Instrument Panel, Gauges and Warning Indicators: Description and Operation

Gauges and Indicators

How the Circuit Works

The indicators are controlled by relative conditions in their associated systems. For the following indicators the information supplied to the gauge assembly is received via the multiplex control unit:
- Charging System
- Brake Fluid Level Switch
- Parking Brake Switch
- Maintenance Required Indicator
- Seat Belt Reminder
- Trunk Indicator

Refer to each associated system to see its entire schematic.

Coolant Temperature Gauge

The coolant temperature gauge is controlled by the CPU built-in the gauge assembly. The CPU receives coolant temperature information from the ECM/PCM via the multiplex control unit. The ECM/PCM receives coolant temperature information from the ECT sensor.

Fuel Gauge and Low Fuel Indicator (except GX)

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 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.

Fuel Gauge and Low Fuel Indicator (GX)

WARNING: Compressed natural gas is flammable and highly explosive. You could be killed or seriously injured if leaking gas is ignited. Do not smoke while working on the fuel system. Keep open flame away from the work area. Drain fuel only into an approved sealed container.

The fuel gauge and low fuel indicator are controlled by the CPU built-in the gauge assembly. The CPU receives fuel level information supplied by the PCM. The PCM receives a fuel pressure signal from the fuel pressure regulator switch.

Fuel Gauge and Low Fuel Indicator

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 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 ECM/PCM. The pulse rate increases as the engine speed increases. The frequency and duration of these input pulses are measured by the CPU.