Trailer Brake Control System: Other Chevrolet Silverado 2500 HD

Reference Information

Schematic Reference

Trailer Brake Control Schematics

Description and Operation

Trailer Brake Controls Description and Operation

Connector End View Reference

1. «Trailer Brake Control Connector End Views»(ref-278041-S37661071012008012100000)
2. «Engine Control Module Connector End Views»(ref-278009-S25375154122008012100000)

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

1. «Scan Tool Output Controls»(ref-278041-S36451619802008012100000)
2. «Scan Tool Data List»(ref-278041-S05174227092008012100000)

Circuit/System Verification

Ignition ON, press the brake pedal. The brake lights should illuminate, and scan tool data list Brake Switch Status should indicate ON.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for TBCM replacement, setup, and programming

Schematic Reference

Trailer Brake Control Schematics

Connector End View Reference

Trailer Brake Control Connector End Views

Description and Operation

Trailer Brake Controls Description and Operation

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for TBCM replacement, setup, and programming

C056D

The Ignition is ON, and DTC C056D runs once an ignition cycle.

C056E

The ignition is ON, with the engine OFF, DTC C056D runs continuously.

The TBCM detected a failure in its microprocessor.

The TBCM is not programmed.

Schematic Reference

Trailer Brake Control Schematics

Connector End View Reference

Trailer Brake Control Connector End Views

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

Scan Tool Reference

1. «Scan Tool Output Controls»(ref-278041-S36451619802008012100000)
2. «Scan Tool Data List»(ref-278041-S05174227092008012100000)

Ignition ON, observe the DTC information with a scan tool. DTC C056D and DTC C056E, should not set.

1. If DTC C056D failed this ignition, replace the TBCM.

1. If DTC C056E failed this ignition, program the TBCM.

Program the TBCM. If DTC C056E sets after programming, perform the following steps

1. If DTC C056D is set, turn off the ignition, wait 30 seconds, turn ignition on, if DTC C056D failed this ignition cycle, replace the TBCM.
2. If DTC C056E is set, turn off the ignition, wait 30 seconds, turn ignition on, if DTC C056E failed this ignition cycle, program the TBCM. If DTC C056E sets after programming, replace the TBCM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for TBCM replacement, setup, and programming

Schematic Reference

Trailer Brake Control Schematics

Description and Operation

Trailer Brake Controls Description and Operation

Connector End View Reference

1. «Trailer Brake Control Connector End Views»(ref-278041-S37661071012008012100000)
2. «Engine Control Module Connector End Views»(ref-278009-S25375154122008012100000)

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

Scan Tool Reference

1. «Scan Tool Output Controls»(ref-278041-S36451619802008012100000)
2. «Scan Tool Data List»(ref-278041-S05174227092008012100000)

With the scan tool installed, ignition ON and the engine running, observe the Battery Positive Voltage parameter in the TBCM data list. The reading should be between 9-17 volts.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for TBCM replacement, setup, and programming

Schematic Reference

Trailer Brake Control Schematics

Description and Operation

Trailer Brake Controls Description and Operation

Connector End View Reference

1. «Trailer Brake Control Connector End Views»(ref-278041-S37661071012008012100000)
2. «Engine Control Module Connector End Views»(ref-278009-S25375154122008012100000)

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

Scan Tool Reference

1. «Scan Tool Output Controls»(ref-278041-S36451619802008012100000)
2. «Scan Tool Data List»(ref-278041-S05174227092008012100000)

Schematic Reference

Trailer Brake Control Schematics

Description and Operation

Trailer Brake Controls Description and Operation

Connector End View Reference

1. «Trailer Brake Control Connector End Views»(ref-278041-S37661071012008012100000)
2. «Engine Control Module Connector End Views»(ref-278009-S25375154122008012100000)

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

Scan Tool Reference

1. «Scan Tool Output Controls»(ref-278041-S36451619802008012100000)
2. «Scan Tool Data List»(ref-278041-S05174227092008012100000)

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for TBCM replacement, setup, and programming

Schematic Reference

Trailer Brake Control Schematics

Description and Operation

Trailer Brake Controls Description and Operation

Connector End View Reference

1. «Trailer Brake Control Connector End Views»(ref-278041-S37661071012008012100000)
2. «Engine Control Module Connector End Views»(ref-278009-S25375154122008012100000)

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

Scan Tool Reference

1. «Scan Tool Output Controls»(ref-278041-S36451619802008012100000)
2. «Scan Tool Data List»(ref-278041-S05174227092008012100000)

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for TBCM replacement, setup, and programming

