Pinpoint Test E: The Trailer Brake Control (TBC) Module Does Not Respond To The Scan Tool
Communications Network
Pinpoint Tests
Pinpoint Test E: The Trailer Brake Control (TBC) Module Does Not Respond To The Scan Tool
Normal Operation
The Trailer Brake Control (TBC) module is optional equipment. The TBC module communicates with the scan tool through the High Speed Controller Area Network (HS-CAN). Circuits VDB04 (WH/BU) (HS-CAN +) and VDB05 (WH) (HS-CAN -) provide the network connection to the TBC module. Voltage for the TBC module is provided by circuits CBP33 (WH/BN) and SBB18 (YE/RD). Ground is provided by circuit GD116 (BK/VT).
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Trailer Brake Control (TBC) module
PINPOINT TEST E: THE TBC MODULE DOES NOT RESPOND TO THE SCAN TOOL
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. Refer to Battery.
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E1 CHECK THE TBC MODULE POWER SUPPLY CIRCUITS FOR AN OPEN
- Ignition OFF.
- Disconnect: TBC Module C2142.
- Ignition ON.
- For vehicles equipped with a telematics module, measure the voltage between the TBC module C2142-8, circuit VB-A (GY/RD), harness side and ground; and between the TBC module C2142-12, circuit IGRUN-A (WH/BN), harness side and ground.
- For vehicles not equipped with a telematics module, measure the voltage between the TBC module C2142-8, circuit SBB18 (YE/RD), harness side and ground; and between the TBC module C2142-12, circuit CBP33 (WH/BN), harness side and ground.
- Are the voltages greater than 10 volts?
Yes
GO to E2.
No
VERIFY the Smart Junction Box (SJB) fuse 33 (10A) and Battery Junction Box (BJB) fuse 18 (30A) are OK. If OK, REPAIR the circuit in question. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. CLEAR the DTCs. REPEAT the network test with the scan tool.
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E2 CHECK THE TBC MODULE GROUND CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: Negative Battery Cable.
- For vehicles equipped with a telematics module, measure the resistance between the TBC module C2124-11, circuit GND-A (BK/GY), harness side and ground.
- For vehicles not equipped with a telematics module, measure the resistance between the TBC module C2124-11, circuit GD116 (BK/VT), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to E3.
No
REPAIR the circuit. CONNECT the negative battery cable. CLEAR the DTCs. REPEAT the network test with the scan tool.
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E3 CHECK THE HS-CAN CIRCUITS BETWEEN THE TBC MODULE AND THE DLC FOR AN OPEN
- For vehicles equipped with a telematics module, measure the resistance between the TBC module C2142-2, circuit VDB04 (WH/BU), harness side and the Data Link Connector (DLC) C251-6, circuit HSC1-A (WH/BU), harness side.
- For vehicles not equipped with a telematics module, measure the resistance between the TBC module C2142-2, circuit VDB04 (WH/BU), harness side and the DLC C251-6, circuit VDB04 (WH/BU), harness side.
- For vehicles equipped with a telematics module, measure the resistance between the TBC module C2142-3, circuit VDB05 (WH), harness side and the DLC C251-14, circuit HSC2-A (WH), harness side.
- For vehicles not equipped with a telematics module, measure the resistance between the TBC module C2142-3, circuit VDB05 (WH), harness side and the DLC C251-14, circuit VDB05 (WH), harness side.
- Are the resistances less than 5 ohms?
Yes
CONNECT the negative battery cable. GO to E4.
No
REPAIR the circuit in question. CONNECT the negative battery cable. REPEAT the network test with the scan tool.
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E4 CHECK FOR CORRECT TBC MODULE OPERATION
- Disconnect all the TBC module connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the TBC module connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
Yes
INSTALL a new TBC module. CLEAR the DTCs. REPEAT the network test with the scan tool.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the diagnostic trouble codes (DTCs). REPEAT the network test with the scan tool.
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