Park/Marker Lamps

Voltage is applied to the Headlamp Switch at all times. With the Headlamp Switch is in PARK or HEAD, voltage is applied to the Park and Marker Lamps. The front Marker Lamps are grounded through the turn filament of the respective front Park/Turn Lamp. The front Marker Lamps will light as a result.

Oldsmobile and Pontiac are also equipped with automatic lamp control to turn on the Park and Headlamps when the Instrument Panel Cluster, with the use of a Photoresistor, determines that the exterior lamps should be turned on based on available light. When the Instrument Panel Cluster grounds the Park Lamp Relay, voltage is supplied directly to the Park Lamps, bypassing the Turn/Hazard Headlamp Switch. When this occurs, the Automatic Lamp Control Relay is grounded as well, which supplies voltage from the HDLP Circuit Breaker to term A of Conn. C1 of the Turn/Hazard Headlamp Switch Assembly which feeds the Headlamps without requiring that the Turn/Hazard Headlamp Switch be turned on. Once the available light reaches a predetermined level, or if the Ignition Switch is turned to OFF, the Instrument Panel Cluster will no longer supply ground to the Park Lamp Relay or the Automatic Lamp Control Relay, causing the lamps to be turned off.