Communications Network

COMMUNICATIONS NETWORK

NOTE:The smart junction box (SJB) is also known as the generic electronic module (GEM).

Inspection and Verification

1. Verify the customer concern.

2. Visually inspect the following for obvious signs of electrical damage.





3. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.

4.
NOTE:Make sure to use the latest IDS or equivalent tester software release.If the cause is not visually evident, connect the IDS or equivalent tester to the DLC.
NOTE:The vehicle communication module (VCM) LED prove-out confirms power and ground from the DLC are provided to the VCM.
If the IDS or equivalent tester does not communicate with the VCM:

- Check the VCM connection to the vehicle.
- Check the IDS or equivalent tester connection to the VCM.
- See - Pinpoint Test 7: No Module/Network Communication - No Power To The Diagnostic Tool, to diagnose no power to the IDS or equivalent tester.

5.
NOTE:During the network test, the IDS or equivalent tester will first attempt to communicate with the PCM, after establishing communication with the PCM, the IDS or equivalent tester will then attempt to communicate with all other modules on the vehicle.Carry out the network test.

- If the network test passes, retrieve and record the continuous memory DTCs and proceed to Step 6.
- If the network test fails, see - Symptom Troubleshooting Chart - Communications Networkto identify the module not communicating.

6. If the DTCs retrieved are related to the concern, go to that module's Diagnostic Trouble Code (DTC) Index. For all other DTCs, see - Diagnostic Trouble Code (DTC) Index - B, C And U Codes.

7. If no DTCs related to the concern are retrieved, see - Symptom Troubleshooting Chart - Communications Network.