Gauges and Indicator

The indicators are controlled by relative conditions in their associated systems
Refer to each associated system to see its entire schematic.

Coolant Temperature Gauge ('99-'00)
The coolant temperature gauge has two intersecting coils wound around a permanent magnet rotor. Voltage applied to the coils, through fuse 9 (in driver's under-dash fuse/relay), generates a magnetic field. The magnetic field, controlled by the coolant temperature sending unit, causes the rotor to rotate and the gauge needle to move. As the resistance in the sending unit varies, current through the gauge coils changes, moving the gauge needle toward the coil with the strongest magnetic field.

The coolant temperature sending unit's resistance varies from about 137 ohms at low engine coolant temperature to between 30-46 ohms at high temperature (radiator fan running).

Coolant Temperature Gauge ('01 -'03)
The coolant temperature gauge is controlled by the CPU built-in the gauge assembly. The CPU receives coolant temperature information from the PCM. The PCM receives coolant temperature information from the ECT sensor.

Fuel Gauge and Low Fuel Indicator Light

WARNING: Do not smoke while working on the fuel system. Keep open flame away from the work area. Drain fuel only into an approved container.

The fuel gauge and low fuel indicator are controlled by the CPU built-in the gauge assembly. The CPU receives fuel level information from the fuel gauge sending unit.

The fuel gauge sending unit's resistance varies from about 11-13 ohms at full to about 130-132 ohms at empty. The fuel level signals current changes with the varying resistance, which enables the CPU to determine the level of the fuel. When the CPU determines that the fuel level is low, it turns the low fuel indicator on. When you turn the ignition switch to LOCK (0), the gauge returns to the bottom of the gauge dial regardless of the fuel level.

Speedometer and Odometer
The odometer circuit drive and the speedometer are controlled by the CPU built-in the gauge assembly. The CPU receives pulses from the PCM. The pulse rate increases as the car accelerates. The frequency and duration of these input pulses are measured by the CPU.

Tachometer
The tachometer is controlled by the CPU built-in the gauge assembly. The CPU receives pulses from PCM. The pulse rate increases as the engine speed increases. The frequency and duration of these input pulses are measured by the CPU.