1990 Toyota 4Runner Replace Spark Plug Wires

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The spark plug wires on the 1990 Toyota 4Runner SUV are integral to the vehicle's ignition system. If they're bad, your 4Runner either will run poorly or won't run at all. The spark plug wires transmit electric current from the distributor to the individual spark plugs, which generate sparks to initiate internal combustion. If the spark plug wires are damaged, a spark might jump to a metal part of the engine or otherwise never reach the spark plug. You can change old spark plug wires yourself with just a little know-how. When you're going to change one, you should go ahead and change them all--they come in a set anyway.

Tools Used[edit]

New spark plug wires
Dielectric grease

Replace Spark Plug Wires[edit]

  • Ensure that the vehicle is cool. This will make it easier and safer to work around the engine components.
  • Open the hood and locate the distributor on the driver's side of the engine. You will see the spark plug wires running away from the distributor cap to the individual spark plugs in the engine.
  • Grasp the spark plug wire close to where it connects to the distributor cap and pull it off. Rotate the wire a little to make removal easier, but do not put excessive tension on the wire, which can damage the distributor cap.
  • Follow the wire to its plug, and grasp the wire as close as possible to the engine. Pull the wire off the spark plug, using a slight twisting motion if necessary.
  • Add a small amount of dielectric grease to the new spark plug wire boot and attach the wire to the plug. Twist the wire slightly, if necessary, to seat it fully onto the plug.
  • Route the new wire to the distributor cap, following the path of the old wire. Usually there are plastic brackets into which the wires snap. Attach the wire to the distributor cap by sliding it into place where the old wire was connected.
  • Repeat steps 3 through 6 to replace each of the remaining spark plug wires. Remove then replace one wire at a time to avoid connecting the wrong wire to the wrong plug or distributor cap location.

Tips & Warnings[edit]

  • Dielectric grease is a silicon-based lubricant and preservative that makes the wires easier to attach and prevents corrosion. It's not essential that you use this grease, but it it recommended.