Pinpoint Test D: The Smart Junction Box (SJB) Does Not Respond To The Scan Tool
Communications Network
Pinpoint Tests
Pinpoint Test D: The Smart Junction Box (SJB) Does Not Respond To The Scan Tool
Refer to Wiring Diagram Set 10, 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 1847 (WH/OG) (MS-CAN +) and 1848 (PK/OG) (MS-CAN -) provide the network connection to the SJB. The SJB shares the MS-CAN with the Audio Control Module (ACM), the Satellite Digital Audio Receiver System (SDARS) module (if equipped) and the Instrument Cluster (IC). Voltage for the SJB is provided by circuits 905 (GY/LB), 1052 (TN/BK) and 1523 (DG). Both circuits 1205 (BK) provide ground.
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- SJB
PINPOINT TEST D: 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.
NOTE: Failure to disconnect the battery when instructed will result in false resistance readings. Refer to Battery.
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D1 CHECK THE MS-CAN TERMINATION RESISTANCE
- Ignition OFF.
- Disconnect: Negative Battery Cable.
- Measure the resistance between the DLC C251-3, circuit 1847 (WH/OG), harness side and the DLC C251-11, circuit 1848 (PK/OG), harness side.
- Is the resistance between 54 and 66 ohms?
Yes
GO to D3.
No
GO to D2.
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D2 CHECK THE MS-CAN CIRCUITS BETWEEN THE SJB AND THE DLC FOR AN OPEN
- Disconnect: SJB C2280b.
- Measure the resistance between the SJB C2280b-50, circuit 1847 (WH/OG), harness side and the Data Link Connector (DLC) C251-3, circuit 1847 (WH/OG), harness side.
- Measure the resistance between the SJB C2280b-51, circuit 1848 (PK/OG), harness side and the DLC C251-11, circuit 1848 (PK/OG), harness side.
- Are the resistances less than 5 ohms?
Yes
GO to D3.
No
REPAIR the circuit in question. CLEAR the DTCs. REPEAT the network test with the scan tool.
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D3 CHECK THE SJB VOLTAGE SUPPLY CIRCUITS FOR AN OPEN
- Ignition OFF.
- Disconnect: SJB C2280h.
- Connect: Negative Battery Cable.
- Ignition ON.
- Measure the voltage between the SJB, harness side and ground as follows:
- Are the voltages greater than 10 volts?
Yes
GO to D4.
No
VERIFY the Bussed Electrical Center (BEC) fuse(s) 59 (30A), 63 (30A) and 67 (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 short circuit. CLEAR the DTCs. REPEAT the network test with the scan tool.
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D4 CHECK THE SJB GROUND CIRCUITS FOR AN OPEN
- Ignition OFF.
- Measure the resistance between the SJB C2280h-8, circuit 1205 (BK), harness side and ground; and between the SJB C2280h-22, circuit 1205 (BK), harness side and ground.
- Are the resistances less than 5 ohms?
Yes
CONNECT the negative battery cable. GO to D5.
No
REPAIR the circuit in question. CONNECT the negative battery cable. CLEAR the DTCs. REPEAT the network test with the scan tool.
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D5 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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