Instrument Panel, Gauges and Warning Indicators: Description and Operation
Instrument Cluster:
The electronic cluster consists of a vacuum fluorescent display that is made up of digital and/or alpha numeric characters formed from separate anode segments. The vacuum fluorescent displays are controlled by the microprocessor in the electronic instrument module. The major difference between the electronic instrument cluster and the conventional cluster is the way information is displayed. The electronic cluster uses the same senders as the conventional cluster. The speedometer can display in either miles per hour (mph) or kilometers (Km/H) each time the E/M switch on the instrument cluster is depressed. The electronic instrument cluster consists of an electronic speedometer, electronic fuel gauge, and warning lamps.
ELECTRONIC SPEEDOMETER
The speedometer cable for the electronic cluster is identical to the cable used on conventional speedometers. The cable drives a slotted encoder wheel. An optical sensor in the odometer assembly detects rotation of the encoder wheel slots. The optical sensor generates an electrical pulse for each slot. The electrical pulse is used by the speedometer electronics to determine vehicle speed.
ELECTRONIC FUEL GAUGE
The electronic fuel gauge system consists of an electronic fuel gauge module with a vacuum fluorescent bar graph display and a modified fuel sender. The display is divided into four groups. There are eight small bars in the bottom group, indicating 1/32 tank divisions. There are four larger bars in each of the upper three groups, indicating 1/16 tank divisions. The fuel level is indicated by the number of lighted bars. The fuel gauge has a self contained voltage regulator. The Low Fuel Warning System within the electronic fuel gauge has two warning features:
^ The low fuel warning lamp in the diagnostic warning light center above the instrument panel will glow when the fuel gauge indicator is approximately 1/8 tank (bottom four segments illuminated).
^ The ISO (International Standards Organization) symbol on the fuel gauge will start to flash when the fuel gauge indicator is approximately 1/8 tank.
DISPLAY RESPONSE MODES
The fuel gauge has two display response modes. After the prove out has been completed, the fuel gauge is in the normal response mode. In this mode the fuel sender signal is damped to reduce the tendency for the display to fluctuate due to fuel slosh in the tank. It is normal for the gauge to drop a bar after rapid starts and stops or after severe cornering conditions. After parking on steep inclines, the fuel sender signal may cause the gauge to read too high or to low when the vehicle is started. The gauge will begin to correct itself within three to six minutes after returning to level road conditions.
The second display response mode is for fuel tank filling conditions. This mode is entered when the fuel gauge determines that the display is six small bars or three large bars too low (3/16 tank). When this condition occurs, the gauge will begin updating the display in four to eight second intervals. It may take the gauge up to two minutes to determine the condition before it switches to the faster update mode. When the displayed level is the same as the fuel sender level for four seconds, the gauge will switch back to the normal damped response mode.
PROVE OUT
Electronic Speedometer Prove Out Sequence:
Fuel Gauge Prove Out Sequence:
When the ignition switch is turned to the RUN or ACC position, the speedometer and fuel gauge will initiate a four second prove out sequence which will allow verification of the display segments.