Per Joe:
Front Panel DATC Module Self-Test (On-demand Diagnostic Trouble Codes—DTCs)
On-demand DTCs are those that are reported by an ECU when a failure is detected while executing a diagnostic test. For the DATC module this means that all faults (hard) that occur while the module is conducting a self-test shall be reported as an on-demand DTC.
* The DATC module self-test will not detect concerns associated with data link messages such as engine coolant temperature or vehicle speed signals. The scan tool must be used to retrieve these concerns.
* The vehicle interior temperature should be between 0-32°C (32-90°F) when carrying out the self-test. If the temperatures are not within the specified ranges, false temperature sensor DTCs may be displayed.
The DATC module self-test through the front panel display:
* can be initiated at any time. Normal operation of the system stops when the self-test is activated.
* is entered by pressing the OFF and FLOOR buttons simultaneously and then pressing the AUTO button within two seconds. The display will show counts of 1 to 25 in the center of the display window. Record all DTCs displayed.
* concludes by reporting all on-demand DTCs. Follow the diagnostics procedure given under ACTION in the DTC index for each DTC given.
* reports individual on-demand DTCs as four-digit DTCs (less the alpha character).
* will calibrate all the mode doors and check all analog inputs. The DATC module will only report on-demand (hard) faults that occurred while the DATC module was conducting its self-test.
* will light all control panel display segments if no faults are detected.
* will report individual on-demand DTCs without the °C symbol lit.
To exit the self-test, press any button. This will clear all on-demand codes from the DATC module memory. If no button is pushed DTCs will continue to be displayed.
Upon exit from the self-test the DATC module returns to operational status. The DATC module executes a hard (cold boot) reset which places the DATC system in the OFF mode.
If a condition exists but no DTCs appear during the self-test, GO to Symptom Chart Condition: The DATC System Is Inoperative, Intermittent or Incorrect Operation.
Always exit the self-test before powering the system down (system turned OFF).
Front Panel DATC Module Display—Retrieve Continuous Diagnostic Trouble Codes (DTCs)
Continuous DTCs are fault codes recorded by the DATC module which have occurred during normal operation. For the DATC module this means that all faults (intermittent or hard) that occur while the module is in an operational state shall be reported as a continuous DTC.
* To retrieve continuous DTCs, press the OFF and PANEL buttons simultaneously, followed by pressing the AUTO button within two seconds.
* The DATC module will report all continuous DTCs to the vacuum fluorescent (VF) display.
* The DATC module will not carry out a self-test; it will only display continuous faults codes which are stored in memory.
* All VF display segments will light if no faults are detected.
* Individual continuous DTCs will be reported with the °C symbol lit.
* DTCs shall be reported as a four-digit DTC (less the alpha character).
* Pressing the front defrost button will exit the retrieve continuous DTCs mode and clear all continuous DTCs from DATC module memory.
* Pressing any other button (other than DEFROST) will exit the retrieve continuous DTCs mode and maintain all continuous DTCs in DATC module memory.
* Upon exit from the retrieve continuous DTCs mode the DATC module returns to operational status. The DATC module executes a hard (cold boot) reset which places the DATC system in the OFF mode.
Mechanical failure of the DCCV is not detected by the diagnostics, only electrical problems. Mechanical failure of the AC clutch, or low R-134 levels are also not detected.
