Principles of Operation

The SJB  monitors the headlamp switch position by sending a voltage reference signal to the headlamp switch. When the fog lamp switch (part of the headlamp switch) is engaged, the voltage reference signal is routed to ground.

The fog lamps can be turned on when the following conditions are met:

• The ignition switch is in the RUN or START position.
• The low beam headlamps or the parking lamps are on.
• The high beams are off.

When the SJB  receives an input from the headlamp switch indicating a request for the fog lamps, the SJB  energizes the fog lamp relay (internal to the SJB  ). When the fog lamp relay is energized, voltage is routed to the fog lamps and the fog lamps on indicator (located within the headlamp switch).