Mazda 323/626/929/GLC/MX-6/RX-7 1978-1989

Diagnosis and Testing

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There are several checks, unique to the electronic ignition system, which can be made to locate or repair trouble. The gap between the pole piece and pickup coil can be checked and adjusted, and the electrical resistance of the pickup coil can be checked on most vehicles built through 1982. Although it can be checked, the gap is non-adjustable on the RX-7. The resistance of the ignition coil(s) can be checked on all electronic ignition equipped vehicles.

PICKUP COIL RESISTANCE



1978-82 Vehicles

Unplug the primary ignition wire connector, then insert an ohmmeter between the two prongs of the connector on the distributor side. The resistance of the pickup coil should be 670-790 ohms (GLC) or 720-1,050 ohms (626), as measured at room temperature. If resistance is out of range, replace the pickup coil.

IGNITION COIL RESISTANCE



For ignition coil resistance test procedures, please refer to Engine & Engine Overhaul of this repair guide.

SECONDARY IGNITION CHECK (SPARK TEST)



See Figure 1

  1. Disconnect the high tension lead from the ignition coil at the distributor cap.
  2.  
  3. Wrap a protective cloth around the cable and hold its electrical connector 0.020-0.040 in. (0.50-1.00mm) from a good ground. Have someone crank the engine. The ignition system should produce a plainly visible, bluish/white spark.
  4.  



Click image to see an enlarged view

Fig. Fig. 1: Disconnect the high tension lead from the ignition coil at the distributor cap


CAUTION
A properly operating secondary ignition system can produce enough voltage to give you a nasty shock. Be sure to wrap an insulating cloth around any high tension leads, before grasping them with the engine running or cranking. Better yet, carefully hold the wire using a rubber insulated tool.

  1. Reconnect the high tension lead.
  2.  
  3. If there is doubt about the adequacy of the spark, run the engine until it is hot, then shut the engine OFF and make checks of the coil primary and secondary resistance, as described in Engine & Engine Overhaul in this repair guide.
  4.  

If no spark or an inadequate one is produced, and the coil tests out okay, the igniter and pickup coil may require replacement. However, you should make sure before doing this work that there are no basic maintenance problems in the secondary circuit of the system, since it is often impossible to return electrical parts. We suggest that before you replace the igniter and pickup coil, you carefully inspect the cap and rotor for carbon tracks or cracks, and also check the condition of the high tension wires. Check for cracks in the insulation and measure the resistance of the spark plug wires with an ohmmeter, as described earlier in this section. Resistance should be 16,000 ohms per 3.28 feet (1 meter). Replace secondary parts as inspection/testing deems necessary before replacing the igniter and pickup coil.

 
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