ON-BOARD DIAGNOSTIC FUNCTION [FULL-AUTO AIR CONDITIONER]

id0702c1100300

Malfunction Detection Function

Fail-safe function

•  If a malfunction is detected by the malfunction detection function and a malfunction is determined, the following controls are performed to prevent an operation malfunction of the full-auto air conditioner and malfunction of output parts.

Fail-safe function table

Part where malfunction is determined	Malfunction determined when IG SW at ON	Malfunction already exists when IG SW turned to ON
Solar radiation sensor	Solar radiation sensor input value is fixed at the value right before the malfunction.	Solar radiation sensor input value is fixed at 0 W/m2.
Cabin temperature sensor	Cabin temperature sensor input value is fixed at the value right before the malfunction.	Cabin temperature sensor input value is fixed at 25 °C {77 °F}.
Ambient temperature sensor	Ambient temperature sensor input value is fixed at the value right before the malfunction.	Ambient temperature sensor input value is fixed at 15°C {59 °F}.
Evaporator temperature sensor	Evaporator temperature sensor input value is fixed at 0 °C {32 °F}.	¨
ECT sensor	ECT sensor input value is fixed at 85 °C {185 °F}.	¨
Air mix actuator (Potentiometer)	•  Air mix actuator drive signal is stopped right after the malfunction is determined. •  However, it is fixed at MAX COLD when the manually set temperature is at 15 (left side of temperature setting dial) and fixed at MAX HOT when the manually set temperature is at 29 (right side of temperature setting dial).	Control based on ambient temperature.
		However, it is fixed at MAX COLD when the manually set temperature is at 15 (left side of temperature setting dial) and fixed at MAX HOT when the manually set temperature is at 29 (right side of temperature setting dial).
Airflow mode actuator (Potentiometer)	•  Airflow mode actuator drive signal is stopped right after the malfunction is determined. •  For manual operation using the mode dial, only vent or defroster mode is operable.	Control based on ambient temperature.
		For manual operation using the mode dial, only vent or defroster mode is operable.
Air mix actuator (Motor lock)	Air mix actuator drive signal is stopped right after the malfunction is determined. After this, a drive signal is output to the air mix actuator and malfunction determination is performed approx. every 5 min.	After the ignition switch is turned to the ON position, the air mix actuator drive signal is output normally again. After this, a drive signal is output to the air mix actuator and malfunction determination is performed approx. every 5 min.
Airflow mode actuator (Motor lock)	Airflow mode actuator drive signal is stopped right after the malfunction is determined. After this, a drive signal is output to the airflow mode actuator and malfunction determination is performed approx. every 5 min.	After the ignition switch is turned to the ON position, the airflow mode actuator drive signal is output normally again. After this, a drive signal is output to the airflow mode actuator and malfunction determination is performed approx. every 5 min.

Sensor signal delay function

•  The ambient and cabin temperatures may change intermittently, partially, or suddenly due to factors such as direct and intermittent sunlight (traveling through a city or a highway tunnel), or radiant heat from the ground under a parked vehicle as well as the opening and closing of doors. If control was performed based exactly on these variations that are input from each sensor, the air conditioning function would be negatively affected and smooth control could not occur. In order to prevent this, the climate control unit delays the input signals for solar radiation, and the ambient and cabin temperature as shown in the following figure. Stable control occurs due to the reading out of an average of all the variations.

•  The ambient temperature sensor may detect a temperature higher than the actual ambient temperature when the engine is restarted after it has been temporarily stopped while the temperature around the engine was high. To prevent this, the ambient temperature is corrected based on the data for the ambient temperature before the engine was stopped which is stored in the climate control unit, and control is then performed accordingly.

am2zzn00000440

Memory function

•  The memory function stores malfunctions in input/output signal systems. With this function, malfunction data is not cleared after the ignition switch is turned off (LOCK position), even if the malfunctioning signal system has returned to normal.

•  To clear stored malfunction data, disconnect the negative battery cable or press the rear window defroster switch and REC/FRESH switch on the climate control unit at the same time while in the past malfunction indication mode.

Display function

•  The display function outputs present or past malfunctions as a DTC to the REC switch indicator light on the climate control unit.

•  A DTC is output when the ignition switch is turned to the ON position with the dial or switch operated as follows.

―  Temperature setting dial: 15 (MAX COLD)

―  Fan dial: Off

―  Mode dial: Defroster

―  Rear window defroster switch and a/c switch are pressed at the same time (hold both switches pressed)

•  DTCs are indicated by the number of flashes of the REC indicator light on the climate control unit.

•  If there is more than one malfunction, DTCs are output in numerical order, from lower to higher numbers.

DTC display example

am2zzn00000726

Present Malfunction Indication Mode

•  Present malfunctions in the control system circuits (open/short circuits) are detected, and the DTCs shown in the table are indicated by the number of flashes of the REC indicator light on the climate control unit.

DTC table

No．	Flashing pattern	System malfunction location	Detection condition	Memory function
02		Solar radiation sensor	Open/short circuit in solar radiation sensor	—
06		Cabin temperature sensor	Open/short circuit in cabin temperature sensor	—
10		Evaporator temperature sensor	Open/short circuit in evaporator temperature sensor	—
12		Ambient temperature sensor	Open/short circuit in ambient temperature sensor	—
14		ECT sensor	Open/short circuit in ECT sensor	—
18		Air mix actuator (potentiometer)	Open/short circuit in air mix actuator (potentiometer)	—
21		Airflow mode actuator (potentiometer)	Open/short circuit in airflow mode actuator (potentiometer)	—

Past Malfunction Indication Mode

•  Past malfunctions in the control system circuits (open/short circuits) are stored, and the DTCs shown in the table are indicated by the number of flashes of the REC indicator light on the climate control unit. Clear past malfunctions after completing repairs since once a past malfunction is stored, it will remain stored even after the malfunction has been repaired.

•  To clear stored malfunction data, disconnect negative battery or press the rear window defroster switch and REC/FRESH switch on the climate control unit at the same time while in the past malfunction indication mode.

DTC table

No．	Flashing pattern	System malfunction location	Detection condition	Memory function
07		Cabin temperature sensor	Detected open/short circuits once or more in cabin temperature sensor	X
11		Evaporator temperature sensor	Detected open/short circuits once or more in evaporator temperature sensor	X
13		Ambient temperature sensor	Detected open/short circuits once or more in ambient temperature sensor	X
15		ECT sensor	Detected open/short circuits once or more in ECT sensor	X
19		Air mix actuator (potentiometer)	Detected open/short circuits once or more in air mix actuator (potentiometer)	X
22		Airflow mode actuator (potentiometer)	Detected open/short circuits once or more in airflow mode actuator (potentiometer)	X
58		Air mix actuator (motor lock)	Detected motor lock once or more in air mix actuator circuit	X
59		Airflow mode actuator (motor lock)	Detected motor lock once or more in airflow mode actuator circuit	X