Theory Of Operation

When the ignition is on, the Body Control Module (BCM) provides a 12 volt signal on the Left and Right Front Lamp Fault Sense circuit to the Front Lamp Assemblies and to the Left and Right Stop Lamp Fault Sense circuit to the Tail Lamp Assemblies. When the Left or Right Turn Lamp is activated, an internal driver in the Lamp Assemblies will pull the Fault Sense circuit voltage signal low (below 6 volts), in sequence with the Turn Lamp flash. When the Turn Lamps are Off, the BCM will maintain the Fault Sense circuit high (above 8 volts).

A failure in the Fault Sense circuit may be caused by one of the following:

• When the Turn Lamps are activated, and the voltage on the Fault Sense circuit is approximately 12 volts at all times, may indicate an open Fault Sense circuit, poor connection or inoperative Lamp Assembly.
• When the Turn Lamps are Off, the Lamp Assembly is not disconnected, and the voltage on the Fault Sense circuit is below 6 volts, may indicate a shorted Fault Sense circuit, a shorted Lamp Assembly or water/corrosion at a harness connector/terminal.
• When the Lamp Assembly is disconnected, the Fault Sense circuit is not shorted, and the voltage on the Fault Sense circuit is below 6 volts, may indicate the BCM is not supplying the 12 volt signal on the Fault Sense circuit.