Circuit Operation

HEADLAMPS OPERATION
The headlamps are controlled by the Daytime Running Lamps (DRL) Control Module and the Light Switch/Dimmer Switch. When the Light Switch is turned to HEAD and the Dimmer Switch is in LOW, ground is provided to the Headlamp Relay coil through Junction Connector 2, Light Switch, Junction Connector 3 and Junction Connector 1 to G200. Since battery voltage is applied at all times to the Headlamp Relay coil, it becomes energized. Voltage is then applied through the closed contacts of the Headlamp Relay and the Head Fuses (LH-LWR and RH-LWR) to the Low Beam Lamps in the Headlamps. Since ground is provided at all times to G104, the Low Beam Lamps light.

With the Dimmer Switch in HIGH, ground is provided to the DRL Control Module through the Light Switch, Junction Connector 3 and Junction Connector 1 to G200. Since voltage is applied at all times through ECU-B Fuse to the DRL Control Module and grounded at all times through Junction Connector 3 and Junction Connector 1 to G200, the DRL Control Module provides a ground to the coil of DRL Relay 2. Since voltage is applied at all times to the - DRL Relay 2 coil, it becomes energized. Voltage is then applied through the closed contacts of DRL Relay 2 and the Head Fuses (LH-UPR and RH-UPR) to the High Beam Lamps in the Headlamps. Voltage is applied to the coils of DRL Relay 3/4 through the DRL Fuse and the closed contacts of the Headlamp Relay, as described in the previous paragraph. The coils of DRL Relay 3/4 are grounded at all times through Junction Block 1 to G104. With voltage and ground provided to the coils of DRL Relay 3/4, they become energized. Since ground is provided to the High Beam Lamps through the closed contacts of the energized DRL Relay 3/4 and Junction Block 1 to G104, the High Beam Lamps light.

The operation of the Headlamps with the Dimmer Switch in PASS is similar to the operation of the Dimmer Switch in the HIGH position, as mentioned in the previous paragraph, with the exception that 2 ground paths are provided to the DRL Control Module. One path is through Junction Connector 2, Dimmer Switch and Junction Connector 1 to G200, which also provides a path to ground for the Headlamp Relay coil. This simulates the operation of the Light Switch in the HEAD position. The other is through the Dimmer Switch and Junction Connector 1 to G200.

DRL OPERATION
With the Ignition Switch in "ON" or "START," voltage is applied to the DRL Control Module through the GAUGE Fuse. A number of conditions must be met before the Daytime Running Lamps system will work properly: the parking brake must he disengaged, the DRL Control Module must not receive a ground signal from the Generator (a ground signal from the generator indicates that the generator is not charging the battery) and the Light Switch is either in the "OFF" or PARK position. When the parking brake is engaged, the Parking Brake Switch closes, providing a ground to the DRL Control Module, disabling DRL operation. This only happens when the car is first started: after disengaging the Parking Brake the first time, the DRL operation will continue even if the Parking Brake is re-engaged. When the Generator is not running, a switch in the Generator closes, providing a ground to the DRL Control Module, disabling DRL operation. When the Light Switch is in the HEAD position, a path to G200 through the Light Switch is provided to the DRL Control Module, disabling DRL operation.

When all these conditions are met, a path to ground is provided to the coil of DRL Relay 2. Voltage is applied through the closed contacts of DRL Relay 2 and the Head Fuse (LH-UPR) to the High Beam Lamp in the LH Headlamp. With no voltage applied to DRL Relay 3/4, the High Beam Lamp in the LH Headlamp has no direct path to ground. Since ground is provided at all times to the High Beam Lamp in the RH Headlamp and the High Beam Lamps are spliced together, the LH and RH High Beam Lamps are connected in series. With voltage applied to the High Beam Lamp in the LH Headlamp, and ground provided to the High Beam Lamp in the RH Headlamp through Junction Connector 2, the un-energized contacts of DRL Relay 3 (in DRL Relay 3/4 assembly) and Junction Block 1 to G104, the High Beam Lamps will light at half intensity.

The DRL Control Module will also provide a ground to the DRL Indicator when the DRL operation conditions are met. With voltage applied to the DRL Indicator through the GAUGE Fuse, and ground provided through the DRL Control Module, Junction Connector 3 and Junction Connector 1 to G200, the DRL Indicator will light.