Fog/Driving Lamp: Description and Operation

CIRCUIT OPERATION
The fog lamp ON indicator is used to indicate to the operator when the fog lamps are ON. Power for the lamp is supplied on circuit L39. This is an output from the for lamp switch.

The fog lamps are controlled by the fog lamp switch located in the headlamp switch, and two fog lamp relays located in the Power Distribution Center (PDC). The fog lamps operate only when the headlamp switch is in the ON position, and the operator has selected LOW beam operation. When the headlamps are in HIGH beam operation, the fog lamps will not operate.

When the headlamp switch is in the ON position and the operator turns the fog lamps ON, circuits F39 and L35 are connected through the fog lamp switch. The F39 circuit is protected by a 20 amp fuse located in cavity 6 of the PDC. Circuit L35 connects from the switch to the fog lamp logic relay located in the PDC.

Circuit L35 connects to the normally CLOSED contact of the logic relay and to circuit L95. The L95 circuit connects to the coil side of the fog lamp ON relay With this input to the ON relay the contacts in the relay CLOSE connecting circuits F39 and L39.

The L39 circuit connects from the relay to the fog lamps. Ground for the fog lamps is supplied on circuit Z1. The L39 circuit is also spliced and provides an input to the message center for fog lamp ON lamp illumination.

If the operator selects HIGH beam operation circuit G34 provides an input to the coil side of the fog lamp logic relay With this input the logic relay switches from its normally CLOSED state to the open state. When the relay switches the battery feed to the fog lamp ON relay is disconnected and the fog lamps are turned OFF.