Pinpoint Test B: Without a Trailer Connected to the Vehicle and With the Ignition Key Turned to the RUN Position, the TBC Modul

Auxiliary Brake System - Trailer Brake Control (TBC) Module

Pinpoint Test B: Without a Trailer Connected to the Vehicle and With the Ignition Key Turned to the RUN Position, the TBC Module Display Does Not Light Up/Prove Out

NOTE: Carry out all pinpoint tests without a trailer connected to the vehicle.

Refer to Wiring Diagram Set 95, Trailer/Camper Adapter for schematic and connector information. Diagrams By Number

Normal Operation

The voltage supply to the Trailer Brake Control (TBC) module must be between 9 and 16 volts for TBC module wake up, prove out and operation. If the voltage falls below or goes above these parameters, the appropriate DTC will be set. The TBC module receives fused battery voltage from Battery Junction Box (BJB) fuse 17 (30A) along circuit SBB17 (RD) and fused ignition voltage from Smart Junction Box (SJB) fuse 33 (10A) along circuit CBP33 (WH/BN). The ground path for the TBC module is along circuit GD138 (BK/WH).

- DTC B1317 (Battery Voltage High) - If the battery voltage is greater than 16 volts for 200 ms or longer, the TBC module shuts off trailer brake output and then shuts down.
- DTC B1318 (Battery Voltage Low) - If the battery voltage is less than 9 volts for 200 ms or longer, the TBC module shuts off trailer brake output and then shuts down.

This pinpoint test is intended to diagnose the following:
- Fuse(s)
- Wiring, terminals or connectors
- Vehicle battery
- Vehicle charging system
- TBC module



PINPOINT TEST B: WITHOUT A TRAILER CONNECTED TO THE VEHICLE AND WITH THE IGNITION KEY IN THE RUN POSITION, THE TBC MODULE DISPLAY DOES NOT LIGHT UP/PROVE OUT

NOTICE: Use the Flex Probe Kit for all test connections to prevent damage to the wiring terminals. Do not use standard multi-meter probes.

NOTE: DTCs B1317, B1318 or B1676 can be set if the vehicle has been recently jump started, the battery has been recently charged or the battery has been discharged. The battery may become discharged due to excessive load(s) on the charging system from aftermarket accessories or if the battery has been left unattended with the accessories on.

B1-B4:

B4-B6: