JR's Place - JoeCool's 1987 Ford Thunderbird Turbo Coupe - Motor Trend's 1987 Car of the Year

Build Your Own
Custom Instrument Cluster

Electrical Construction and Considerations

Click for BIG pic - dialup beware!

The electrical connection schematic for the cluster shows all wiring for the voltmeter, fuel level, oil pressure, and water temperature gauges, with wiring for the speedometer and tachometer also included. The indicator lamps, such as left and right turn, seat belts, and instrument lights are also shown. All the stock Ford wiring was used to connect the custom cluster to the vehicle's electrical system; no other wires were added or needed with the exception of a new wire for the shift light that is present in the existing cluster but not connected from the factory. The only changes to the vehicle that were required were to remove the stock sending units for oil pressure and water temperature, and to replace them with the appropriate senders that accompanied the Autometer gauges.

If you load the large version of the instrument cluster rear (click on it), you can easily see how the point-to-point gauge connections were accomplished using standard wiring techniques. Also plainly clear is my use of self-adhesive copper tape for lamp connections, which works quite well if you're careful. My ill-fated attempt to use the tape for the connector "fingers" is seen as well. Unfortunately, that idea did not work, and I was forced to remove the "finger" tape and use a separate molex connector for the connections between the instrument cluster and the TC's wiring harness connector, since I had already (insipidly) disposed of the flexible interconnect. See the afterthoughts section for some thoughts on how to connect using the old interconnect to enable use of the existing harness connector with the new instrument cluster.

Instruments Used - Part Numbers - Costs
Instrument Autometer Number Price (Summit)
Speedometer 3988 $207.95
Tachometer 3991 $87.95
Water Temperature 3337 $39.95
Voltmeter 3391 $35.95
Fuel Level 3315 $33.95
Oil Pressure 3327 $49.95
Also used, but mounted in center console
Boost Pressure 3303 $43.95
Air/Fuel Ratio 3375 $51.95

I added the wire for the Shift Light because I plan to hook it up to the computer once I've figured out my new EEC-Tuner. Note that there are no connections to the instrument cluster's connector on pins 5 though 7; those are used for the funky Ford IVR, which is not needed for the Autometer gauges. However, five volts is needed for the System Sentry module so I used a 7805 voltage regulator to obtain that voltage for the module's use. I forgot to label the pinout for the 7805 on the schematic so here's the info: The leftmost connection (that goes to connector pin 1) is the input. The center terminal is ground, and the rightmost pin (connecting to pin 10) is the output. Sorry for the inadvertent omission, folks! The voltage regulator may not be needed (check the Ford schematics) if you don't have a System Sentry module. The capacitors on the input and output lines of the voltage regulator prevent it from oscillating and putting garbage into the car wiring.

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This article will be modified and added to as I have the inclination, so stay tuned!
Click HERE for a directory of all pictures and drawings.

Copyright © 2003-2017 by D. Joseph Frazier
- All Rights Reserved -

Please note that while I've been as careful as possible with this article,
it may contain mistakes. I assume no liability whatsoever for any
detrimental effects using this information may cause to you or your vehicle.

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