With Tachometer

Indicators

The operation of an indicator is explained in the operation of its circuit. See the circuit for a complete operation of an indicator and the other components that work with it. Only indicators that do not appear in other schematics are described in this section.

Coolant Temperature Gage

The Coolant Temperature Gage is operated by two coils. Battery voltage is applied to both coils. One is grounded directly and the other is grounded through the Coolant Temperature Sender. This has 55 ohms resistance at 260°F (hot coolant) and its resistance increases at lower temperatures. Resistance is approximately 1400 ohms at 100°F. This causes the current through the sender and H coil to increase as the coolant temperature increases. This moves the pointer.

Fuel Gage

The pointer of the Fuel Gage is moved by the magnetic field of two coils. The coils are at right angles to each other. Battery voltage is applied to the E coil and the circuit divides at the opposite end of this coil. One path continues to ground though the F coil. The other goes to ground through the variable resistor of the Fuel Gage Sender.
When the tank is low, the resistance of the sender is low (0 ohms). A large current passes through the E coil and the Fuel Gage sender resistor. This moves the pointer toward E on the scale. When the tank is full, the sender resistance is high (90 ohms). More voltage is applied through the F coil, moving the pointer toward F on the scale.
With two coils operating the pointer, the gage is not affected by changes in voltage of the system.

Oil Pressure Gage

The engine oil pressure is displayed by the Oil Pressure Gage. The pointer of the gage is moved by two coils, and its operation is similar to that of the Fuel Gage.
The Fuel Pump/Oil Pressure Sender/Switch is connected to the junction of the two coils. It has low resistance when the oil pressure is low, and 90 ohms resistance when oil pressure is high. This changing resistance changes the voltage applied through the coils. The magnetic fields of the coils move the pointer from L to H.

Oil Pressure Indicator

The Pressure Indicator lights to warn the driver when the engine oil pressure is low. Battery voltage is applied to one side of the bulb. A ground path is provided by the Oil Pressure Switch. It is closed when the oil pressure is below 4 psi (27 kPa). This tests the bulb when the Ignition Switch is turned on to start the engine. After the engine starts and normal oil pressure builds up, the Oil Pressure Switch opens. The OIL Pressure Indicator goes off.

Tachometer

The Tachometer displays engine speed in rpm. Voltage pulses are taken from the Ignition System and sent to the Tachometer. Solid state circuits process these pulses into a signal that drives the pointer of the meter. The Tachometer responds to the frequency of the voltage pulses. These pulses increase with engine speed.

Tailgate Ajar Indicator (Wagon only)

With the Ignition Switch in RUN, BULB TEST, or START, voltage is applied through the GAGES Fuse and the TAILGATE AJAR Indicator to the Tailgate Ajar Switch. The indicator receives a path ground when the switch is closed. The switch will be closed with the tailgate unlatched.

Voltmeter

The Voltmeter measures the electrical system voltage with the Ignition Switch in RUN, BULB TEST, or START. With the engine stopped, the Voltmeter indicates battery condition. With the engine running, the Voltmeter indicates Charging System operation.

Speedometer

The Speedometer pointer is moved by the magnetic field of two coils. These coils are driven by a solid state control module.
The Vehicle Speed Sensor, located in the Transaxle, generates a AC voltage that is sent to the Electronic Control Module (ECM). The ECM processes this voltage into a square wave. The pulses generated are sent to the Speedometer at 4000 pulses per mile.

Odometer

The Odometer is a mechanical display. It is driven by an electric stepper motor that is fed from a solid state control module. The stepper motor turns in response to the number of pulses it receives from the ECM.