Symptom Related Diagnostic Procedures

COMPONENT DESCRIPTION
The sunload sensor is located on the right defroster grille. It detects sunload entering through windshield by means of a photo diode. The sensor converts the sunload into a current value which is then input to the auto amplifier.
Measure Voltage between auto amp. terminal (10) and body ground.

SUNLOAD INPUT PROCESS
The auto amp. also includes a processing circuit which "average" the variations in detected sunload over a period of time. This prevents drastic swings in the ATC system operation due to small or quick variations in detected sun load.
For example, consider driving along a road bordered by an occasional group of large trees. The sunload detected by the sun load sensor will vary whenever the trees obstruct the sunlight. The processing circuit averages the detected sunload over a period of time, so that the (insignificant) effect of the trees momentarily obstructing the sunlight does not cause any change in the ATC 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.





DIAGNOSTIC PROCEDURE
SYMPTOM: Sunload sensor circuit is open or shorted. (25 or -25 is indicated on auto amp. as a result of conducting Self-diagnosis STEP 2.)








COMPONENT INSPECTION

SUNLOAD SENSOR
When checking sun load sensor, select a place where sun shines directly on it.