Fog lamp operation is possible with the headlamp and panel dimmer switch in the PARK position or in the HEAD position. However, if the headlamp and panel dimmer switch is in the HEAD position, the fog lamps are only operational if the headlamp dimmer switch is in the LOW position.

With the headlamp and panel dimmer switch in the PARK position or the HEAD position (if the switch is in the HEAD position, the headlamp dimmer switch must be in the LOW position), voltage is available through the closed contacts of the park lamp switch CKT 9 (BRN) to the fog lamp switch. With the fog lamp switch in the ON position, voltage is available through the closed contacts CKT 317 (YEL) of the fog lamp switch to the coil (power side) of the fog lamp relay. Voltage is available to the contact side of the relay through the DRL-FOG fuse 15.

Ground is available from the daytime running lamps (DRL) module to the coil (ground side) of the fog lamp relay, provided that the headlamp dimmer switch is in the LOW position, if the headlamp and panel dimmer switch is in the ON position.

With both power and ground available to the coil of the fog lamp relay, the relay energizes. Then, voltage is available through the closed contacts of the relay to the fog lamp ON indicator, the left fog lamp, and the right fog lamp.

The indicator lamp and the fog lamps light. If the selection of the headlamp dimmer switch changes to the HIGH position when the headlamp and panel dimmer switch is in the HEAD position and the fog lamp switch is in the ON position, then the DRL module receives a high beam headlamp operation signal. Then the DRL module disables the fog lamp relay. This extinguishes the fog lamps.