9-7X L6-4.2L (2008)
Circuit/System Description
Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Operating information and
commands are exchanged among the modules. Connecting a scan tool to the data link connector (DLC) allows communication with the modules for
diagnostic purposes. DTCs may be set due to this symptom and during this diagnostic procedure. Complete the diagnostic procedure in order to ensure
all the DTCs are diagnosed and cleared from memory.
Diagnostic Aids
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The body control module (BCM) detects that the ignition is ON and sends the appropriate power mode message to the other modules. Therefore,
the BCM must be connected to the DLC for any other module to communicate with the scan tool.
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This test is used for a total class 2 serial data communication failure. If only one module is not communicating and sets no DTC, ensure that the
vehicle is equipped with the module, then use DTC U1001-U1254 (See: Testing and Inspection/Diagnostic Trouble Code Tests and Associated
Procedures/U Code Charts/U1001) for diagnostics.
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The following conditions may cause a total loss of class 2 serial data communication:
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The class 2 serial data circuit shorted to ground or voltage.
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A module internal malfunction that causes a short to voltage or ground on the class 2 serial data circuit.
Reference Information
Schematic Reference
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Data Communication Schematics (See: Diagrams/Electrical Diagrams)
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Control Module References (See: Testing and Inspection/Programming and Relearning/Control Module References)
Connector End View Reference
Component Connector End Views (See: Diagrams/Connector Views/Component Connector End Views)
Description and Operation
Data Link Communications Description and Operation (See: Description and Operation)
Electrical Information Reference
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Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics/Circuit Testing/Circuit Testing)
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Connector Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/Connector Repairs/Connector Repairs)
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Testing for Intermittent Conditions and Poor Connections (See: Testing and Inspection/Component Tests and General Diagnostics/Circuit
Testing/Testing for Intermittent Conditions and Poor Connections)
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Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/Wiring Repairs/Wiring Repairs)
Scan Tool Reference
Control Module References (See: Testing and Inspection/Programming and Relearning/Control Module References) for Scan Tool Information
Circuit/System Testing
Class 2 Communication Initial Test
1. Test for less than 1 ohm between the DLC ground circuit terminal 5 and ground.
‹› If greater than the specified range, test the ground circuit for open/high resistance.
2. Ignition OFF, disconnect the harness connector of JX305 and attempt to communicate with the BCM. Communication should not be available.
‹› If communication is available, refer to JX305 Test.
3. Ignition OFF, disconnect the harness connector of JX205.
