Solar Sensor: Testing and Inspection

CONTROL SYSTEM INPUT COMPONENTS





Sunload Sensor
The sunload sensor is located on the left defroster grille. It detects sunload entering through the windshield by means of a photo diode and converts it into a current value which is then input to the EATC unit.

Sunload Input Process
The EATC unit includes a processing circuit to "average" variations in detected sunload over a period of time. This prevents drastic swings in the EATC system operation due to small or quick variations in detected sunload.

For example, consider driving along a road bordered by an occasional group of large trees. The sunload detected by the sunload sensor will vary whenever the trees obstruct the sunlight. The processing circuit averages the detected sunload over a period of time. The (insignificant) effect of the trees momentarily obstructing the sunlight does not cause any change in the EATC system operation. On the other hand, shortly after entering a long tunnel, the system will recognize the change in sunload, and the system will react accordingly.














TROUBLE DIAGNOSIS PROCEDURE FOR SUNLOAD SENSOR CIRCUIT

SYMPTOM:
- Sunload sensor circuit is shorted (50 or 52 is indicated on the EATC unit as a result of conducting Self-diagnosis).

ELECTRICAL COMPONENT INSPECTION





Sunload Sensor
After disconnecting sunload sensor harness connector, measure resistance between sensor terminals 1 and 2. The resistance should be greater than 0 ohms depending on the amount of sunlight.

- When checking sunload sensor, select a place where sun shines directly on it.