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Home >> Buick >> 2006 >> Lucerne CX >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - 3.8L - DTC P0453 To DTC P2135 >> 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:
    • The ETC fuse
    • The Emission fuse
    • The ELEK Ign fuse
    • The Fuel Inj. fuse
    • The O2 SSR 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.
  3. Ignition OFF, observe the Ignition 1 Voltage Signal parameter. The parameter should be 0 volt before the PCM powers down.
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