Headlamp: Description and Operation

Current from the battery is always flowing from the FL main --> MAIN fuse --> head relay (coil side) --> TERMINAL 2 of the daytime running light relay (main) and TERMINAL 8 of the dimmer SW, head relay (coil side) --> TERMINAL B-3 of the integration relay --> TERMINAL B-4 --> TERMINAL 13 of the light control SW, FL main --> MAIN fuse --> DRL no.2 relay (coil side) --> TERMINAL 9 of the daytime running light relay (main).

1. DAYTIME RUNNING LIGHT OPERATION
When the engine is started, voltage generated at TERMINAL 'L' of the generator is applied to TERMINAL 5 of the daytime running light relay (main).

If the parking brake pedal is depressed (parking brake SW ON) at this time, the relay is not energized. So the daytime running light system does not operate. If the parking pedal lever is released (parking brake SW OFF), the signal is input to TERMINAL 4 of the relay. This activates the relay and current from MAIN fuse flows to DRL no.2 relay (point side) --> HEAD (LH) fuse --> TERMINAL 1 of the headlight LH (LH) --> TERMINAL 2 --> TERMINAL 2 of the headlight RH (HI) --> TERMINAL 1 --> TERMINAL 3 of the DRL no.3 relay --> TERMINAL 4 --> 4 to GROUND, causing the headlights to light up dimmer than normal brightness.

This is how the daytime running light system operates once the daytime running light system operates and the headlights have light up, the headlights remain ON even if the parking brake pedal is depressed (parking brake SW ON).

Even if the engine stalls with the ignition SW ON and there is no voltage from TERMINAL 'L' of the generator. The headlights remain ON, if the ignition SW is then turned OFF, headlights are turned OFF.

If the engine is started while the parking brake pedal is released (parking brake SW OFF), the daytime running light system operates and the headlights light up as the engine starts.

2. HEADLIGHT OPERATION
* When the light control SW at the HEAD position
When the light control SW is set to HEAD position, the current flowing to the head relay (coil side) flows to TERMINAL B-3 of the integration relay --> TERMINAL B-4 --> TERMINAL 13 of the light control SW --> TERMINAL 16 --> GROUND, turning the head relay ON.

This causes the current flowing to the head relay (point side) --> DRL no.2 fuse --> DRL no.3 relay (coil side) and DRL no.4 relay (coil side) --> GROUND, turning the DRL no.3 and no.4 relay ON. Also, current from the head relay (point side) to HEAD (LWR) fuses --> TERMINAL 2 of the headlights (LO) --> TERMINAL 3 --> GROUND, so the headlights (LO side) light up.

* Dimmer SW at FLASH position
When the dimmer SW is set to FLASH position, current flows from head relay (coil side) --> TERMINAL 8 of the dimmer SW --> TERMINAL 16 --> GROUND, turning the head relay ON. At the same time, signals are output from TERMINAL 7 and TERMINAL 8 of the dimmer SW to TERMINAL 8 and TERMINAL 2 of the daytime running light relay (main), activating the daytime running light relay (main) and also the DRL no.2 relay. When the head relay and daytime running light relay (main) are activated, the headlights (LO and HI) then light up.

* Dimmer SW at HIGH position
When the light control SW is set to HEAD position, a signal is output from TERMINAL 13 of the light control SW --> TERMINAL B-4 of the integration relay --> TERMINAL B-3 --> TERMINAL 2 of the daytime running light relay (main). When the dimmer SW is set to HIGH position, a signal is output from TERMINAL 7 of the dimmer SW to TERMINAL 8 of the daytime running light relay (main). These signals activate DRL no.2 relay, so current flows from DRL no.2 relay (point side) --> HEAD (LH) fuse --> TERMINAL 1 of the headlight LH (HI) --> TERMINAL 2 --> DRL no.4 relay (point side) --> GROUND, and current also simultaneously flows from HEAD (RH) fuse --> DRL no.3 relay (point side) --> TERMINAL 1 of the headlight RH (HI) --> TERMINAL 2 --> DRL no.4 relay (point side), causing the headlights (HI side) to light up.