The daytime running lamps (DRL) control module is designed to automatically operate the exterior lights depending on the outside light conditions.

The DRL control module operates in the following 2 modes:

The DRL control module operates in the night mode whenever the DRL ambient light sensor detects darkness. The night mode contacts close, applying voltage to the headlamps and other exterior lamps through the same circuit path as when the headlamp switch is in the HEAD position.

If the engine should stall with the DRL control module in the night mode, the DRL control module deactivates the headlamps, leaving the marker, park and tail lamps activated while the engine is being cranked. The headlamp switch operates as usual.

The DRL ambient light sensor is a light sensitive variable resistor. The DRL ambient light sensor's resistance decreases as the outside light intensity increases. The DRL control module measures the voltage drop across the DRL ambient light sensor determining whether it should operate in the day mode or in the night mode.

The DRL control module will not operate any headlamps or exterior lamps if the park brake is applied before the ignition switch is turned to the RUN position. This allows the operator to start the vehicle and keep the headlamps OFF, as long as the park brake is applied. The DRL control module will activate the headlamps when the park brake is released with the ignition switch in the RUN position.

This feature will only function when the park brake is applied before the ignition switch is turned to the RUN position. The headlamps will not turn off if the park brake is applied after the ignition switch is turned to the RUN position.

Voltage is applied continuously to the PARK fuse to the headlamp and the instrument panel (IP) lamp dimmer switch through CKT 1340.

When the headlamp and the (IP) lamp dimmer switch is in the PARK or HEAD position, voltage is applied to CKT 9 thus activating the following lamps:

The park/turn lamps are the only lamps that do not activate yet receive a current from CKT 9. The park/turn lamps do not activate because the voltage drop across the front side marker lamps is much higher than that across the turn lamp filaments.

When the ignition switch is the in the following positions:

Voltage is applied through the T/SIG fuse through CKT 539 to the normally closed pole of the turn switch in the turn signal switch assembly, then to the hazard lamp/turn signal flasher through CKT 1508 then back to the turn signal switch through CKT 16.

Voltage is applied from the turn signal switch through CKT 1414 to the DRL control module and then through CKT 14 to the turn filaments of the left front park/turn lamps, when the turn signal switch is the LEFT TURN position. Voltage is also applied through CKT 18 to the left rear turn lamp, the left front side marker and the left turn indicator. The lamps flash ON and OFF as current flow heats up the timing element in the hazard lamp/turn signal flasher, causing it to continuously open and close the circuit. The RIGHT TURN position works in a similar way through CKT 1415 and CKT 19 to the right turn lamps.

Voltage is applied to both terminals of the front side marker lamps causing them to be OFF, when the park lamps and the turn lamps activate. When the turn lamps are not operating, voltage is applied to only 1 terminal of the side marker lamp causing it to flash. The side marker and the turn lamps continue to flash ON and OFF, until the turn switch is turned OFF.

Voltage is applied continuously through the HAZARD fuse through CKT 1840 to the normally open poles of the hazard switch in the turn signal switch assembly.

Voltage is applied to the hazard lamp/turn signal flasher through CKT 1508 then back to the turn signal switch through CKT 16, activating the following lamps to flash ON and OFF:

Voltage is applied continuously through the STOP LAMP fuse to the stop lamp switch through CKT 140. Depressing the brake pedal applies voltage through the stop lamp switch to CKT 17, thus activating the left and the right stop lamp filaments in the tail/stop lamps and in the center high mounted stop lamp (CHMSL).