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Home >> Ford >> 1998 >> Mustang V6-3.8L VIN 4 >> Repair and Diagnosis >> Instrument Panel, Gauges and Warning Indicators >> Instrument Cluster / Carrier >> Description and Operation >> Instrument Cluster

Instrument Cluster





The instrument cluster contains the following:
^ electric speedometer/tachometer assembly
^ fuel gauge/engine coolant temperature gauge assembly
^ oil pressure/voltmeter gauge assembly

Warning indicators are provided as follows:
^ Safety belt
^ AIR BAG
^ CHECK ENGINE
^ O/D OFF
^ THEFT
^ BRAKE
^ ANTI-LOCK
^ High beam
^ Left turn signal
^ Right turn signal
^ Charging system warning
^ LOW COOLANT

Printed Circuit
The instrument cluster printed circuit which supplies current to the instrument panel lamps and gauges, is made of copper foil which is bonded to a polyester base film (usually referred to as Mylar).

Fuel Level Indicating System
The fuel level indicating system is a magnetic-type indicating system, consisting of:
^ The fuel pump module located in the fuel tank.
^ An instrument cluster gauge amplifier located in the back of the instrument cluster.
^ NOTE: The fuel gauge, engine coolant temperature gauge, and instrument cluster gauge amplifier are calibrated together and must be replaced as a single unit.
^ A fuel gauge located in the instrument cluster. The pointer of the magnetic gauge remains in position when the ignition switch is turned to OFF position.

Fuel Gauge

CAUTION: Do not remove magnetic gauge pointers; the gauge cannot be recalibrated.

NOTE: An instrument voltage regulator is not required for this system.

The fuel gauge, engine coolant temperature gauge, and instrument cluster gauge amplifier are calibrated together and must be replaced as a single unit.

The fuel gauge has the following features:
^ Four primary coils, two of which are wound at a 90 degree angle to the other two.
^ The coils form a magnetic field which varies in direction according to the variable voltage of the instrument cluster gauge amplifier.
^ The instrument cluster gauge amplifier converts the fuel pump module variable resistance to voltage.
^ A rotor magnet, to which a shaft and pointer are attached, rotates to align to this primary field, resulting in pointer position.
^ The bobbin/coil assembly is pressed into a metal housing which has two holes for dial mounting.
^ There is no adjustment, calibration or maintenance required for this gauge.






The Instrument Cluster Gauge Amplifier:
^ provides a delay to fuel gauge to prevent the fuel gauge pointer from fluctuating as a result of excessive movement in the fuel tank.
^ is a small printed circuit board which snaps into a pocket on the back of the instrument cluster.
^ The electrical connections for ignition, ground, input from fuel pump module and output to fuel gauge are made through a spring-type connector on the instrument cluster gauge amplifier to the instrument cluster printed circuit on the instrument cluster.

NOTE: The fuel gauge, engine coolant temperature gauge, and instrument cluster gauge amplifier are calibrated together and must be replaced as a single unit.

Fuel Level Sensor
^ The fuel pump module consists of a variable resistor controlled by the level of an attached float in the fuel tank. This fuel level sensor portion of the fuel pump module performs the following:
^ When the fuel level is low, resistance in the fuel level sensor is low and movement of the gauge indicator pointer is minimal (from EMPTY position).
^ When the fuel level is high, the resistance in the fuel level sensor is high and gauge indicator pointer movement is greater (further from the EMPTY position).

Coolant Temperature Indicating System
The engine coolant temperature indication system is a magnetic-type indication system consisting of:
^ The water temperature indicator sender unit located in the engine block or cylinder head
^ An engine coolant temperature gauge in the instrument cluster

The water temperature indicator sender unit changes resistance according to engine coolant temperature (ECT), which varies the current flow through the engine coolant temperature gauge. The pointer position varies proportionally to the current flow. The engine coolant temperature gauge resistance is high when the engine coolant temperature is low, and low when the engine coolant temperature is high.

