1972 VW Beetle Instruments Circuit
The fuel gauge is a thermo-electrical indicator located in the speedometer. It indicates the amount of fuel available by a needle moving across a scale. The needle is moved in one direction by a spring and in the other by the heating and bending of a bimetal strip. The bimetal strip is heated by current flow through a coil wrapped around it. Current is provided by a vibrator and controlled by the variable resistor in the fuel gauge sending unit in the tank. The fuel gauge system is protected by a fuse in the fuse box.
Oil Pressure Warning Light
A red oil pressure warning light is also located in the speedometer. It illuminates when the ignition switch is turned on and stays lit until the engine has started and oil pressure is built up. Sufficient pressure displaces a diaphragm in the switch and turns the light off. The light will come on any time the ignition switch is on and the oil pressure drops. The oil pressure light is protected by a fuse in the fuse box.
The horn is a single tone signal. It is operated by the horn button on the steering wheel. Pressing the button sends current to a breaker mechanism within the horn which vibrates a diaphragm to produce sound. The horn system is protected by a fuse in the fuse box. Horn will not blow with the ignition switch off.
The windshield wipers are driven by a single electric motor. Moving the wiper switch lever to the first stop produces a single slow wiping sweep unless the lever is held in position. When the lever is released it centers and the wipers park. When the wiper switch lever is moved to the second position, the wipers continue to sweel slowly until the lever is moved to turn them off. In the third position the wipers sweep rapidly until the lever is moved to turn them off. In each mode the blades park automatically. The wipers will not operate unless the ignition switch is on. The system is protected by a fuse in the fuse box.
Rear Window Defogger (Super Beetle Only)
The rear window defogger is activated by turning the control switch on when the ignition switch is on. This closes a relay and supplies current to the window elements. A warning light in the speedometer comes on simultaneously to remind the driver that the circuit is energized. The rear window defogger system is protected by a fuse in the fuse box and an inline fuse.
Fan Motor (Standard on Super Beetle)
The fresh air fan consists of a two speed unit which blows outside air into the car. Turning the switch to the first stop yields slow motor operation and slight airflow. Turning it to the second increases motor speed and airflow.
Automatic Stick Shift (Super Beetle Only)
The Automatic Stick Shift contains a control valve, selector lever contact, and a starter cut-out switch. Also installed is an automatic transmission fluid temperature circuit. The temperature circuit has an indicator in the speedometer and a control switch which connects the indicator to ground when the fluid is too hot. The indicator is protected by a fuse in the fuse box.
The Automatic Stick Shift circuit has a fuse between the coil and the control valve. With the selector lever and the control valve in any position but neutral, a starter cut-out switch opens the circuit to the starter. This prevents starting the car with the transmission engaged. The circuit is protected by an inline fuse.
Find the complete diagram of 1972 VW Beetle electrical system here.