* The TBCM 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).
2. Ignition OFF, disconnect the harness connector of the trailer brake control module.
3. Ignition ON, test for greater than 11 V between the IGN 1 voltage circuit terminal 15 and ground.
锟斤拷 If less than the specified voltage, test the IGN 1 voltage circuit for a short to ground or an open/high resistance. If the circuit test normal
and the MISC - IGN fuse is open, test the signal circuit terminal 37 for a short to ground. If the circuit tests normal, test or replace the
RUN/CRANK relay.
4. If all the circuits test normal, replace the trailer brake control module.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* Relay Replacement (Attached to Wire Harness) (See: Power and Ground Distribution/Power Distribution Relay/Service and Repair/Relay
Replacement (Attached to Wire Harness))Relay Replacement (Within an Electrical Center) (See: Power and Ground Distribution/Power
Distribution Relay/Service and Repair/Relay Replacement (Within an Electrical Center))
* Control Module References (See: Testing and Inspection/Programming and Relearning) for TBCM replacement, setup, and programming
Gasoline Without LY6
DTC B3894 (Gasoline Without LY6)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
