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Home >> Hummer >> 2009 >> H3T Base, Standard >> Repair and Diagnosis >> Body & Frame >> Ignition Switch/Steering Lock >> Immobilizer System >> Diagnostic Information and Procedures >> DTC P1631 >> Circuit/System Description
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Circuit/System Description

The body control module (BCM) sends the fuel enable password to the engine control module (ECM) via the serial data circuit. The ECM compares this password to the learned password. If the learned password matches the password received from the BCM, the ECM will allow vehicle starting.