DTC B1440: Power Mode Master Input Circuit Mismatch: Description

WARNING: This page is about a different car, the 2002 Chevrolet Monte Carlo, 2002 Chevrolet Impala, 2001 Chevrolet Monte Carlo, and 2001 Chevrolet Impala. However, it is still accessible from the selected car via links, so may be relevant.

Body Control Module (BCM) monitors Ignition 0, Ignition 1 and accessory signals from ignition switch. BCM uses voltage state (battery voltage or 0) and sequence of state changes to determine power mode called for by ignition switch. DTC B1440 is set when one of ignition switch circuits is shorted to either battery voltage or ground. Sequence of change of circuit is incorrect for expected power mode.

When DTC B1440 is set, BCM stores DTC B1440 to memory. BCM operates in a fail-safe power mode dependent on last valid power mode detected and state of engine run flag data on class 2 serial data communications circuits. Other modules on vehicle operate in a fail safe power mode dependent on last valid power mode transmitted by BCM and state of engine run flag on class 2 serial data communications circuits.

Current DTC B1440 will clear and become a history DTC when BCM detects a sequence of ignition switch inputs that match expected power mode. History DTC will clear after 100 ignition cycles with no repeated malfunction.