Indicators Cluster

The operation of an individual indicator is described along with its circuit. Refer to the schematic and text for the circuit described below.

Fuel Gage

The magnetic fields of two coils, which are at right angles to each other, move the pointer of the Fuel Gage. Battery voltage is applied to the E coil, and the circuit divides at the opposite end of the coil. One circuit goes to ground through the F coil. Another goes to ground through the variable resistor of the Fuel Gage Sender.
When the tank is low, the resistance of the Sender is low. A larger current passes through the E coil and the Fuel Gage Sender resistor to move the pointer towards E on the scale. When the tank is full, the Sender resistance is high. More current now flows through the F coil, which moves the pointer towards F on the scale.

Coolant Temperature Gage

Two coils also operate the Coolant Temperature Gage. Battery voltage is applied to both coils. One is grounded directly and the other is ground through the Coolant Temperature Sender. The Coolant Temperature Sender has 55 ohms resistance at 127°C (260°F) and its resistance becomes greater at lower temperatures. It has approximately 1400 ohms at 38°C (100°F). This varying resistance causes the current through the Sender and one coil to charge as the coolant temperature increases. This moves the pointer.

Speedometer and Odometer

The Speedometer is operated by an electronic circuit. The Vehicle Speed Sensor (VSS), located in the Transaxle, generates an AC voltage with a frequency proportional to the speed of the vehicle. This goes to the Powertrain Control Module (PCM) and then to the Speedometer circuit board in the Instrument Cluster. This Solid State unit drives the pointer of the Speedometer.
The same buffered speed signal from the Powertrain Control Module (PCM) is processed to drive the Odometers. The Odometers are operated by a stepper motor that responds to pulses from the Speedometer circuit.

Coolant Temperature Indicator

The Coolant Temperature Indicator lights to warn of overheating when the Coolant Temperature Sender/Switch is closed. The Powertrain Control Module (PCM) controls this Indicator. When the PCM senses an over-temperature condition, it grounds the Coolant Temperature Indicator. When the Ignition Switch is in RUN with the engine off, the Coolant Temperature Indicator is grounded by the PCM as a bulb test.

CHECK OIL Indicator

The CHECK OIL Indicator lights to alert the driver of a low engine oil level condition. The low oil sensing circuit consists of a Low Oil Level Sensor and an Oil Level Module. This system is active only at initial engine starting and not while the engine is running.
The oil level will be measured if the engine has been off long enough for top engine oil to have returned to the pan and if the vehicle is on a fairly level surface. The Oil Level Module receives battery power at all times to retain memory of engine on and off times.
When the Ignition Switch is turned to RUN, battery voltage is applied to the ignition on input of the Oil Level Module, and the Oil Level Module grounds the CHECK OIL Indicator for 2 seconds as a bulb check. If the ignition ON input has been at 0 volts for at least 8 minutes and the internal attitude sensor indicates that the vehicle is resting on a surface with an incline of 20 degrees or less, the Oil Level Module activates the Low Oil Level Sensor. If the sensor returns a signal indicating a good oil level signal, the indicator will remain off. If the sensor returns a signal indicating a low oil condition, the indicator is lit 15 to 20 seconds after the bulb check. If the Ignition Switch is turned off for less than 20 seconds, the Oil Level Module will remember and display the previous oil level status and ignore the present oil status. If the ignition has been off for more than 20 seconds, but less than 8 minutes, the Oil Level Module will ignore the Low Oil Level Sensor and perform a bulb check only.

Oil Pressure Indicator

The Oil Pressure Indicator goes on to warn of low oil pressure when the Oil Pressure Switch is closed. The Oil Pressure Switch closes when the oil pressure falls below 27 kPa (4 psi). When the engine is initially cranked, oil pressure is below 27 kPa (4 psi), so the Oil Pressure Switch closes, and the Oil Pressure Indicator goes on momentarily as a bulb test. The Oil Pressure Switch opens as soon as the oil pressure is above 27 kPa (4 psi), and the Oil Pressure indicator goes off.