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Jeep Grand Cherokee 1993-1998: How to Replace Distributor Cap and Rotor

The distributor cap transfers the electricity from the ignition coil to each engine cylinder. Inside the cap is the rotor. When the rotor and distributor cap connections align, a spark is created at the spark plug.

By Weston Chadwick - October 14, 2015
Contributors: David Prokity

This article applies to the Jeep Grand Cherokee ZJ (1993-1998).

Inside the distributor cap are metal contact points that correspond to each cylinder on your engine. At the top of the distributor shaft is the rotor. This component spins with the distributor shaft—which is splined to the camshaft—to time the spark plugs' ignition. When the rotor and distributor cap contact pass by each other, electricity arcs and travels through the spark plug wires.

Electricity generates heat, which creates wear at these contact points. Over time, the points will build with carbon and the gap between them will increase. This results in misfires and poor engine response to throttle input.

Materials Needed

  • Gloves
  • Safety glasses
  • 10mm wrench
  • 6mm, 7mm, and 8mm sockets
  • 1/4" ratchet
  • 1/4" extension (3"- 6")
  • Spark plug boot puller (optional)
  • Sharpie
  • Masking tape

Step 1 – Disconnect the negative battery cable

Loosen the negative battery cable (black) with a 10mm wrench or socket, and then wiggle/pull it off the battery terminal. Place the cable in an area where it cannot come into accidental contact with the terminal. You can wrap the terminal with electrical tape to eliminate the chance of contact.

Figure 1. Unhook the battery terminals.

Step 2 – Number the spark plug wires

Refer to your engine's firing order in Figures 2 and 3, then mark your spark plug wires with a Sharpie and tape.

  • Figure 2. The firing order for the 5.2 and 5.9 liter engines.
  • Figure 3. The firing order for the 4.0 liter engine.

Step 3 – Locate and remove the distributor cap

The distributor on the 5.2 liter engine is at the rear of the engine next to the firewall. On the 4.0 engine, it will be on the passenger's side. Depending on the tools your using and the amount of clearance, you may want to completely remove the spark plug wires from the distributor cap. Give the spark plug wire boot a firm pull and twist. A removal tool is made for this and is known as a spark plug boot puller.

There is one bolt on each side of the cap. The size is near a 7mm, depending on your year model. Once the bolts are removed, lift up on the cap to remove it. Inside you will see the rotor. It is shaped like a pointer. Pull it up and off the distributor shaft. The rotor is keyed onto the shaft. It can only be installed in the correct position.

    • Figure 4. The distributor cap.
    • Figure 5. The distributor rotor.

Step 4 – Install the distributor cap and rotor

Line the rotor up with the key on the distributor shaft and push the rotor down until it reaches a stopping point. Place the distributor cap onto the distributor and then tighten both bolts, making sure they are not being threaded at an angle. Re-connect the spark plug wires, making sure the number on the wire matches up with the firing order. You will feel the wire "click" onto the post. Re-connect your negative battery cable to complete the installation.

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