Headlight Doors

CIRCUIT OPERATION:
Battery voltage to open and close the Headlight Doors is applied to terminal B of the Headlight Door Module connector C1. The module is grounded at terminal D of connector C1 through the 150 circuit to 0100.

OPENING SEQUENCE:
When the Light Switch is in HEAD or Twilight Sentinel is activated, battery voltage is applied to both terminals A and C of the Headlight Door Module connector C1. With battery voltage applied to both terminals A and C, the Headlight Door Module does not energize its relay. Voltage is applied to terminal B at the Headlight Doors Motor. The motor is controlled by the module switching the ground path. When the doors are fully open the module turns "OFF" the motor.

NOTE: Measuring voltage at the motor outputs of the Headlight Door Module is NOT a valid diagnosis procedure. The module rapidly pulses the door motor "ON" (hi) and "OFF" (low). The pulsing is too rapid to see or measure with a voltmeter. When the pulse signal is low the spinning door motor acts like a generator. The module can detect the voltage produced by the motor and continues the pulsing signal. The door motor stops turning when the headlight doors are fully open, fully closed or jammed. Once the motor stalls, no voltage is produced and the module turns off the motor. If the motor runs longer than approximately 6 seconds (disconnected drive linkage) the module will turn off the motor.

CLOSING SEQUENCE:
When the Light Switch is pressed "OFF" or Twilight Sentinel is de-activated, battery voltage is removed from terminals A and C of connector C1 at the Headlight Door Module. The module allows the doors to close when it sees a ground, through the Lo Beam Headlight filaments, at terminal C of connector C1. The module energizes its relay and battery voltage is applied to terminal A of the Headlight Doors Motor. The motor is controlled by the module switching the ground path. When the doors are fully closed the module turns "OFF" the motor.

NOTE: Measuring voltage at the motor outputs of the Headlight Door Module is NOT a valid diagnosis procedure. See Opening Sequence for additional information.