Pinpoint Test G: The Body Control Module B (BCM-B) Does Not Respond To The Scan Tool

Communications Network

Pinpoint Test G: The Body Control Module B (BCM-B) Does Not Respond To The Scan Tool

Refer to Wiring Diagram Set 89, Interior Lamps for schematic and connector information [1][2]Diagrams By Number.

Refer to Wiring Diagram Set 14, Module Communications Network for schematic and connector information [1][2]Diagrams By Number.

Normal Operation

The Body Control Module B (BCM-B) communicates with the scan tool through the Medium Speed Controller Area Network (MS-CAN).

This pinpoint test is intended to diagnose the following:

- Fuse

- Wiring, terminals or connectors

- BCM-B (Body Control Module B)

PINPOINT TEST G : THE BCM-B (Body Control Module B) 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 results in false resistance readings.

G1 CHECK THE BCM-B (Body Control Module B) VOLTAGE SUPPLY CIRCUITS FOR AN OPEN

- Ignition OFF.

- Disconnect: BCM-B (Body Control Module B) C4368A.

- Ignition ON.

- Measure the voltage between the BCM-B (Body Control Module B) C4368A-1, circuit SBB18 (YE/RD), harness side and ground; and between the BCM-B (Body Control Module B) C4368A-7, circuit CBP35 (YE/GY), harness side and ground.





Are the voltages greater than 10 volts?

Yes
GO to G2.

No
VERIFY the Battery Junction Box (BJB) fuse 18 (20A) or Smart Junction Box (SJB) fuse 35 (10A) is 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 [1][2]Diagrams By Number. CLEAR the DTCs. REPEAT the network test with the scan tool.

G2 CHECK THE BCM-B (Body Control Module B) GROUND CIRCUIT FOR AN OPEN

- Ignition OFF.

- Disconnect: Negative Battery Cable.

- Measure the resistance between the BCM-B (Body Control Module B) C4368A-13, circuit GD110 (BK/WH), harness side and ground.





Is the resistance less than 5 ohms?

Yes
GO to G3.

No
REPAIR the circuit. CONNECT the negative battery cable. CLEAR the DTCs. REPEAT the network test with the scan tool.

G3 CHECK THE MS-CAN (Medium Speed Controller Area Network) CIRCUITS BETWEEN THE BCM-B (Body Control Module B) AND THE DLC (Data Link Connector) FOR AN OPEN

- Measure the resistance between the BCM-B (Body Control Module B) C4368A-11, circuit VDB06 (GY/OG), harness side and the Data Link Connector (DLC) C251-3, circuit VDB06 (GY/OG), harness side.





- Measure the resistance between the BCM-B (Body Control Module B) C4368A-23, circuit VDB07 (VT/OG), harness side and the DLC (Data Link Connector) C251-11, circuit VDB07 (VT/OG), harness side.





Are the resistances less than 5 ohms?

Yes
CONNECT the negative battery cable. GO to G4.

No
REPAIR the circuit in question. CONNECT the negative battery cable. CLEAR the DTCs. REPEAT the network test with the scan tool.

G4 CHECK FOR CORRECT BCM-B (Body Control Module B) OPERATION

- Disconnect all the BCM-B (Body Control Module B) connectors.

- Check for:
- corrosion

- damaged pins

- pushed-out pins


- Connect all the BCM-B (Body Control Module B) 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 BCM-B (Body Control Module B). 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. CLEAR the DTCs. REPEAT the network test with the scan tool.