Initial Inspection and Diagnostic Overview

Inspection and Verification
1. Verify the customer's concern by operating the climate control system to duplicate the condition.
2. Inspect to determine if one of the following mechanical or electrical concerns apply:

Visual Inspection Chart:

3. As pinpoint tests and measurements are being carried out, be sure to inspect for any disconnected, loose-fitting or incorrectly installed component, module and in-line electrical connectors and pins.
4. If the inspection reveals obvious concerns that can be readily identified, repair as necessary.
5. If the cause is not visually evident, connect the scan tool to the data link connector (DLC).

NOTE: Make sure to use the latest scan tool software release.

6. If the scan tool does not communicate with the VCM:
- check the VCM connection to the vehicle.
- check the scan tool connection to the VCM.
- see PINPOINT TEST 14: NO POWER TO THE SCAN TOOL, Pinpoint Test 14: No Power to the Scan Tool to diagnose no communication with the scan tool.

NOTE: The vehicle communication module (VCM) LED prove-out confirms power and ground from the DLC are provided to the VCM.

7. If the scan tool does not communicate with the vehicle:
- verify the ignition key is in the ON position.
- verify the scan tool operation with a known good vehicle.
- see PINPOINT TEST 15: THE ELECTRONIC MANUAL TEMPERATURE CONTROL (EMTC) MODULE DOES NOT RESPOND TO THE SCAN TOOL, Pinpoint Test 15: The Electronic Manual Temperature Control (Emtc) Module Does Not Respond to the Scan Tool to diagnose no response from the EMTC module.

8. Carry out the network test.
- If the scan tool responds with no communication from one or more modules, see COMMUNICATIONS NETWORK - TROUBLESHOOTING.
- If the network test passes, retrieve and record the continuous memory DTCs.

9. Clear the continuous DTCs and carry out the self-test diagnostics from the PCM, and the EMTC module.
10. If the EMTC module DTCs retrieved are related to the concern, go to the EMTC Module DTC Chart. EMTC Module DTC Chart If the PCM DTCs retrieved are related to the concern, see DIAGNOSTIC TROUBLE CODE (DTC) INDEX - POWERTRAIN CONTROL MODULE (PCM). For all other DTCs, see DIAGNOSTIC TROUBLE CODE (DTC) CHART - B, C AND U CODES. Engine Control System
11. If no DTCs related to the concern are retrieved, see SYMPTOM TROUBLESHOOTING CHART - CLIMATE CONTROL. Symptom Related Diagnostic Procedures