Ford Tempo/Topaz 1984-1994 Repair Guide

Spark Plug Wires


See Figures 1, 2 and 3

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Fig. Fig. 1: Spark plug wire remover tool

The gasoline Tempo/Topaz is equipped with an electronic ignition system which utilizes 8mm spark plug wires to conduct current to the spark plugs. The boots at the end of the wires are designed to cover the spark plug cavities at the cylinder head end and the distributor contact at the other end. For the ignition system to function properly, a clean contact between the coil and spark plug is necessary. Therefore, regularly inspect the ends of each spark plug wire for signs of corrosion. Also inspect the wires for signs of cracks or breaks in the insulation.

Because the coil and ignition system is capable of producing a large amount of current, never service any ignition component with the car running.


Most spark plugs today are of a resistor type. This means that for them to function correctly, there must be a resistance level between the start of the wire and it's end. With this level of resistance, the spark is of a greater intensity, and therefore the engine is more productive because the combustion is more efficient.

To test the resistance of a spark plug wire, it is necessary to use a multi-meter. This tool is available at most automotive parts stores. Although it is not a cheap tool, it is useful for many electrical situations. It is the only way to test the functionality of resistor plug wires.

When testing plug wires, remove, test and replace one wire at a time.

  1. Remove the spark plug wire, using a twisting motion, from both the spark plug and distributor cap.
  3. Using your multi-meter, set to ohms, connect individual probe ends to respective ends of the plug wire. Record the readings registered on the meter.
  5. The correct resistance should be between 4000-7000 ohms per foot. If the resistance is not within this range, replace the wire.
  7. Continue until all the wires, including the coil wire has been tested.


To avoid confusion when removing or replacing spark plug wires, always remove and tag the wires one at a time.

  1. Carefully inspect the wires before removing them from the spark plug, coil or distributor cap. Look for visible damage such as cuts, pinches, cracks or torn boots. Replace any wires that show sign of damage. If the boot is damaged, it may be possible to replace it by itself.
  3. Carefully grasp and twist the boot back and forth while pulling away from the spark plug. A spark plug wire removal tool (T74P-6666-A or equivalent) can make the job easier.

Do not pull on the wire directly, it may become separated from the connector inside the boot.

  1. Once removed, inspect the inside connection of the spark plug wire. It should be clean metal, usually copper. If corroded, clean with a small wire brush or replace completely.

To install:
  1. Before installing the spark plug wire, coat the inside of the boot and terminal with a thin coat of dielectric compound (Motorcraft D7AZ-19A331-A or the equivalent). Install the wires in their correct order, making certain they fit firmly over the spark plug, coil or distributor.
  3. With all the wires connected, including the wire between the coil and the distributor cap, secure all loose wires using the factory holder installed in the engine compartment.
  5. Start the vehicle to make sure the work was done properly.

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Fig. Fig. 2: Spark plug wire and boot; distributor side

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Fig. Fig. 3: Spark plug wire removed using twisting motion

Spark Plug Boot Replacement

If it is necessary to replace a boot on a particular wire, use the following procedure:

  1. Carefully twist or cut off the old boot. Apply a thin coat of dielectric compound (Motorcraft D7AZ-19A331-A or the equivalent) to the area of the wire that will contact the new boot.
  3. Slowly work the new boot over the spark plug wire, using a twisting motion. (A tool is available for this job. The special tool number is T74P-6666-A).
  5. With the wire and boot secure, reconnect plug wire to plug or cap. Start vehicle to make sure connection is adequate.