Sunday, June 30, 2019

2019 Cadillac Truck Escalade AWD V8-6.2L Diagnostic Instructions Page 394


DTC B1441 01



- Device Ignition OFF, RUN, and CRANK Circuit Short to Battery



DTC B1441 06



- Device Ignition OFF, RUN, and CRANK Circuit Short to Ground or Open



Diagnostic Fault Information



Circuit/System Description



This vehicles power mode master (PMM) is the body control module (BCM). The ignition switch is a low current switch with multiple discrete



ignition switch signals to the PMM for determination of the power mode. The PMM receives the ignition switch signals, and additionally a reference



voltage signal from the BCM, through the ignition switch, and back to the BCM. There are redundancies within the PMM system that can allow



operation of certain subsystems when there are faults in the ignition switch circuits. Other information such as serial data input from other modules



and DTCs is also used to determine what power mode signals and information is transmitted by the PMM. The BCM logic uses all this information



to identify the operators desired power mode and activate specific discrete signals, and serial data messages for the operation of many different



subsystems as necessary. Other modules which have switched voltage inputs may operate in a default mode if the PMM serial data message does not



match what the individual module can see from its own connections.



The PMM will activate relays and other direct outputs of the PMM as needed according to the calculated power mode. Several relays controlled by



the BCM are switched ignition voltage outputs the are pass through circuits within the BCM directly from the ignition switch. If these circuits short



to ground, the fuse to the ignition switch will open.



Conditions for Running the DTC



Ignition switch is in the START position.



Conditions for Setting the DTC



B1441 01



Off/run/crank voltage circuit is shorted to voltage for more than 2 seconds.



B1441 06



Off/run/crank voltage circuit is open for more than 2 seconds.



Action Taken When the DTC Sets



* The BCM operates in a fail-safe power mode dependent on the last valid power mode detected and the state of the engine run flag data on the



GMLAN serial data communications circuits.



* The other modules on the vehicle operate in a fail-safe power mode dependent on the last valid power mode transmitted by the BCM and the



state of the engine run flag on the GMLAN serial data communications circuits.



Conditions for Clearing the DTC



* A current DTC clears when the malfunction is no longer present.



* A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.



Diagnostic Aids



* A short to ground in the accessory wakeup serial data circuit will cause an open fuse to the ignition switch. DTC U1814 should be current.



* A short to ground in the run/crank ignition 1 voltage circuit of the run crank relay will cause an open fuse to the ignition switch. DTC B1428



should be current.



* The power modes and controls are determined using BCM logic. Comparing the Body Control Module Power Mode data display parameters



listed in Circuit/System Verification will determine if there is a power mode fault.



Reference Information



Schematic Reference



* Body Control System Schematics (See: Body and Frame/Body Control Systems/Diagrams/Electrical Diagrams)



* Power Distribution Schematics (See: Diagrams/Electrical Diagrams/Starting and Charging/Power and Ground Distribution/System



Diagram/Power Distribution Schematics)

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