Instrument Cluster - New Magnetic Gauge System
86ford24 Article No. 86-2-5INSTRUMENT CLUSTER - DESCRIPTION OF NEW MAGNETIC GAUGE SYSTEM FOR 1986
FORD 1986 TAURUS
LINCOLN-MERCURY 1986 SABLE, MARK VII
LIGHT TRUCK 1986 AEROSTAR
The instrument cluster for the 1986 Taurus/Sable, Mark VII LSC, and Aerostar carlines incorporates a new magnetic gauge design for indication of fuel, coolant, temperature and engine oil pressure with improved reliability and accuracy that operates differently than previous bi-metal gauges in the following manner:
^ After the ignition is turned off the gauge pointer will stay in its approximate operating position.
^ The fuel gauge pointer may show some movement during normal maneuvering due to fuel movement in the tank.
FIGURE 5:
Construction and Operation
(Refer to Figure 5)
The new magnetic gauge movement consists of three primary coils (R1, R3, and R4), one of which is wound at 90~ to the other two. A fourth calibration coil (RC) is wound in parallel to (R1). The coils form a magnetic field which varies in direction according to a variable sender resistance which is connected between two of them; as the sender resistance varies, the ratio of currents in the coils changes, thereby changing the resultant magnetic field produced by the coils. 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 or calibration on the gauges. No maintenance is required.
NOTE: There is no IVR in this gauge system.
Advantages
^ More reliable due to elimination of instrument voltage regulator and a highly automated process.
^ Improve system accuracy due to elimination of instrument voltage regulator and a highly automated calibration process for the gauge.
^ Fewer parts than current bi-metal gauge system.
^ Allows greater styling flexibility for gauge travel.
^ Smaller package which allows for dial graphics to be backlit easier.
^ Higher torque allow use of heavy plastic lit pointers.
^ Allows the utilization of a common linear fuel sender output between magnetic gauges and electronic gauges thus simplifying electronic gauge circuitry.
^ Basic magnetic-type movement can be utilized for future manufacture of tachometers, electric speedos and voltmeter.
^ Use of present production coolant temperature and oil pressure senders.
^ ELFW - solid state board mounted to the instrument cluster P.C.
FIGURE 6:
Magnetic Gauge Electronic Low Fuel Warning Assembly (Available on Taurus/Sable)
(Refer to Figure 6)
The magnetic fuel gauge system required a new Low Fuel Level Warning Switch Assembly (ELFW). The new ELFW is all solid state and does not require housing or wiring connector. It mounts directly to the instrument cluster backplate and makes electrical connection to cluster printed circuit pads via flexible terminals that scratch through any oxide build-up. There is no provision for adjustment of calibration. It is set to switch the indicator warning lamp on when the fuel level reaches approximately 1/8 tank. It contains a one minute electronic filter to prevent erratic switching due to fuel movement in the tank. The filter prevents the ELFW from providing a momentary lamp prove out after initial ignition start up like the former bi-metal warning assembly.
OTHER APPLICABLE ARTICLES: None
WARRANTY STATUS: "INFORMATION ONLY"