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

Communications Network

Pinpoint Tests

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

Refer to Wiring Diagram Set 11, Grounds for schematic and connector information. Diagrams By Number

Refer to Wiring Diagram Set 13, Power Distribution/SJB for schematic and connector information. Diagrams By Number

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

Normal Operation

The Smart Junction Box (SJB) communicates with the scan tool through the Medium Speed Controller Area Network (MS-CAN). Circuits VDB06 (GY/OG) (MS-CAN +) and VDB07 (VT/OG) (MS-CAN -) provide the network connection to the SJB. The SJB shares the MS-CAN with the HVAC module, the Accessory Protocol Interface Module (APIM), the Audio Control Module (ACM), the Driver Seat Module (DSM), the Rear Entertainment Module (RETM), the Satellite Digital Audio Receiver System (SDARS) module, the Liftgate/Trunk Module (LTM) and the Instrument Cluster (IC). Voltage for the SJB is provided by redundant circuits. Fuse 5 (10A) provides voltage, and circuit GD133 (BK) provides ground.

This pinpoint test is intended to diagnose the following:

- Fuse
- Wiring, terminals or connectors
- SJB



PINPOINT TEST H: THE SJB 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.

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H1 CHECK THE SJB VOLTAGE SUPPLY CIRCUIT FOR AN OPEN


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




- Is the voltage greater than 10 volts?

Yes
GO to H2.

No
VERIFY the SJB fuse 5 (10A) is OK. If OK, GO to H4. If not OK, Refer to the Wiring Diagrams to identify the possible causes of the short circuit.

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H2 CHECK THE SJB GROUND CIRCUITS FOR AN OPEN


- Ignition OFF.
- Disconnect: SJB C2280d.
- Measure the resistance between the SJB, harness side and ground, as follows:









- Are the resistances less than 5 ohms?

Yes
GO to H3.

No
REPAIR the circuit in question. CLEAR the DTCs. REPEAT the network test with the scan tool.

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H3 CHECK THE MS-CAN CIRCUITS BETWEEN THE SJB AND THE DATA LINK CONNECTOR (DLC) FOR AN OPEN


- Disconnect: SJB C2280b.
- Measure the resistance between the SJB C2280b-37, circuit VDB06 (GY/OG), harness side and the DLC C251-3, circuit VDB06 (GY/OG), harness side.




- Measure the resistance between the SJB C2280b-38, circuit VDB07 (VT/OG), harness side and the DLC C251-11, circuit VDB07 (VT/OG), harness side.




- Are the resistances less than 5 ohms?

Yes
GO to H4.

No
REPAIR the circuit in question. CLEAR the DTCs. REPEAT the network test with the scan tool.

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H4 CHECK FOR CORRECT SJB OPERATION


- Disconnect all the SJB connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the SJB 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. 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.

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