Nissan 240SX/Altima 1993-1998 Repair Guide

Diagnosis and Testing



See Figure 1

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Fig. Fig. 1: A secondary spark test may be performed using a regular spark plug, attached as illustrated

The best way to perform this procedure is to use a spark tester (available at most automotive parts stores). Two types of spark testers are commonly available:

A Neon Bulb type tester is connected to the spark plug wire, and flashes with each ignition pulse.
The Air Gap type tester must be adjusted to the individual spark plug gap specified for the engine. This type of tester allows the user to not only detect the presence of spark, but also the intensity (orange/yellow is weak, blue is strong).

If a secondary spark tester is not available, a regular spark plug may be used.

  1. Disconnect a spark plug wire at the spark plug end.
  3. Connect the plug wire to the spark tester and ground the tester to an appropriate location on the engine.
  5. Crank the engine and check for spark at the tester.
  7. If spark exists at the tester, the ignition system is functioning properly.
  9. If spark does not exist at the spark plug wire, remove the distributor cap and check that the rotor is turning when the engine is cranked.
  11. If the rotor is not turning, a problem exists in the engine either in the engine or distributor.
  13. If the rotor is turning, perform the spark test again using the ignition coil wire.
  15. If spark does not exist at the ignition coil wire, test the ignition coil, power transistor and related wiring. Repair or replace components as necessary.