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Spark plug wires from NGK are built for performance applications and visual appeal. NGK manufactures the wires to meet or exceed original equipment manufacturer specifications. A wire winding within the plug wire suppresses radio frequency interference generated whenever current passes through a wire. This RFI suppression prevents interference with the electronic engine controls. As the wires go bad, they lose the ability to suppress RFI and deliver ignition spark to the plug. Test the wires for continuity, resistance and proper operation.

Instructions

1

Remove the spark plug wire from the distributor and spark plug by grasping the boot at the end of the wire, twisting slightly and pulling to disconnect it.

2

Inspect the connectors on the wire within the spark plug and distributor boots. The connectors should be free of corrosion and moisture with no apparent distortion or discoloration.

3

Set a multimeter to check for resistance or ohms in the x100 range. Resistance is indicated by the Greek omega symbol. Turn the selector knob or scroll down through the options until the proper range is set.

4

Insert one of the meter probes in the distributor boot and the other probe in the spark plug boot on the wire. Make certain you have good contact between the probes and the connectors. Read the meter display. The display should read between 1,500 and 2,500 ohms of resistance per foot of wire. A reading more than 6,000 ohms per foot indicates a bad wire. NGKs low-resistance wires may have significantly less resistance, such as its Power Cable wires rated at 270 ohms per foot.

5

Grasp the plug wire by the boot and reconnect it to the distributor. Install a known good spark plug in the spark plug boot of the wire. Hold the threaded part of the spark plug against the engine block or a grounded area of the frame. Have a helper start the engine; inspect the spark produced by the plug. The spark should be blue with a strong audible report, or popping, as it fires. An orange spark with a weak report may indicate bad wire connectors.

6

Turn off the engine and remove the test plug. Grasp the plug wire by the boot and reconnect it to the spark plug installed in the engine. Firmly press the wire onto the plug and make certain it snaps into place.

7

Replace the plug wire if it fails the test in Steps 2, 4 or 5.

The VTEC solenoid transforms electrical energy into mechanical energy. Signs of a faulty solenoid include a loud screeching sound from the engine, a sluggish or slow engine and the appearance of the "Check Engine" light. You can test the solenoid if you suspect it isnt working properly. If its not in working condition, you must replace it.

Instructions

1

Turn the ignition to the "On" position.

2

Connect a 12-volt battery to the solenoid wire, and ground the housing. If the solenoid is in working condition, you should hear a clicking sound. If you do not hear a clicking sound, you should ensure a proper connection between the solenoid wire and the ECU.

3

Ensure a proper connection between the yellow solenoid wire and connector "A17" on ECU "A."

4

Drive the vehicle. If the engine seems sluggish or makes loud sounds, turn off the vehicle and replace the faulty solenoid.

A head gasket creates the seal between the engine block and head. A cylinder head gasket leak test is a method of determining if the head gasket has failed without removing the head and visually inspecting the gasket.

Method

A cylinder leakage tester and air compressor are required to perform a cylinder leak test. A threaded insert is attached to the spark plug hole and an air gauge, then air is pumped via the compressor into the cylinde. A cylinder leak is determined by monitoring the gauge for pressure loss.

Locating the Leak

There may be various causes for a cylinder pressure leak. During the test, listen and feel for the escaping air to determine the source. Air gurgling through the radiator is the typical sign of head gasket failure. However, a cracked head may also cause air leaks into the radiator.

Alternatives

In addition to the cylinder leak test, there are other methods of testing for a defective head gasket. The cooling system can be pressure checked using a cooling system pressure tester. A block checker is another device that can test the head gasket. The block checker reacts to exhaust gases in the cooling system which indicates a leak.

The ignition switch in your 88 Cherokee carries the signal that is initiated by the operator of the vehicle to the starter. The starter then turns over the engine and starts your Cherokee. If you have been encountering difficulty when you go to turn over your engine, you should perform an ignition switch test. If you can no longer maintain a continuous flow of power to the interior lights, gauges or radio in your Cherokee, you should also perform this test to help you diagnose potential problems with the switch.

Instructions

1

Locate the fuse block below the dash on the left side of the brake and clutch pedals.

2

Pull the plastic cover off the fuse block and locate the fuse for the ignition; it is the first fuse on the top left side of the fuse block.

3

Pull the fuse straight out to unplug it from the fuse block.

4

Inspect the fuse for damage. If you notice corrosion at the metal base piece of the fuse, replace it with a new fuse.

5

Prop open your hood and rotate the multimeters knob until it sits at the "Volts" setting. A multimeter measures electrical voltage, current and resistance through digital or analogue meters. Some multimeter models additionally read temperatures, inductance, frequencies, capacitance and duty cycles.

6

Hold the red probe on the multimeter to the positive port on your battery. Hold the black probe on the multimeter against the frame of your Cherokee. A working battery will provide a voltage reading of 12.6 volts on the multimeter. If you read any voltage amount less than 12.6 volts, replace your battery.

7

Insert your key into the ignition switch and turn it to start your engine. If the engine starts, you do not have a problem with the ignition switch. If your engine does not start, listen for a single-click sound as you rotate the key to the "III" mark. If you do not hear this sound, you need to replace the ignition switch because it is broken.