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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> External Pages >> Different car >> Section 508 (Engine Controls/Fuel - 5.3L, 6.0L, 6.2L - DTC P0420 To DTC P3449 And Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> DTC P0685, P0689, P0690, or P1682 >> Circuit/System Description

Circuit/System Description

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There are 2 ignition voltage circuits supplied to the engine control module (ECM). One is supplied by the powertrain relay and the other is supplied by the Run/Crank relay. The ECM monitors and compares the ignition voltage supplied by the 2 relays.

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