With Daytime Running Lights (DRL)

CIRCUIT OPERATION



The Daytime Running Lights (DRL) Module is designed to automatically turn on certain lights depending on outside light conditions. The DRL Module operates in two modes, the day mode and the night mode. In the day mode the Front Turn Lights are lit. In the night mode the Headlights, and Front Marker and Tail Lights are turned on.

When the DRL Module is in the day mode the Left and Right DRL Relays are energized, allowing voltage to be applied to the LH and RH Front Turn Lights through the DRL Relay's contacts. If the driver operates the Turn Signal Switch to signal a turn, the DRL Module will sense battery voltage being applied at either the right or left turn signal input. The DRL Module will then de-energize the appropriate DRL Relay, allowing the turn signal to flash.


When the Photoresistor senses darkness the DRL Module's Headlights Relay and Park Relay are energized, allowing voltage to be applied to the Headlights and Exterior Lights. If the engine should stall when the DRL Module is in the night mode, the DRL Module will turn off the Headlights and leave the Marker, Park and Tail Lights on while the engine is being cranked.


Photoresistor

The Photoresistor is a light sensitive variable resistor. Its resistance decreases as outside light intensity increases. The DRL Module measures the voltage drop across the Photoresistor and determines whether the DRL Module should operate in the day mode or the night modes.

Parking Brake Input

If the Parking Brake is applied before the Ignition Switch is turned to RUN, the DRL Module will not turn on any lights. This allows the operator to start the car and keep all lights off as long as the Parking Brake remains applied. Once the lights come on they will stay on. To turn them off the Ignition must be turned off to reset the feature. This feature is intended for use during service or while parked at a drive-in theater, etc. If the Light Switch is in the PARK or HEAD position, the parking brake will have no effect on the Headlights and Exterior Lights operation.


Headlights On Signal

When the Headlights are turned on using the Light Switch the DRL Module will sense battery voltage being applied at the Headlights on signal (C1/F) and the DRL system will be overridden. If the DRL Module is in the day mode the LH and RH Front Turn Lights will be turned off by the DRL Module.