Initial Inspection and Diagnostic Overview

INSPECTION AND VERIFICATION

1. Verify the customer's concern by operating the climate control system to duplicate the condition.

Visual Inspection Chart:

2. Inspect to determine if one of the mechanical or electrical concerns apply.
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 an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.

5. NOTE: Make sure to use the latest scan tool software release. If the cause is not visually evident, connect the scan tool to the data link connector (DLC).

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

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.
- refer to Information Bus (Module Communications Network), No Power To The Scan Tool, to diagnose no communication with the scan tool.

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.
- refer to Information Bus (Module Communications Network) to diagnose no response from the powertrain control module (PCM).

8. Carry out the network test:
- If the scan tool responds with no communication from one or more modules, refer to Information Bus (Module Communications Network).
- If the network test passes, retrieve and record the continuous memory diagnostic trouble codes (DTCs).

9. Clear the continuous DTCs and carry out the self-test diagnostics for the PCM.

10. NOTE: Some PCM DTCs may inhibit air conditioning (A/C) operation. If any PCM DTCs are retrieved, diagnose those first. REFER to Computers and Control Systems.

If the DTCs retrieved are related to the concern, go to Computers and Control Systems.

11. If not DTCs related to the concern are retrieved, GO to Symptom Chart. Symptom Related Diagnostic Procedures