NOTE: The fuel gauge, engine coolant temperature gauge, and instrument cluster gauge amplifier are calibrated together and must be replaced as a single unit.

The pointer of the magnetic engine coolant temperature gauge remains in position when ignition switch is turned OFF. It will move to the correct indication whenever the ignition switch is turned back to RUN position.

The gauge pointer may indicate at the top of the normal band with the engine coolant temperature within specification, under certain driving conditions such as heavy traffic or stop-and-go driving in hot weather.

Coolant Temperature Gauge

CAUTION: Do not remove magnetic gauge pointers; the engine coolant temperature gauge cannot be recalibrated.

NOTE: An instrument voltage regulator is not required for this system.

^ The magnetic engine coolant temperature gauge movement consists of three primary coils, one of which is wound at a 90 degree angle to the other two.
^ The coils form a magnetic field which varies in direction according to the variable resistance of the water temperature indicator sender unit.
^ A primary magnet, to which a shaft and pointer are attached, rotates to align to this primary field, resulting in pointer position.
^ The bobbin/coil assembly is pressed into a metal housing which has two holes for dial mounting.
^ There is no adjustment, calibration or maintenance required for this engine coolant temperature gauge.

Water Temperature Indicator Sender Unit
The water temperature indicator sender unit is installed on the engine into an engine coolant passage. The water temperature indicator sender unit reacts to the engine coolant temperature. Its resistance decreases as the engine coolant temperature increases.

Oil Pressure Indication System
The oil pressure indication system consists of an oil pressure switch and a magnetic oil pressure gauge in the instrument cluster.

Oil Pressure Gauge

CAUTION: Do not remove magnetic gauge pointer. Gauge cannot be recalibrated.

NOTE: An instrument voltage regulator is not required for this system.

^ The magnetic gauge movement consists of two primary coils, one of which is wound at a 90 degree angle to the other one.
^ A primary magnet, to which a shaft and pointer are attached, rotates to align to this primary field, resulting in pointer position.
^ The bobbin/coil assembly is pressed into a metal housing. The bobbin has two holes for dial mounting.
^ There is no adjustment, calibration or maintenance required for this gauge.

Oil Pressure Switch
^ is installed on the engine into an engine oil lubricating passage.
^ reacts to the pressure of the engine oil in the lubricating passage.
^ is normally open and closes with oil pressure.

Charge Indication System
^ voltmeter gauge
^ generator (GEN)
^ charging system warning indicator
^ necessary circuitry
^ The charging system warning indicator will stay on after initial start-up if the battery is not being charged.
^ The warning indicator is controlled by the generator voltage regulator.

Battery Voltage Gauge
^ is identified by a battery symbol.
^ indicates battery voltage when the ignition switch is in the RUN position (ENGINE OFF).
^ is not adjustable and should be replaced if inoperative.
^ the pointer will move to indicate charging system voltage after starting the engine.

Speedometer
The speedometer receives a voltage signal from the vehicle speed sensor (VSS). The VSS is a permanent magnet generator that is driven by the speedometer drive gear inside the transmission. The VSS outputs a frequency that is proportional to the vehicle road speed. The standard speedometer registers to 120 mph, the Mustang GT speedometer registers to 150 mph and the Cobra speedometer registers to 160 mph.

Odometer
The odometer receives a voltage signal from the vehicle speed sensor (VSS).

Odometer Replacement
The mileage on replacement speedometer/odometers cannot be reset by the technician. A speedometer, preset to the correct mileage, is available through designated Ford Motor Co. Service Centers.

The reset button will set the trip odometer to zero. The trip odometer receives a voltage signal from the vehicle speed sensor (VSS).

Tachometer
The tachometer (part of the speedometer assembly) indicates engine speed in revolutions per minute (rpm). The tachometer receives an electrical signal from the powertrain control module (PCM) which is converted to the pointer movement on the rpm scale. The standard tachometer registers to seven thousand rpm, while the GT and Cobra tachometers register to eight thousand rpm.
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