Gauges

How the Circuit Works

When the ignition is in ON (II) or START (III), battery voltage is supplied through fuse 5 to the gauges in the gauge assembly.

Coolant Temperature Gauge ('97-'99 models)

The coolant temperature gauge is operated by two intersecting coils wound around a permanent magnet rotor. When voltage is applied to the coils, a magnetic field is generated which causes the rotor to rotate and the gauge needle to move. The magnetic fields are controlled by the coolant temperature sending unit. As the resistance in the sending unit varies, current through the gauge coils changes, and the gauge needle moves according to the changing magnetic field.

Coolant Temperature Gauge ('00-'04 models)

The coolant temperature gauge is operated by two intersecting coils wound around a permanent magnet rotor. When voltage is applied to the coils, a magnetic field is generated which causes the rotor to rotate and the gauge needle to move. The magnetic field, controlled by the engine control module (ECM), causes the gauge needle to move toward the coil with the strongest magnetic field.

Engine Oil Pressure Gauge

The engine oil pressure gauge is operated by two intersecting coils wound around a permanent magnet rotor. When voltage is applied to the coils, a magnetic field is generated. The magnetic field causes the rotor to rotate and the gauge needle to move. The magnetic fields are controlled by the engine oil pressure gauge sending unit. As the resistance in the sender varies, current through the gauge coils changes. The gauge needle moves according to the changing magnetic field.

Fuel Gauge

The fuel gauge is operated by two intersecting coils wound around a permanent magnet rotor, and a bucking coil in series with the full coil. When voltage is applied to the coils, a magnetic field is generated which causes the rotor to rotate and the gauge needle to move. The magnetic fields are controlled by the fuel gauge sending unit in the fuel tank. As the resistance in the sending unit varies, current through the gauge coils changes, and the gauge needle moves according to the changing magnetic field. When you turn the ignition switch to LOCK (0), the needle remains at the last reading until you turn it ON again.

Voltmeter

The voltmeter is operated by a resistor and two perpendicular coils in series. When voltage is applied to the gauge, one coil generates a magnetic field that cancels the permanent magnet field which returns the gauge to zero. The field generated by the other coil causes the permanent magnet rotor to rotate and move the gauge needle. The resistor limits current flow through the gauge.

Tachometer

With the ignition in ON (II) or START (III), the tachometer drive circuit in the gauge assembly receives pulses from the engine control module (ECM). The ECM determines the engine speed from the crankshaft position/cylinder position (CKP/CYP) sensor. The number of pulses per minute is directly proportional to the engine speed. The tachometer drive circuit controls the tachometer.

Speedometer and Odometers

With the ignition in ON (II) or START (III), the ODO/trip meter drive circuit and the speedometer drive circuit in the gauge assembly are supplied battery voltage through fuse 5. The ODO/trip meter drive circuit applies 5 volts to the speed input terminal (ORN wire). The vehicle speed sensor (VSS) sends a pulsed signal through the ORN wire by switching its connection to ground on and off. The number of pulses increases as speed increases. The ODO/trip meter drive circuit uses this input to drive the trip and odometer stepper motors, and also supplies it to the speedometer driver to control the speedometer.