Schematic Reference

Trailer Brake Control Schematics

Description and Operation

Trailer Brake Controls Description and Operation

Connector End View Reference

1. «Trailer Brake Control Connector End Views»(ref-278041-S37661071012008012100000)
2. «Engine Control Module Connector End Views»(ref-278009-S25375154122008012100000)

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

1. «Scan Tool Output Controls»(ref-278041-S36451619802008012100000)
2. «Scan Tool Data List»(ref-278041-S05174227092008012100000)

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for TBCM replacement, setup, and programming

Schematic Reference

Trailer Brake Control Schematics

Description and Operation

Trailer Brake Controls Description and Operation

Connector End View Reference

Trailer Brake Control Connector End Views

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

Scan Tool Reference

1. «Scan Tool Output Controls»(ref-278041-S36451619802008012100000)
2. «Scan Tool Data List»(ref-278041-S05174227092008012100000)

1. Ignition ON, observe the scan tool brake controls Trailer Brake Relay Status parameter. The reading should be Enabled or Disabled.
2. Ignition ON, observe the scan tool brake controls TBCM Command Duty Cycle parameter. The reading should be 0-100 percent.

Perform the Diagnostic Repair Verification

1. «Trailer Brake Control Module Replacement»(ref-278041-S14765524632008012100000)
2. «Control Module References»(ref-278020-S09054666032008012100000)

Schematic Reference

Trailer Brake Control Schematics

Description and Operation

Trailer Brake Controls Description and Operation

Connector End View Reference

Trailer Brake Control Connector End Views

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

Scan Tool Reference

1. «Scan Tool Output Controls»(ref-278041-S36451619802008012100000)
2. «Scan Tool Data List»(ref-278041-S05174227092008012100000)

1. Ignition ON, observe the scan tool brake controls Trailer Brake Relay Status parameter. The reading should be Enabled or Disabled.
2. Ignition ON, observe the scan tool brake controls TBCM Command Duty Cycle parameter. The reading should be 0-100 percent.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Trailer Brake Control Module Replacement»(ref-278041-S14765524632008012100000)
2. «Control Module References»(ref-278020-S09054666032008012100000) for TBCM replacement, setup, and programming

Schematic Reference

Trailer Brake Control Schematics

Description and Operation

Trailer Brake Controls Description and Operation

Connector End View Reference

Trailer Brake Control Connector End Views

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

Scan Tool Reference

1. «Scan Tool Output Controls»(ref-278041-S36451619802008012100000)
2. «Scan Tool Data List»(ref-278041-S05174227092008012100000)

1. Ignition ON, observe the scan tool brake controls Trailer Brake Relay Status parameter. The reading should be Enabled or Disabled.
2. Ignition ON, observe the scan tool brake controls TBCM Command Duty Cycle parameter. The reading should be 0-100 percent.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Trailer Brake Control Module Replacement»(ref-278041-S14765524632008012100000)
2. «Control Module References»(ref-278020-S09054666032008012100000) for TBCM replacement, setup, and programming

Schematic Reference

Trailer Brake Control Schematics

Description and Operation

Trailer Brake Controls Description and Operation

Connector End View Reference

Trailer Brake Control Connector End Views

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

Scan Tool Reference

1. «Scan Tool Output Controls»(ref-278041-S36451619802008012100000)
2. «Scan Tool Data List»(ref-278041-S05174227092008012100000)

1. Ignition ON, observe the scan tool brake controls Primary Manual Apply parameter. The reading should be between 0-100 percent and change with brake pedal input.
2. Ignition ON, observe the scan tool brake controls Redundant Manual Apply parameter. The reading should be between 0-100 percent and change with brake pedal input.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Control Module References»(ref-278020-S09054666032008012100000) for TBCM replacement, setup, and programming
2. «Trailer Brake Control Module Replacement»(ref-278041-S14765524632008012100000)

Schematic Reference

Trailer Brake Control Schematics

Description and Operation

Trailer Brake Controls Description and Operation

Connector End View Reference

Trailer Brake Control Connector End Views

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

Scan Tool Reference

1. «Scan Tool Output Controls»(ref-278041-S36451619802008012100000)
2. «Scan Tool Data List»(ref-278041-S05174227092008012100000)

1. Ignition ON, observe the scan tool brake controls Primary Manual Apply parameter. The reading should be between 0-100 percent and change with brake pedal input.
2. Ignition ON, observe the scan tool brake controls Redundant Manual Apply parameter. The reading should be between 0-100 percent and change with brake pedal input.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Control Module References»(ref-278020-S09054666032008012100000) for TBCM replacement, setup, and programming
2. «Trailer Brake Control Module Replacement»(ref-278041-S14765524632008012100000)

