For 1990-2009 cars

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 be disengaged

• | The DRL control module must not receive a ground signal from the generator (a ground signal from the generator indicates that the engine is not running)

• | The light switch is either in the OFF or PARK position and ambient light sensor senses a bright light condition

When the above conditions are met, a path to ground is provided to the coil of the head relay. Voltage is applied through the closed contacts of the head relay, through the dimmer relay and the head fuses (LH-LWR and RH-LWR) to the low beam lamps in the headlamps. With no ground supplied to the coil of the DRL relay, the headlamps have no direct path to ground. A path to ground is then provided through the DRL control module which reduces the intensity of the headlamps to 80%.

The following will prevent DRL operation:

• | 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 the DRL operation.

• | When the light switch is in the head position, a path to G203 through the light switch is provided to the DRL control module, disabling DRL operation.

• | When the ambient light sensor senses a low light condition for approximately 15 seconds, a path to ground is provided through the DRL relay and SP254 to G103 disabling DRL operation.