Mazda 323/MX-3/626/MX-6/Millenia/Protégé 1990-1998 and Ford Probe 1993-1997

Diagnosis and Testing


Before beginning any diagnosis and testing procedures, visually inspect the components of the ignition system and check for a possible discharged battery, damaged or loose electrical connections, blown fuses or damaged vacuum hoses. Also inspect the spark plugs for damage and make sure that the coils are properly seated. Check the spark plug towers and boots for signs of poor insulation that could cause spark grounding. Turn all accessories off during diagnosis and testing. Make sure the idle speed is within specification.

The following tools are required; a quality digital volt-ohmmeter, a remote starter and a spark tester for checking the ignition system. A spark tester resembles a spark plug without threads and the side electrode removed. Do not attempt to use a modified spark plug.


2.3L Engine
  1. Remove one of the ignition coils, but leave the 4-wire connector plugged in.
  3. Hold the coil with insulated pliers approximately 0.20-0.39 in. (5-10mm) from a ground.
  5. While holding the coil in position, crank the engine.
  7. A strong blue spark should be seen.
  9. Repeat the test for each of the coils mounted on the engine.
  11. If a spark is seen from some of the coils, and no trouble codes or check engine light is present, proceed as follows:
    1. Replace the faulty ignition coil with a known good unit and test again.
    3. If there is a spark visible, replace the defective coil.
    5. If there is still no spark, check the following ECM terminals for proper voltage (0 volts with ignition switch on, or 0.05 volts with engine idling):

      Cylinder No. 1: terminal 4S
      Cylinder No. 2: terminal 4W
      Cylinder No. 3: terminal 4AA
      Cylinder No. 4: terminal 4AE
      Cylinder No. 5: terminal 4AI
      Cylinder No. 6: terminal 4AM

    7. If the voltages are not normal, inspect and repair the ignition coil related wiring harnesses, connectors, power supply and grounds.
    9. If the voltages are normal, Mazda recommends replacing the ECM. However, due to the cost of an ECM, it is recommends having the vehicle professionally tested with a scan tool designed specifically for the vehicle, before purchasing the ECM for replacement.

  13. If no spark is seen from any of the coils or a trouble code or check engine light is present, proceed as follows:
    1. Check to see if the following diagnostic trouble codes are present (refer to Driveability & Emissions Controls for trouble code retrieval instructions):

      P0335 - CranKshaft Position sensor (CKP) circuit malfunction
      P1345 - SGC signal

    3. If either of the two codes were found, carry out an inspection of the circuits related to the trouble code. Refer to Driveability & Emissions Controls .
    5. If no codes are present, repair or replace the wiring harness connector between the ignition coil and ignition switch.

  15. If a spark is seen from all coils, the system is normal.

1998 2.0L and 2.5L (except Millenia) Engines

See Figure 1

  1. Disconnect the spark plug wires from each spark plug.
  3. Hold the end of the spark plug wire with insulated pliers 0.20-0.39 in. (5-10mm) from a ground. A spark tester may be connected to the plug wire end.

Click image to see an enlarged view

Fig. Fig. 1: To perform a spark test, hold the coil or spark plug wire 0.20-0.39 in. (5-10mm) from a ground and observe the spark

  1. While holding the wire in position, crank the engine.
  3. A strong blue spark should be seen. If there is no spark, the plug wires (refer to General Information & Maintenance ) and the coil pack should be checked.