Schematic Reference

Trailer Brake Control Schematics

Description and Operation

Trailer Brake Controls Description and Operation

Connector End View Reference

Trailer Brake Control Connector End Views

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

Scan Tool Reference

1. «Scan Tool Output Controls»(ref-278041-S36451619802008012100000)
2. «Scan Tool Data List»(ref-278041-S05174227092008012100000)

1. Ignition ON, observe the scan tool brake controls Primary Manual Apply parameter. The reading should be between 0-100 percent and change with brake pedal input.
2. Ignition ON, observe the scan tool brake controls Redundant Manual Apply parameter. The reading should be between 0-100 percent and change with brake pedal input.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Control Module References»(ref-278020-S09054666032008012100000) for TBCM replacement, setup, and programming
2. «Trailer Brake Control Module Replacement»(ref-278041-S14765524632008012100000)

Schematic Reference

Trailer Brake Control Schematics

Description and Operation

Trailer Brake Controls Description and Operation

Connector End View Reference

Trailer Brake Control Connector End Views

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

Scan Tool Reference

1. «Scan Tool Output Controls»(ref-278041-S36451619802008012100000)
2. «Scan Tool Data List»(ref-278041-S05174227092008012100000)

1. Ignition ON, observe the scan tool trailer brake controls user gain parameter. The reading should be between 0-100 percent, and change with operating the gain switch up or gain switch down.
2. The reading should be between 0-100 percent, and change with operating the gain switch up or gain switch down.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Control Module References»(ref-278020-S09054666032008012100000) for TBCM replacement, setup, and programming
2. «Trailer Brake Control Module Replacement»(ref-278041-S14765524632008012100000)

Schematic Reference

Trailer Brake Control Schematics

Description and Operation

Trailer Brake Controls Description and Operation

Connector End View Reference

Trailer Brake Control Connector End Views

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

Scan Tool Reference

1. «Scan Tool Output Controls»(ref-278041-S36451619802008012100000)
2. «Scan Tool Data List»(ref-278041-S05174227092008012100000)

1. Ignition ON, observe the scan tool brake controls TBCM Relay Feedback Signal volts parameter. The reading should be between 4.8-5.2 volts.
2. Ignition ON, observe the scan tool brake controls Trailer Brake Relay Command volts parameter. The reading should be battery volts.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Trailer Brake Control Module Replacement»(ref-278041-S14765524632008012100000)
2. «Control Module References»(ref-278020-S09054666032008012100000) for TBCM replacement, setup, and programming

Symptoms - Trailer Brake Controls

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections .

Manual Trailer Brake Apply

The Manual Trailer Brake Apply Lever is located on the Trailer Brake Control Panel, and is used to apply the trailer electric brakes independent of your vehicle brakes. This lever is used in the Trailer Gain Adjustment Procedure to properly adjust the power output to the trailer brakes. Sliding the lever to the left will apply only the trailer brakes. The power output to the trailer is indicated in the Trailer Brake Display Page in the DIC. If your vehicle service brakes are applied while using the Manual Trailer Brake Apply Lever, the trailer output power will be the greater of the two.

The trailer and the vehicle brake lamps will come on when either vehicle braking or manual trailer brakes are applied.

Trailer Brake Control Panel

The TBCM system has a control panel with the trailer gain and manual apply switches, and is located on the instrument panel to the left of the steering column. See Instrument Panel Overview for more information on location. The control panel and switches allows you to adjust the amount of output, referred to as trailer gain, available to the electric trailer brakes and allows you to manually apply the trailer brakes. The Trailer Brake Control Panel, and switches is used along with the Trailer Brake Display Page on the DIC to adjust and display power output to the trailer brakes.

Driver Information Indicators and Messages

The following indicators are used to inform the driver of several different factors.

TRAILER CONNECTED

This message will be briefly displayed when a trailer with electric brakes is first connected to the vehicle. This message will automatically turn off in about ten seconds. The driver can also acknowledge this message before it automatically turns off.

SERVICE TRAILER BRAKE SYSTEM

This message will be displayed when there is a problem with the TBCM system. If this message persists over multiple ignition cycles there is problem with the TBCM system. Take your vehicle to an authorized GM dealer to have the TBCM system diagnosed and repaired.

TRAILER GAIN and OUTPUT Display

This display menu can be accessed by scrolling through the DIC vehicle Information menu, or any time the trailer gain +/- button is depressed, or the manual trailer brake apply lever is actuated. The trailer gain display is 0 to 10 in 0.5 step increments, and indicates the current user setting of the trailer output gain. The trailer output is 0 to 10 bars in 1 bar increments, and indicates the output power provided to the trailer brakes, relative to the gain setting.