DTC Descriptor
DTC B3894 5A
- Stop Lamp Switch Circuit Plausibility Failure
Circuit/System Description
The brake switch is hard wired to the fuel pump/trailer brake control module. The body control module (BCM) sends a brake switch status serial
data message to the fuel pump/trailer brake control module. The fuel pump/trailer brake control module compares the states of the brake switch
signal to the serial data message after a master cylinder brake pressure sensor threshold is exceeded. If the brake switch signal and the serial data
message are not in agreement or if the serial data message is not valid, a DTC will set and the trailer brake control system will be disabled.
Conditions for Running the DTC
* Battery voltage is 9.5-17 V.
* The module initialization has taken place.
* The master cylinder brake pressure exceeds threshold
Conditions for Setting the DTC
* The brake switch serial data message is not valid.
* The actual brake switch input to the fuel pump/trailer brake control module, and the serial data information for the brake switch do not match.
Action Taken When the DTC Sets
* The trailer brake control will be disabled for the remainder of the ignition cycle.
* The driver information center (DIC) will display Service Trailer Brake System.
Conditions for Clearing the DTC
* The condition for the DTC is no longer present.
* The fuel pump/trailer brake control module clears the history DTC when a current DTC is not detected in 40 consecutive drive cycles.
Reference Information
Schematic Reference
Trailer Brake Control Schematics (See: Brakes and Traction Control/Diagrams/Electrical Diagrams)
Connector End View Reference
Component Connector End Views (See: Diagrams/Connector Views)
Description and Operation
Trailer Brake Controls Description and Operation (See: Powertrain Management/Computers and Control Systems/Description and
Operation/Trailer Brake Controls Description and Operation)
Electrical Information Reference
* Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Circuit
Testing/Circuit Testing)
* Connector Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Connector Repairs/Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (See: Testing and Inspection/Component Tests and General Diagnostics/General
Electrical Diagnostic Procedures/Circuit Testing/Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Wiring
Repairs/Wiring Repairs)
Scan Tool Reference
Control Module References (See: Testing and Inspection/Programming and Relearning) for scan tool information
Circuit/System Verification
Ignition ON, press the brake pedal. The brake lights should illuminate and the Brake Switch Status parameter should indicate ON.
Circuit/System Testing
1. Verify that DTC B3445, C0277, C0297, or C0890 are not set.
锟斤拷 If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle (See: Diagnostic Trouble Code
Descriptions/Diagnostic Trouble Code (DTC) List - Vehicle).
