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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1996 (Engine Controls And Fuel - 3.5L - DTC P025A/P0300 To DTC P0700) >> DTC P0685, P0689, or P0690 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2009 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
    IMPORTANT: You must perform the Circuit/System Verification first.
  1. Ignition OFF, disconnect the powertrain relay, which is PWR/TRN relay 6.
  2. Ignition ON, verify that a test lamp does not illuminate between the ignition circuit terminal 87 and ground.
    • If the test lamp illuminates, test the ignition circuit for a short to voltage.
  3. Ignition OFF, verify that a test lamp illuminates between the B+ circuit terminal 85 and ground.
    • If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
  4. Verify that a test lamp illuminates between the B+ circuit terminal 30 and ground.
    • If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
  5. Disconnect the X1 harness connector at the ECM.
  6. Test for less than 2 ohms between ground and the ECM terminal 73 X1.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  7. Ignition ON, verify that a test lamp illuminates between connector terminal 19 X1 and ground.
    • If the test lamp does not illuminate, test the circuit for an open/high resistance and a short to ground. If the circuit tests normal and its fuse is open, replace the ECM.
  8. Ignition OFF, connect the harness connector at the ECM.
  9. Ignition ON, connect a jumper wire between the B+ circuit terminal 87 and the ignition circuit terminal 30. Verify that the EC Ignition Relay Feedback Signal parameter indicates B+ voltage.
    • If the parameter does not indicate B+ voltage, test the ignition circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
  10. Ignition OFF, allow the ECM to completely power down.
  11. Verify that a test lamp does not illuminate between the B+ circuit terminal 85 and the control circuit terminal 86.
    • If the test lamp illuminates, test the control circuit for a short to ground. If the circuit tests normal, replace the ECM.
  12. Remove the test lamp.
  13. Ignition ON, verify the scan tool EC Ign. Relay Ckt Short Volts Test Status parameter is OK.
    • If not the specified value, test the control circuit for a short to voltage. If the circuit tests normal, replace the ECM.
  14. Install a 3A fused jumper wire between the control circuit terminal 86 and the B+ circuit terminal 85. Verify the scan tool EC Ign. Relay Ckt Short Volts Test Status parameter is Fault.
    • If not the specified value, test the control circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
  15. If all circuits test normal, replace the powertrain relay.
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