Pinpoint Test E: DTC B1318

Auxiliary Brake System - Trailer Brake Control (TBC) Module

Pinpoint Test E: DTC B1318



Normal Operation

- DTC B1318 (Battery Voltage Low)- sets in the Trailer Brake Control (TBC) module when the TBC (Trailer Brake Control) module detects that battery voltage has dropped below 9 volts on the voltage supply circuit while not braking.

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors

- High circuit resistance

- TBC (Trailer Brake Control) module

PINPOINT TEST E : DTC B1318

NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.

NOTE: Failure to disconnect the battery when instructed will result in false resistance readings.

E1 RECHECK THE TBC (Trailer Brake Control) MODULE DTCs

- Ignition ON.

- Enter the following diagnostic mode on the scan tool: TBC (Trailer Brake Control) Module Self-Test.

- Clear the DTCs. Repeat the TBC (Trailer Brake Control) module self-test.

Is DTC B1318 still present?

Yes
GO to E2.

No
The system is operating normally at this time. The DTC may have been set due to a previous low battery voltage condition.

E2 CHECK FOR CHARGING SYSTEM DTCs IN THE PCM

- Enter the following diagnostic mode on the scan tool: PCM Self-Test.

- Carry out the PCM self-test.

- Retrieve the continuous memory DTCs from the PCM.

Is DTC P0620, P0622, P0625, P0626 or P065B set in the PCM?

Yes
REFER to Battery.

No
GO to E3.

E3 CHECK THE BATTERY CONDITION AND STATE OF CHARGE

- Check the battery condition and verify the battery is fully charged.

Is the battery OK and fully charged?

Yes
GO to E4.

No
REFER to Charging System.

E4 CHECK THE TBC (Trailer Brake Control) MODULE VOLTAGE SUPPLY

- Ignition OFF.

- Disconnect: TBC (Trailer Brake Control) Module C2142.

- Ignition ON.

- Measure the voltage between the TBC (Trailer Brake Control) module C2142-8, circuit SBB22 (BN/RD), harness side and ground.





Is the voltage within 0.2 volt of the recorded battery voltage?

Yes
GO to E5.

No
REPAIR circuit SBB22 (BN/RD) for high resistance. TEST the system for normal operation.

E5 CHECK THE TBC (Trailer Brake Control) MODULE GROUND CIRCUIT FOR HIGH RESISTANCE

- Ignition OFF.

- Disconnect: Negative Battery Cable.

- Measure the resistance between the TBC (Trailer Brake Control) module C2142-11, circuit GD115 (BK/GY), harness side and ground.





Is the resistance less than 5 ohms?

Yes
GO to E6.

No
REPAIR circuit GD115 (BK/GY) for high resistance. CLEAR the DTC. REPEAT the self-test.

E6 CHECK FOR CORRECT TBC (Trailer Brake Control) MODULE OPERATION

- Disconnect the TBC (Trailer Brake Control) Module connector.

- Check for:
- corrosion

- damaged pins

- pushed-out pins


- Connect the TBC (Trailer Brake Control) Module connector and make sure it seats correctly.

- Operate the system and verify the concern is still present.

Is the concern still present?

Yes
INSTALL a new TBC (Trailer Brake Control) module. REFER to Trailer Brake Control (TBC) Module . TEST the system for normal operation.

No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.