Pinpoint Test U: The Smart Junction Box (SJB) Does Not Respond To The Scan Tool

Communications Network

Pinpoint Test U: The Smart Junction Box (SJB) Does Not Respond To The Scan Tool

Refer to Wiring Diagram Set 10, Grounds for schematic and connector information. [1][2]Diagrams By Number

Refer to Wiring Diagram Set 13, Power Distribution/SJB 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 Smart Junction Box (SJB) 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

- SJB (Smart Junction Box)

PINPOINT TEST U : THE SJB (Smart Junction Box) 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.

U1 CHECK THE SJB (Smart Junction Box) VOLTAGE SUPPLY CIRCUIT FOR AN OPEN

- Ignition ON.

- NOTE: Measurements are taken with the fuses installed.
Measure the voltage between the SJB (Smart Junction Box) fuse 5 (10A) and ground.






Is the voltage greater than 10 volts?

Yes
GO to U2.

No
VERIFY the SJB (Smart Junction Box) fuse 5 (10A) is OK. If OK, REPAIR the circuit. CLEAR the DTCs. REPEAT the network test with the scan tool. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. [1][2]Diagrams By Number

U2 CHECK THE SJB (Smart Junction Box) GROUND CIRCUIT FOR AN OPEN

- Ignition OFF.

- Disconnect: Negative Battery Cable.

- Disconnect: SJB (Smart Junction Box) C2280D.

- Measure the resistance between the SJB (Smart Junction Box) C2280D-8, circuit GD126 (BK/WH), harness side and ground; and between the SJB (Smart Junction Box) C2280D-12, circuit GD126 (BK/WH), harness side and ground.





Are the resistances less than 5 ohms?

Yes
GO to U3.

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

U3 CHECK THE MS-CAN (Medium Speed Controller Area Network) CIRCUITS BETWEEN THE SJB (Smart Junction Box) AND THE DLC (Data Link Connector) FOR AN OPEN

- Disconnect: SJB (Smart Junction Box) C2280B.

- Measure the resistance between the SJB (Smart Junction Box) C2280B-37, circuit VDB06 (GY/OG), harness side and the DLC (Data Link Connector) C251-3, circuit VDB06 (GY/OG), harness side.





- Measure the resistance between the SJB (Smart Junction Box) C2280B-38, 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 U4.

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

U4 CHECK FOR CORRECT SJB (Smart Junction Box) OPERATION

- Disconnect all the SJB (Smart Junction Box) connectors.

- Check for:
- corrosion

- damaged pins

- pushed-out pins


- Connect all the SJB (Smart Junction Box) 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 SJB (Smart Junction Box). 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 DTCs. REPEAT the network test with the scan tool.