ON-BOARD DIAGNOSTIC FUNCTION OUTLINE [HVAC]
id0702a2100100
• Based on the sunlight intensity and temperature signals from the various sensors, the climate control unit performs very complex control to the output actuation devices. Therefore, the operating condition of the output devices may vary due to input conditions, even though the controls on the climate control unit are not changed. As a result, when a malfunction occurs in the control system, it may be difficult to reproduce the symptom and to isolate the malfunctioning part of the system. To avoid such difficulty, the climate control unit is programmed with a on-board diagnostic function which input system is malfunctioning. It can also check the output system separately from the input system.
• The on-board diagnostic function has three modes: present failure indication, past failure indication, and output device operation check.
• The climate control unit terminal 1F is connected to the body ground by the body grounding of the A/C check connector, whereby voltage fluctuation occurs. The climate control unit detects this voltage fluctuation and activates the on-board diagnostic function.