Short to ground
    • Wire to wire short
    • If a condition is located, repair as necessary.
  11. If all circuits/connections test normal, replace the FTP sensor.
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