Trip Computer: Description and Operation

CIRCUIT DESCRIPTION

GAUGES Operation
With the ignition switch in ON or START, battery voltage is applied to the gauges (Speedometer, Tachometer, Fuel Gauge and Engine Coolant Temperature Gauge) from Fuse 2.

Speedometer
The speedometer drive circuits receive pulses from the Vehicle Speed Sensor (VSS). The pulse rates increase as the car accelerates. The frequency and duration of these input pulses are measured and displayed by the speedometer.

Tachometer
The tachometer displays engine speed in rpm. Voltage pulses are taken from the ignition system and sent to the tachometer. The tachometer responds to the frequency of the voltage pulses which vary according to engine speed. The PCM processes theses pulses into a signal that causes the gauge needle to move.

Fuel Gauge
The pointer of the fuel gauge is moved by the magnetic field of two coils. The coils are at right angles to each other. The magnetic field, controlled by the fuel gauge sender, causes the gauge needle to move. As the resistance in the sender varies, current through the gauge coils changes.

Engine Coolant Temperature Gauge
The pointer of the engine coolant temperature gauge is moved by the magnetic field of two coils. The coils are at right angles to each other. The magnetic field, controlled by the engine coolant temperature sender, cause the gauge needle to move. As the resistance in the sender varies, current through the gauge coils changes.

Trip system
The Trip computer in the instrument cluster displays all kinds of information related to driving such as average speed drive time and drive able distance on the LCD display. The trip computer receives input signals through the PCM, the fuel sender and so on.
According to the input signals, the trip computer sends output signals (trip information) to the LCD display.

INDICATOR Operation
With the ignition switch in ON or START, battery voltage is applied to the indicator bulb from Fuse 2.

Oil pressure indicator
When the oil pressure is low (oil pressure switch is closed), ground is provided to the oil pressure indicator bulb. The oil pressure does not register when the engine is not running or with ignition ON. In that case, the pressure switch remains closed and the indicator illuminates.

Check ENGINE indicator
The ground of the indicator is controlled by the PCM. The control module will light the indicator when the engine is not running or when it detects engine problems.