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Home >> Buick >> 2006 >> Allure CX >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - 3.8L - DTC P0451 To DTC P2120 >> DTC P0685 >> Circuit/System Verification
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Circuit/System Verification

  1. With the ignition ON, engine OFF, command the powertrain relay ON and OFF several times using the scan tool output control function. You should either hear or feel the relay click with each command.
  2. With the ignition ON, engine OFF, probe both test points of each of the following fuses:
    • ETC Fuse
    • Emission 1 Fuse
    • The test lamp should illuminate on at least one test point of each fuse. If the test lamp does not illuminate continue with Circuit/System Testing.