Lamp Out Indicator: Description and Operation

CAUTION: Use of additional lights, external trailer lights or improper relacement bulbs may result in false warning or no warning.

When the Rear Park Lamps are turned on, the Lamp Out Warning Module senses for a burned out Rear Park Lamp filament. If a lamp-out condition is detected, the Warning Module illuminates the TAIL LAMP OUT Indicator in the Message Center.

When the Lo Beam Headlamps are turned on, the Lamp Out Warning Module senses for a burned out Lo Beam Headlamp filament. If a lamp-out condition is detected, the Warning Module illuminates the HEADLAMP OUT Indicator in the Message Center.

When a turn signal or a hazard signal is activated, or when the brakes are applied, the Lamp Out Warning Module senses for a burned out Stop/Turn Lamp filament. If a lamp-out condition is detected, the Lamp Out Warning Module illuminates the BRAKE LAMP OUT Indicator in the Message Center.

To detect a lamp-out condition, the vehicle incorporates a special body wiring harness containing several resistive wires. These resistive wires are used to feed the lamps being sensed, and their shunt voltages provide the inputs to the Lamp Out Warning Module. When the bulbs are operating correctly, the voltage drop across the resistive wires will provide approximately .5 volts to the Module. Note that the Module has been designed to sense one or two bulb systems only. In a two bulb system where only one bulb is operating, the input voltage will be approximately .25 volts. If both bulbs are out, the input voltage is 0. In a one bulb system, the input voltage is at approximately .5 volts if the bulb is operating. It is 0 volts if the bulb is not operating. These voltage differences are sensed by the Module and the outputs are set accordingly.

NOTE: Headlamps and tail lamps are two bulb systems; each Rear Brake Lamp is a one bulb system.