Tachometer: Description and Operation

Fuel Gauge
The fuel gauge contains two intersecting coils and a permanent magnet rotor assembly which displays the fuel level even with the ignition switch in the LOCK (0) position. The fuel gauge sensor controls the magnetic field which varies the current to the fuel gauge and causes the gauge pointer to move. The fuel gauge indicates a full tank when the sender resistance is 3.5 to 5 ohms. The fuel gauge indicates a half tank when the sender resistance is 29.5 to 35.5 ohms. The fuel gauge indicates an empty tank when the sender resistance is 105 to 108 ohms.

The gauge assembly receives battery voltage at all times through fuse 56 and through fuse 20 with the ignition switch in ON (II) or START (III). The gauge assembly also receives battery voltage through fuse 55 and the gauge relay with the ignition switch in ON(II) or START (III).

Engine Coolant Temperature Gauge
The engine coolant temperature gauge contains two intersecting coils and a permanent magnet rotor assembly which displays the coolant temperature even with the ignition switch in the LOCK (0) position. The coolant temperature sending unit controls the magnetic field which varies the current to the coolant temperature gauge and causes the gauge pointer to move. The coolant temperature gauge indicates hot, 855°C (1855°F) to 1005°C (2125°F), when the sender resistance is 46 to 30 ohms. The gauge indicates cold, 565°C (1335°F), when the sender resistance is 137 ohms.

Speedometer and Odometer
The speedometer and odometer drive circuits receive pulses from the vehicle speed sensor (VSS). The pulse rate increases as the vehicle speed increases. This speed signal is converted and displayed by the speedometer, odometer and trip meter.

Tachometer
The tachometer drive circuit receives pulses at the rate of three pulses per engine revolution from the powertrain control module (PCM). The pulse frequency increases as the engine speed increases. This speed signal is converted and displayed by the tachometer.

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.

Outside Air Temperature Gauge
The outside air temperature display receives temperature information from the outside air temperature sensor through the BRN/WHT wire. The gauge assembly converts this signal into a digital display. The climate control system also uses this sensor.