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. Visually inspect for obvious signs of mechanical or electrical damage.
3. As pinpoint tests 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. If the cause is not visually evident, connect the diagnostic tool to the data link connector (DLC) and select the vehicle to be tested from the diagnostic tool menu. If the diagnostic tool does not communicate with the vehicle:
- check that the program card is correctly installed.
- check the connections to the vehicle.
- check the ignition switch position.

6. If the diagnostic tool still does not communicate with the vehicle, refer to the diagnostic tool operating manual.
7. Carry out the DATA LINK DIAGNOSTICS test. If the diagnostic tool responds with:
- CKT 914 or CKT 915 = ALL ECUS NO RESP/NOT EQUIP, refer to Information Bus (Module Communications Network).
- SYSTEM PASSED, retrieve and record continuous diagnostic trouble codes (DTCs), erase the continuous DTCs, and carry out the self-test diagnostics for the EATC module.
- If the electronic automatic temperature control (EATC) module cannot be accessed by the diagnostic tool, GO to Pinpoint Test E. Test E: No Communication With The Electronic Automatic Temperature Control Module

8. If the DTCs retrieved are related to the concern, go to the Powertrain Control Module Diagnostic Trouble Code (DTC) Index or the EATC Module Diagnostic Trouble Code (DTC) Index. Powertrain Control Module (PCM) Diagnostic Trouble Code (DTC) Index Electronic Automatic Temperature Control (EATC) Module Diagnostic Trouble Code (DTC) Index
9. If no DTCs related to the concern are retrieved, GO to Symptom Chart. Symptom Related Diagnostic Procedures

Electronic Automatic Temperature Control Module Self-Test
- The EATC module self-test will not detect concerns associated with data link messages like engine coolant temperature or vehicle speed signals. A diagnostic tool must be used to retrieve these concerns.
- The EATC module self-test will detect concerns in the system control functions and will display hard DTCs in addition to intermittent diagnostic trouble codes for concerns that occur during system operation. The vehicle interior temperature should be between 4°-32°C (40-90°F) when carrying out the self-test. If the temperatures are not within the specified ranges, false in-vehicle temperature sensor DTCs will be displayed.
- The self-test can be initiated at any time. Normal operation of the system stops when the self-test is activated.
- To enter the self-test, press the OFF and FLOOR buttons simultaneously and then press the AUTOMATIC button within 2 seconds. The display will show a pulse tracer going around the center of the display window. The test may run as long as 30 seconds. Record all DTCs displayed.
- If any DTCs appear during the self-test, follow the diagnostics procedure given under ACTION for each DTC given.
- If a condition exists but no DTCs appear during the self-test, GO to Symptom Chart Condition: The EATC System Is Inoperative, Intermittent or Improper Operation. Symptom Related Diagnostic Procedures
- To exit self-test and retain all intermittent DTCs, push the blue (cooler) button. The control will exit self-test, retain all intermittent diagnostic trouble codes and then turn OFF (display blank).
- To exit the self-test and clear all DTCs, press the DEFROST button. The vacuum fluorescent display window will show 888 and all function symbols for one second. Then, the EATC control assembly will turn OFF (display blank) and all DTCs will be cleared.
- Always exit the self-test before powering the system down (system turned OFF).
- Intermittent DTCs will be deleted after 80 ignition switch ON cycles after the intermittent condition occurs.