Instrument Panel, Gauges and Warning Indicators: Description and Operation

How the Circuit Works

The indicator lights are controlled by different conditions in their associated systems. Refer to each associated system to see its entire schematic.

Engine Coolant Temperature Gauge

The engine coolant temperature gauge (part of the LCD Display) is controlled by the CPU in the gauge assembly. The ECT sensor sends a coolant temperature signal to the ECM through the RED/WHT wire (cavity C26). The ECM then sends a coolant temperature signal to the CPU in the gauge assembly through the YEL/GRN wire (cavity C7). The CPU controls the LCD display to turn on the proper segments indicating the coolant temperature.


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 (part of the LCD display) and the low fuel indicator light are controlled by the CPU in the gauge assembly. The fuel gauge sending unit (part of the fuel tank unit) sends a fuel level signal to the CPU in the gauge assembly through the YEL/BLK wire (cavity C8). The signal varies depending on the position of the float in the fuel tank which changes the resistance of the sending unit. The sending unit's resistance varies as given:

The CPU controls the LCD display to turn on the proper segments indicating the fuel level. When the fuel level drops below the LOW level, the CPU grounds the low fuel indicator light, which turns the light on.

Speedometer and Odometer

The speedometer and odometer (part of the LCD display) are controlled by the CPU in the gauge assembly. The CPU receives a pulsing input from the vehicle speed sensor. The pulse rate increases as the car accelerates. The frequency and duration of these input pulses are measured by the CPU. The CPU controls the LCD display to turn on the proper segments indicating the vehicles speed and mileage.

Tachometer

The tachometer (part of the LCD display) is controlled by the CPU in the gauge assembly. The CPU receives a pulsing input from the ECM. The frequency and duration of these input pulses are measured by the CPU. The CPU controls the LCD display to turn on the proper segments indicating the engine speed.