DESCRIPTION
Note. LS400 uses a multiplex control system. Check multiplex control system. See MULTIPLEX CONTROL SYSTEM article.
When the headlight switch is in the AUTO position, the system automatically turns on the low-beam headlights (and taillights) if it is dark enough outside. When it is light enough, the system automatically turns the headlights off. If the driver leaves the headlight switch in the AUTO position and turns the ignition off, the headlights will go out when the driver's door is opened. If the headlights come on too early or too late, the system sensitivity can be adjusted. See LIGHT SENSOR ADJUSTMENT .
OPERATION
When intensity of light decreases sufficiently, light sensor internally connects terminals No. 5 and 6. See WIRING DIAGRAMS . This grounds coil circuit of headlight relay (through the headlight switch), causing contacts in headlight relay to close, allowing power to headlights. When the intensity of light increases sufficiently, the light sensor interrupts the internal connection.
When the driver's door is open, the light sensor detects closed contacts in door courtesy switch. Light sensor uses this signal to turn off headlights if headlight switch is in AUTO position when ignition is turned off.
SYSTEM OPERATIONAL TEST
- Turn ignition on. Turn headlight switch to AUTO position. Gradually cover light sensor. Headlights and instrument panel lights should come on. Gradually uncover light sensor. Lights should turn off.
- Gradually cover light sensor. Wait for lights to come on. Lights should turn off under any of the following conditions. Headlight switch is turned to OFF position. Light sensor is exposed. Ignition is turned off and driver's door is opened.
- Turn ignition off. Open driver's door (leave it open). Ensure light sensor is uncovered. Turn ignition on. Lights should turn off.