The goal of this article is to provide information regarding the rotating headlight circuit of the First Generation Charger (1966-1967) and assist the owners of these vehicles in restoring and maintaining the function of the rotating headlights.
Relay: A relay is an electromechanical device which allows a low-current switch to control a high current switch. A relay has an electromagnetic coil which can open and close a mechanical switch when the coil is energized and de-energized.
Normally Open: this is a switch or relay whose contacts are open in it's normal, or passive, state. The OPEN and CLOSE relays are normally open, as is the Headlight switch.
Normally Closed: this is a switch or relay whose contacts are closed in it's normal, or passive, state. The CONTROL relay is normally closed, as are the Hold Open and Limit switches.
Alright, this is the start of the good stuff.
The OPEN circuit is the less complex circuit, so we will cover that first.
When the headlight switch is closed (turned on), it allows current to pass to the Light Green circuit. This circuit feeds the headlights and the Open and Control relays. The Light Green circuit energizes the Control Relay coil, which opens the contacts and turns off power to the Close Relay coil, shutting down the Close circuit. The Light Green circuit also provides power to the Indicator Light. Finally, and most important, the Light Green circuit energizes the coil of the Open relay which closes the Open Relay contacts. The Open relay contacts energize the Violet circuit, which energizes the Open windings in the Motors and makes the Motors turn in the Open direction. The headlights keep turning until they hit the Upper Limit Switches. When BOTH of Upper Limit Switches are opened by the Motors, the ground path is taken away from the Open Relay, de-energizing the Open Relay coil. This causes the Open Relay contacts to open, and shuts off the Motors. . The switches also shut off the ground for the indicator light, turning off the light.
When the Headlight switch is open (turned off), this de-energizes the coil of the Control Relay, which allows the contacts to close. The Control Relay contacts energize the coil of the Close Relay IF the Hold Open switch is closed. If the Hold Open switch is open, then there is no path to ground for the Close Relay, the Close Relay coil cannot energize, and the Close circuit is disabled.
When the coil of the Close Relay is energized, this closes the Close Relay contacts, which energizes the Red/Orange circuit. The Red/Orange circuit energizes the Close windings in the Motors, causing the Motors to turn in the close direction. When BOTH of Lower Limit Switches are opened by the Motors, the ground path is taken away from the Close Relay, de-energizing the Close Relay coil. This causes the Close Relay contacts to open, and shuts off the Motors.