Headlamp Control Module: Description and Operation

SYSTEM OUTLINE
With the ignition SW turned on, the current flows to TERMINAL 15 of the body ECU through GAUGE fuse.
Voltage is applied at all times to TERMINAL (A) 11 of the body ECU through the TAIL relay. Coil side, and to TERMINAL (A) 2 through the HEAD relay coil side (w/o daytime running light) or through the daytime running light relay (w/ daytime running light).

1. NORMAL LIGHTING OPERATION

With the light control SW turned to TAIL position, a signal is input into TERMINAL (A) 18 of the body ECU. Due to this signal, the current flowing to TERMINAL (A) 11 of the body ECU flows to TERMINAL (A) 18 to TERMINAL 14 of the light control SW to TERMINAL 16 to GROUND, and taillight relay causes taillights to turn on.

With the light control SW turned to HEAD position, a signal is input into TERMINALS (A) 17 and (A) 18 of the body ECU. Due to this signal, the current flowing to TERMINAL (A) 2 of the body ECU flows to TERMINAL (A) 17 to TERMINAL 13 of the light control SW to TERMINAL 16 to GROUND in the headlight circuit, and causes taillight and HEAD relay to turn the lights on. The taillight circuit is same as above.

2. LIGHT AUTO TURN OFF OPERATION
With light on and ignition SW turned off (Input signal goes to TERMINAL 15 of the body ECU), when the driver's door is opened (Input signal goes to TERMINAL 3 of the body ECU), the ECU operates and the current is cut off which flows from TERMINAL (A) 11 of the body ECU to TERMINAL (A) 18 in taillight circuit and from TERMINAL (A) 2 to TERMINAL (A) 17 in headlight circuit.
As a result, all lights are turned off automatically.