On-Board Diagnostic Function
Outline- The on-board diagnostic function in the A/C amplifier locates and indicates malfunctions in the control system.
- The on-board diagnostic function has three steps.
Present diagnostic test mode ....................Electrical faults presently occuring in the control system are detected and indicated as diagnostic trouble codes.
Past diagnostic test mode ........................Electrical faults that previously occurred in the control system (intermittent problems) are detected and indicated as diagnostic trouble codes.
Output device operation check mode ..........All output devices are made to operate individually according to a designated pattern.
- The on-board diagnostic function works as shown. To turn off the on-board diagnostic function, turn off the ignition switch.
Operation Flow
Condition Detection Mode Using NGS
1. Warm up the engine.
2. Turn the ignition switch to LOCK.
3. Connect the SST(NGS) to the date link connector and battery.
4. Set the SST(Super MECS Adapter) to AUX 1.
5. Select "VEHICLE & ENGINE SELECTION" on the SST(Control Unit) display, and then select the vehicle model, engine type, and model year.
6. Select "DIAGNOSTIC DATA LINK" on the SST(Control Unit) display.
7. Select "A/C-AIR CONDITIONER MODULE" on the SST(Control Unit) display.
8. Select "DIAGNOSTIC TEST MODE" on the SST(Control Unit) display.
9. Start the on-board diagnostic function as indicated on the SST(Control Unit) display.
NOTE:
- if the solar radiation sensor is not lit, a failure will be indicated.
10. Start present diagnostic test mode, past diagnostic test mode, or output device operation check mode.
11. If past failures are indicated, carry out "Erasing past failure memory" after correcting all failed systems.
Present diagnostic test mode
- Immediately after starting the on-board diagnostic function, present failures in the control circuit, such as disconnections or short circuits, are detected and indicated on the SST(Control Unit) as diagnostic trouble codes. If a diagnostic trouble code is indicated, refer to the following diagnostic trouble code table and inspect the appropriate system. (The SST(Control Unit) will not, however, detect a short circuit in the (W) solar radiation sensor signal wire.)
Past diagnostic test mode
- When the A/C switch is pressed with the system in present diagnostic test mode, the A/C amplifier changes the on-board diagnostic function to past diagnostic test mode. In this mode, any past failures, such as disconnections or short circuits, detected and memorized by the A/C amplifier are indicated on the SST(Control Unit) as diagnostic trouble codes. If a diagnostic trouble code is indicated, refer to the following diagnostic trouble code table and inspect the appropriate system. (Disconnections and short circuits are memorized even if they occur only once.) If the A/C switch is pressed again while in past diagnostic test mode, the on-board diagnostic function will return to present diagnostic test mode.
NOTE:
- Only when"(Past)" appears on the display, the A/C amplifier is in the past diagnostic test mode, otherwise the A/C amplifier is in the present diagnostic test mode.
Diagnostic trouble code table
Erasing past failure memory
- Past failures are memorized and remain in the memory even after the failed systems are corrected. The next time the system is serviced, the past failure diagnostic trouble codes will appear again on the SST(Control Unit), even though there is actually no failure. Therefore, erase past failure memory after correcting all failed systems. To erase past failure memory, press the AUTO and REC/FRESH switches on the heater control unit at the same time while in past diagnostic test mode. Past failure memory will be erased and "1" will be indicated on the SST(Control Unit).
Output device operation check mode
- When the AUTO switch is pressed with the system in present diagnostic test mode, the A/C amplifier changes to output device operation check mode. In this mode, all output devices, indicator lights, and the information display operate individually according to a designated pattern, as shown. Each step is charged by pressing the REC/FRESH switch. When the AUTO switch is pressed again, the on-board diagnostic function will return to present diagnostic test mode.
Output device operation check table