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Home >> Chevrolet >> 2003 >> Chevy Express H2500 >> Repair and Diagnosis >> Body & Frame >> Body, Cab Control Systems >> Body Control System >> Diagnostic Information and Procedures >> DTC B1440: Monitored Ignition Switch Circuits Has Malfunctioned >> Circuit Description

Circuit Description

The body control module (BCM) is the power mode master responsible for sending ignition switch position information on the class 2 serial data link. The BCM monitors 3 discrete wires from the ignition switch contacts and the engine run flag (ERF) in order to determine the present power mode. The BCM communicates this power mode information to all class 2 modules on the class 2 serial data link. The following table represents correct BCM power mode data:

Fig 1: Correct Ignition Switch Inputs
G02422563Courtesy of GENERAL MOTORS CORP.
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