Electronic Instrument Cluster
Quick Checks
Use the instrument cluster system schematics, descriptions and Quick Checks for an isolated view of each system for troubleshooting purposes. The description provides an understanding of how the system works and the Quick Check tells what should happen during operation.
Voltage and resistance measurements may be obtained using Rotunda Digital Volt-Ohmmeter 014-00407 or equivalent.
Fuel Gauge
Description
The instrument cluster looks for resistance values at sender to be in the range of 10 ohms to 172 ohms.
Quick Check
Be certain of fuel level.
Fuel gauge does not display rapid change in fuel level if vehicle was driven after turning on ignition switch lock cylinder. Stop vehicle. Turn ignition switch lock cylinder to OFF position, wait 34 seconds, then turn ignition switch lock cylinder to the RUN position.
Diagnostic bars (top two and bottom two bars lighted) indicate that fuel sender circuit is out-of-range. Also the digital displays either CO or CS. This means:
CO: Circuit open or resistance higher than 178 ohms.
CS: Circuit short or resistance less than 7 ohms.
Fuel Gauge Schematic
Dimmer Circuit
Description
When the headlamps are turned on, dimming voltage is supplied to Connector B, Pin 13 and Connector A, Pin 7. Dimming voltage varies between 5 volts and battery voltage depending on the rheostat position. The feed to Connector B is used to dim the VF (vacuum fluorescent) displays. The feed to Connector 7 provides power to the transmission range indicator bulb only.
Quick Check
Verify that the fuse is OK.
Check to see that all dimmable functions dim properly.
Check for proper voltages at instrument cluster.
Dimmer Schematic
Tachometer Circuit
Description
The tachometer signal feed to the instrument cluster is accomplished through Circuit 11 (DG-4). The signal is supplied to the cluster through Connector B, Pin 20. The instrument cluster interprets the signal and displays RPM.
Quick Check
Verify signal to instrument cluster.
Service Circuit 11 or replace instrument cluster as required.
Tachometer Schematic
Charging System
Description
Connected between Connector A, Pins 17 and 18 is the charge warning indicator and 422-ohm resistor (internal to the instrument cluster). When a charging system concern occurs, Circuit 904 is grounded through the generator regulator (10316) regulator and the warning indicator illuminates. The charge system warning is located next to the temperature gauge.
If Connector A is disconnected, the vehicle will not produce a charge. The 422-ohm resistor allows the charging system to operate.
Quick Check
Look for a charging system warning that normally occurs with ignition switch lock cylinder in RUN position, engine off. The warning should come on within approximately 15 to 20 seconds.
Start engine and charging system warning should go away. Wait at least 15 seconds.
Charging System Schematic
Coolant Temperature Sender
Description
Coolant temperature sender resistance varies depending on coolant temperature.
The instrument cluster interprets the resistance and displays the temperature in the
instrument cluster
Quick Check
Sensor resistance should be between 1400 and 12,000 ohms with engine at normal operating temperature.
Verify continuity in Circuit 39.
Engine Coolant Temperature Sensor Schematic
Instrument Cluster
Quick Check
1. Depress E/M and SELECT simultaneously while turning the ignition switch lock cylinder from OFF to the RUN position. The instrument cluster will enter special test mode and display information in the center display opening. Information displayed includes a number in the speedometer and two numbers in the odometer. The tachometer bar will also be illuminated. Both the left and right display openings will be off.
2. If any of the information in the center opening flashes on and off continuously, the instrument cluster is damaged and should be replaced. If the display does not flash, turn ignition switch lock cylinder off to leave the special test mode. Continue through the diagnosis section (the instrument cluster may or may not be malfunctioning at this point).
Instrument Cluster
