Headlamp: Description and Operation

Current from the battery is always flowing from the FL Main --> ST MAIN fuse --> Headlight Relay (Coil Side) --> TERMINAL 5 of the Daytime Running Light Relay (Main) and TERMINAL 14 of the Dimmer SW [Comb. SW], headlight relay (Coil Side) --> TERMINAL 3 of the Integration Relay --> TERMINAL 4 --> TERMINAL 13 of the light control SW [Comb. SW), FL Main --> ST MAIN fuse -->Daytime Running Light Relay no.2 (Coil Side) TERMINAL 17 of the Daytime Running Light Relay.

1. DAYTIME RUNNING LIGHT OPERATION
When the engine is started, voltage generated at TERMINAL 'L' of the Generator (Alternator) is applied to TERMINAL 11 of the Daytime Running Light Relay (Main).

If the parking brake lever is pulled up (parking brake SW ON) at this time, the relay is not energized, so the daytime running light system does not operate. If the parking brake lever is released (parking brake lever SW OFF), the signal is input to TERMINAL 8 of the relay. This activates the relay and current from ST MAIN flows to Daytime Running Light Relay no.2 (Point Side) HEAD HI (LH) fuse --> TERMINAL 1 of the headlight HI LH TERMINAL 2 --> TERMINAL 2 of the Headlight HI RH --> TERMINAL 1 --> TERMINAL 4 of the Daytime Running Light Relay no.3 --> TERMINAL 2 --> 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 come ON, the headlights remain ON even if the parking brake lever is pulled up (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 (Alternator), 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 lever 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 [Comb. SW] at the HEAD position
When the light control SW [Comb. SW] is set to HEAD position, the current flowing to the Headlight Relay (Coil Side) flows to TERMINAL 3 of the Integration Relay --> TERMINAL 4 --> TERMINAL 13 of the light control SW [Comb. SW] --> TERMINAL 11 --> GROUND, turning the Headlight Relay ON.

This causes the current flowing to the Headlight Relay (Point Side) --> DRL fuse --> Daytime Running Light Relay no.3 (Coil Side) and Daytime Running Light Relay no.4 (Coil Side) --> GROUND, turning the Daytime Running Light Relay no.3 and no.4 ON. Also, current from the Headlight Relay (Point Side) to HEAD (LWR) fuses --> TERMINAL 1 of the headlights LO --> TERMINAL 2 --> GROUND, so the headlights (LO side) light up.

* Dimmer SW [Comb. SW] at FLASH position
When the Dimmer SW [Comb. SW] is set to FLASH position, current flows from Headlight Relay (Coil Side) --> TERMINAL 14 of the Dimmer SW [Comb. SW] --> TERMINAL 9 --> GROUND, turning the headlight relay ON. At the same time, signals are output from TERMINAL 12 and TERMINAL 14 of the Dimmer SW [Comb. SW] to TERMINAL 16 and TERMINAL 5 of the Daytime Running Light Relay (Main), activating the Daytime Running Light Relay (Main) and also the Daytime Running Light Relay no.2. When the Headlight Relay (Main) and Daytime Running Light Relay (Main) are activated, the headlights (LO and HI) then light up.

* Dimmer SW [Comb. SW] at HIGH position
When the light control SW [Comb. SW] is set to HEAD position, a signal is output from TERMINAL 13 of the Light Control SW (Comb. SW) --> TERMINAL 4 of the Integration Relay --> TERMINAL 3 --> TERMINAL 5 of the Daytime Running Light Relay (Main). When the Dimmer SW [Comb. SW] is set to HIGH position, a signal is output from TERMINAL 12 of the Dimmer SW [Comb. SW] to TERMINAL 16 of the Daytime Running Light Relay (Main). These signals activate Daytime Running Light Relay no.2, so current flows from Daytime Running Light Relay no.2 (Point Side) HEAD HI (LH) fuse --> TERMINAL 1 of the Headlight HI LH --> TERMINAL 2 --> Daytime Running Light Relay no.4 (Point Side) --> GROUND, and current also simultaneously flows from HEAD HI (RH) fuse --> Daytime Running Light Relay no.3 (Point Side) --> TERMINAL 1 of the Headlight HI RH --> TERMINAL 2 --> Daytime Running Light Relay no.4 (Point Side), causing the headlights (HI side) to light up.