Communications Network

Communications Network

Inspection and Verification

1. Verify the customer concern.

2. Visually inspect for obvious signs of electrical damage.

Visual Inspection Chart






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 scan tool software release.

If the cause is not visually evident, connect the scan tool to the DLC (Data Link Connector).

NOTE: The Vehicle Communication Module (VCM) LED prove-out confirms power and ground from the DLC (Data Link Connector) are provided to the VCM (Vehicle Communication Module).

If the scan tool does not communicate with the VCM (Vehicle Communication Module) :

- Check the VCM (Vehicle Communication Module) connection to the vehicle.

- Check the scan tool connection to the VCM (Vehicle Communication Module).

- GO to Pinpoint Test AE, to diagnose no power to the scan tool. Pinpoint Test AE: No Power To The Scan Tool

5. Establish a scan tool session.

- NOTE: The scan tool will first attempt to communicate with the PCM, after establishing communication with the PCM, the scan tool will then attempt to communicate with all other modules on the vehicle.
If an IDS (Integrated Diagnostic System) session cannot be established with the vehicle, (IDS (Integrated Diagnostic System) may state "No communication can be established with the PCM"):

- Choose "NO" when the scan tool prompts whether or not to retry communication.

- Enter either a PCM part number, tear tag or calibration number to identify the vehicle and start a session (the PCM part number and 4-character tear tag are printed on the PCM label).

- GO to Pinpoint Test A, to diagnose The PCM Does Not Respond To The Scan Tool. Pinpoint Test A: The PCM Does Not Respond To The Scan Tool

6. NOTE: During the network test, the scan tool first attempts to communicate with the PCM, after establishing communication with the PCM, the scan tool then attempts 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 7.

- If the network test fails, GO to Symptom Chart to identify the module not communicating. Symptom Related Diagnostic Procedures


7. If the DTCs retrieved are related to the concern, go to DTC Charts. For all other DTCs, refer to the Diagnostic Trouble Code (DTC) Chart in Body Control Systems. Information Bus Body Control Systems/ Body Control Module

8. If no DTCs related to the concern are retrieved, GO to Symptom Chart. Symptom Related Diagnostic Procedures