Instrument Cluster - Shop Manual Revision
Article No. 86-18-4INSTRUMENT CLUSTER - ANALOG
- REVISED SHOP MANUAL INFORMATION (SYSTEM DESCRIPTION AND DIAGNOSTIC INFORMATION)
LINCOLN-MERCURY 1986 MARK VII
This article is being published to update the Shop Manual information for the Mark VII LSC analog instrument cluster.
The electro-mechanical (analog) instrument cluster consists of an electric analog speedometer/odometer, an electric tachometer, a magnetic fuel gauge and a magnetic temperature gauge. The cluster also contains a high beam indicator lamp and turn signal lamps. Mounted on the rear of the instrument cluster is an electronic message center interface module which inputs a fuel level signal to the DTE (Distance To Empty) function on the Message Center (Tripminder).
Electric Analog Speedometer
This speedometer has a rotating pointer speed dial and total and trip odometer rolls identical in appearance to a conventional mechanical cable driven unit. However, speed and mileage information are provided from a transmission mounted sensor via circuit #150. The typical output of this speed sensor is 0.6 to 20 volts AC over the range of the vehicle operating speed. Additional electrical connections are from the ground circuit #57 and the +12.0 volt circuit #640 from the ignition switch.
The speed indicator is a moving coil type gauge, similar to a tachometer movement, and is sensitive to the frequency of the input signal from the sensor. An 8000 Hz frequency will indicate 60 mph (or 96 km/h).
The odometer rolls are driven by a stepper motor through a gear train. It senses total pulses and will indicate one mile travel per 8000 pulses (or 1 kilometerper 6250 pulses).
Electric Tachometer
The cluster contains a conventional electric tachometer for an 8 cylinder engine. The total scale reading is 6000 RPM. It has three electrical connections: 1) circuit #57, ground; 2) circuit #640, +12 volts from the ignition switch; and 3) circuit #11, tach signal from the tachometer connection on the ignition coil.
Tripminder Interface Module
The Tripminder Interface Module is mounted on the rear of the cluster and consists of a small printed circuit board with components and connector soldered to it. Electrical connection with the instrument cluster circuits is made when located and mounted with a screw.
The four electrical connections are: 1) circuit #295, +12 volts; 2) circuit #89, ground; 3) circuit #204, fuel sender;
4) circuit #205, Message Center.
Fuel Gauge
The fuel gauge is a magnetic 90 degree travel gauge with three input circuits; 1) circuit #640, +12 volts; 2) circuit #57, ground; and 3) circuit #29, fuel sender. This gauge does not return to zero in the "ignition off" state but may drift from the last readings when the ignition is not "on".
The fuel sender on this application is unique, having separate signals to the Tripminder Interface Module and to the magnetic fuel gauge.
Temperature Gauge
The temperature gauge is also a magnetic gauge similar to the fuel gauge, but receives its signal input from the temperature sensor circuit #39.
Figure 14:
Diagnostics
The electric analog speedometer is serviced as a assembly and may not be disassembled for repair. Refer to Figure 14 for instrument cluster electrical connector circuits and voltages.
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WARRANTY STATUS: "INFORMATION ONLY"