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Initial Inspection and Diagnostic Overview

INSPECTION AND VERIFICATION

1. Verify the customer 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 and measurements are being performed, 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 a diagnostic tool to the data link connector 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:
- SCP+, SCP-, or UBP CIRCUITS FAULT = ALL ECUS NO RESP/NOT EQUIP, refer to Information Bus (Module Communications Network) to diagnose the network concern.
- If the powertrain control module (PCM) is not listed for a communication concern, turn the A/C controls to OFF and execute the self-test diagnostics for the PCM.
- If the EATC module is not listed for a communication concern, execute self-test diagnostics for the EATC module.

8. If any PCM or EATC DTCs are retrieved, and are related to the concern, go to the Powertrain Control Module Diagnostic Trouble Code (DTC) Index or the Electronic Automatic Temperature Control (EATC) Module Diagnostic Trouble Code (DTC) Index to continue diagnostics. 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 to continue diagnostics. Symptom Related Diagnostic Procedures
10. If the 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

Electronic Automatic Temperature Control Module - Diagnostic Methods
The electronic automatic temperature control system must be diagnosed by first retrieving any DTCs, if present.
- An on-demand (hard fault) DTC indicates that the fault is currently present. An on-demand DTC suggests a wiring fault, disconnected connector, or component failure.
- A continuous (intermittent) DTC alone (corresponding on-demand DTC is not present) indicates that the fault is an intermittent condition and may not be currently present. A continuous only DTC suggests a poor wiring connection, loose pin or terminal, or intermittent component failure.

On-demand (hard fault) or continuous (intermittent fault) DTCs can be retrieved using a diagnostic tool. If using a diagnostic tool, refer to the diagnostic tool operating manual.

On-demand DTCs can also be retrieved by carrying out the Electronic Automatic Temperature Control Module Self-Test. To retrieve and/or clear continuous DTCs carry out the Electronic Automatic Temperature Control Module - Retrieve Continuous DTCs procedure. Always carry out the Electronic Automatic Temperature Control Module Self-Test before retrieving continuous DTCs.

If no DTCs are present, GO to Symptom Chart for the appropriate diagnostic action. 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 diagnostic trouble codes (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 performing the self-test. If the temperatures are not within the specified ranges, false in-car 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 two 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 temperature) button. The control will exit self-test, retain all intermittent DTCs and then turn OFF (display blank).
- To exit 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.

Electronic Automatic Temperature Control Module - Retrieve Continuous DTCs
The EATC module will retrieve only continuous (intermittent) DTCs when carrying out this procedure.
- Retrieval of continuous DTCs can be initiated after cycling the ignition switch from OFF to ON. Normal operation of the climate control system stops when retrieving continuous DTCs.
- To retrieve continuous DTCs press the OFF and PANEL buttons simultaneously and release, then press the AUTO button within two seconds. All vacuum fluorescent segments will be displayed if there are no continuous DTCs present. Continuous DTCs are indicated by the presence of the degrees Celsius symbol (�C) on the EATC module display. Record all DTCs displayed.
- If any DTCs appear, carry out the diagnostic procedure. Refer to the Electronic Automatic Temperature Control Module Diagnostic Trouble Code Index and follow the ACTION for each DTC given. Electronic Automatic Temperature Control (EATC) Module Diagnostic Trouble Code (DTC) Index
- If a condition exists but no DTCs appear, GO to Symptom Chart Condition: The EATC System Is Inoperative, Intermittent or Incorrect Operation. Symptom Related Diagnostic Procedures
- To exit and retain all continuous DTCs, press any button except DEFROST. The EATC module will exit the retrieve continuous DTCs mode and retain all continuous DTCs.
- To exit and clear all continuous DTCs, press the DEFROST button. The EATC module will exit the retrieve continuous DTCs mode and all continuous DTCs will be cleared.
- Always exit the procedure before powering the system down (system turned OFF). Once the procedure is exited the ignition switch must remain ON for at least 30 seconds to allow the temperature blend door actuators to automatically recalibrate.
- Continuous DTCs will be deleted after 80 ignition switch ON cycles after the intermittent fault occurs.
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