With Standard Cluster

The operation of an individual indicator is described along with its circuit. Refer to the schematic and text for the circuit that is stated below or above wires leading to that indicator.

Stop Engine Oil Indicator

Voltage is applied through the STOP ENGINE OIL Indicator to the Engine Oil Pressure Switch. The Engine Oil Pressure Switch is open with normal oil pressure. With low engine oil pressure, the switch closes and the indicator grounds through the switch.

Speedometer and Odometers

The standard swing needle speedometer is quartz electrically controlled.

The Speedometer circuit consists of Driver and Logic IC (integrated Circuit) chips, a crystal oscillator, and some discrete electrical components. These components - diodes, resistors, and capacitors-act as buffers, power surge suppressors and EMI (electro-magnetic interference) protection by limiting and filtering the various input and output signals.

The Vehicle Speed Sensor (VSS) is a permanent magnet generator mounted in the trans- axle designed to replace the Speedometer drive gear and sleeve. The purpose of the VSS is to provide an AC (alternating current) speed signal that is proportional to the vehicle speed at a rate of 4000 pulses per mile. This AC signal is transmitted filtered and conditioned, then transmitted to the Speedometer circuitry. The Buffer sends amplified electrical pulses to the quartz mechanism in the Speedometer, which converts it to a mechanical movement.

The Odometers are driven by a Stepper Motor that is controlled by the same electrical pulses that are sent by the Vehicle Speed Sensor Buffer.

The Speedometer graphics illustrate mph at the top of the numerical scale and km/h (kilo- meters per hour) at the bottom. The odometers measure distance in miles.

Display Illumination

The Body Computer Module (BCM) supplies 16 volts to the vacuum fluorescent displays for illumination, and signal to dim the displays. When the Headlights are off, the vacuum fluorescent displays are at maximum intensity. When the Headlights are on, the driver can adjust the intensity of the vacuum fluorescent displays by rotating the head- light knob. The Headlight knob controls the lighting rheostat which sends a variable voltage to the BCM. The BCM produces a dimming signal based on the voltage from the lighting rheostat.

Fuel Data Center

The Fuel Data Center (FDC) uses vacuum fluorescent displays to show fuel level and fuel related information. The Body Computer Module (BCM) provides the FDC with necessary voltages and data communication. All information for display is sent to the FDC from the BCM through the PPL wire. A clock signal, used to synchronize Input and Output data, is sent over the YEL wire. Five volt computer power is sent over the TAN wire. Sixteen volt vacuum fluorescent display power is sent over the ORN/BLK wire. A dimming voltage for the vacuum fluorescent display is sent over the GRY/WHT wire.

When the Ignition Switch is set to RUN, current from Fuse 7 flows to the FDC and a 3 second display segment check is made, after which operating data is displayed.

Fuel Gage Sender

With the Ignition Switch in RUN, BULB TEST, or START, voltage is available through Fuse 16 to the Fuel Gage Sender, which is a potentiometer in the Fuel Tank Unit. The moving arm of the potentiometer provides an input voltage to the Body Computer Module (BCM) determined by the amount of fuel in the tank. If the tank is full, the voltage is at maximum as supplied by the Battery. If the tank is empty, the voltage will be near zero or ground. The variable voltage from the Fuel Gage Sender is sent to the BCM and converted for display by the Fuel Data Center.

Information Centers

The wiring schematic of the Information Center shows seven different Indicators. Circuit details showing how the Indicators turn on are shown on the schematic of each respective circuit, except for SERVICE AIR COND Indicator. This circuit is described below.

Voltage is applied to the SERVICE AIR COND Indicator with the Ignition Switch in RUN, BULB TEST, or START. The Refrigerant Low Side Temperature Sensor senses the temperature of the refrigerant in the system low pressure side. The sensor sends this signal to the Body Computer Module. If the refrigerant charge has been depleted, system cooling will decrease. The Body Computer Module will detect this condition through the Refrigerant Low Side Temperature Sensor and will provide ground for the SERVICE AIR COND Indicator. The Indicator operates to warn the driver of the low refrigerant charge.