Auto-On Headlight Sensor On-Vehicle Inspection

Disconnect negative (-) cable at battery.
Remove auto-on headlight sensor (1) located on the passenger side of the dashboard (3). Be careful not to damage the sensor (1) and dashboard by using rag (2).

Fig 1: Identifying Auto-On Headlight Sensor, Rag And Dashboard
Courtesy of SUZUKI OF AMERICA CORP.
Measure voltage between white wire terminal and black wire terminal at the following condition.
If measured voltage is out of specification, replace sensor.

Auto-on headlight sensor voltage specifications

Cover the sensor lens with hand: 0.4 V

Light the sensor lens with incandescent lamp 100 W: 3 - 4.5 V

Fig 2: Measuring Voltage Between Black And White Wire Terminals
Courtesy of SUZUKI OF AMERICA CORP.