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Home >> GMC >> 2018 >> Terrain Denali, FWD >> Repair and Diagnosis >> Body & Frame >> Ignition Switch/Steering Lock >> Immobilizer System >> Diagnostic Information And Procedures >> DTC P1649: Immobilizer Security Code Not Programmed >> Circuit/System Description
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Circuit/System Description

When learning the security code, as well as the challenge and response sequence, the engine control module (ECM) is placed in learn mode. Once the security code and challenge/response are learned, learn mode will be exited when the engine is successfully started.