Instrument Panel Problem in a 1969 Mustang

Ford Motor Company has produced Mustangs every year since 1964.

Owning a classic muscle car can be an exhilarating experience, but it is often not without some occasional frustrations. In 1969, materials and methods of Ford electric systems and components were somewhat primitive in comparison to more modern rigging. The actual appearance of the circuitry behind the instrument panel might confuse repair efforts, rather than shed any enlightenment. The gauges and indicator lights relied upon for safe operation can display problems that seem to defy logic. There are, as always, devils in the details, but some simple considerations can help get the ghosts out of the instrument panel of your 'Stang.

Running on Empty

Erratic behavior of the fuel and temperature gauge may be the fault of a defective constant voltage regulator, or CVR. The regulator mounted on the back of the instrument panel is meant to cushion electrical inputs to the gauges. It functions to steady gauge readings that otherwise might react constantly to small variables, like sudden fuel movements in the gas tank when accelerating or turning corners. The regulator is no bigger than your thumb, and it can fail in different ways that may render some gauges inoperable or cause improbable readings.

Printed Circuits

Electrical power is distributed to all the gauges and lights of the instrument panel by printed circuits. The metallic pathways are printed on a sheet of plastic and laminated with another sheet of the same material. The layers can separate over time and break the circuits where they pull apart. It may be possible to mend torn circuits with solder or wire, but changes in circuit resistance could damage components or cause an electrical fire in the dash. The most reliable remedy would be to replace the printed circuit plastic panel.

Lighting the Way

The instrument panel lights are powered through the printed circuits and the small bulbs are subject to the same failures you might find in a string of Christmas lights. They can grow dim, or just stop working one by one. The lack of illumination may escape notice until it reaches a point where gauges are impossible to read at night. Some bulbs in certain locations are fitted with covers that color the exhibited light, while others are behind colored lenses, like the turn indicators. Replace all the bulbs at once to ensure even voltage distribution and uniform illumination.

Squeaking By

Speedometer cable maintenance helps ensure longevity.

A squeaking noise in the dash that seems to coincide with a quivering speedometer needle may be caused by the cable that actuates the gauge. The cable is contained in a housing that connects to the back of the instrument panel. When lubrication is lacking, the cable can distort and rub against the housing. Orthodox maintenance procedures require removal at the transmission end of the housing. However, you can disconnect the housing from the back of the instrument panel and spray a lubricant into the open end of the housing. Use the small red pipette, or straw, that comes with a can of cable lubricant to inject the product. Wipe off any excess grease to avoid contaminating the speedometer.

References

• Electric and Electronic Systems for Automobiles and Trucks; Robert N. Brady

Resources

• Mustang Grabber Registry: 1969/1970 Gauge and Interior Differences