Mazda Trucks 1987-1993 Repair Guide

Diagnosis and Testing

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SERVICE PRECAUTIONS



  1. Examine all wiring harnesses and connectors for insulation damage, burned, overheated, loose or broken connections.
  2.  
  3. Be certain that the battery is fully charged and that all accessories are OFF during the diagnosis.

    Always turn the ignition key OFF and isolate both ends of a circuit whenever testing for shorts or continuity.
     
    Never measure voltage or resistance directly at the processor connector.
     
    Always disconnect solenoids and switches from the harness before measuring for continuity, resistance or energizing by way of a 12-volt source.
     
    When disconnecting connectors, inspect for damaged or pushed-out pins, corrosion, loose wires, etc. Service if required.
     

  4.  

PRELIMINARY CHECKS



  1. Visually inspect the engine compartment to ensure that all vacuum lines and spark plug wires are properly routed and securely connected.
  2.  

SECONDARY SPARK TEST



See Figure 1

  1. Remove the spark plug from the engine.
  2.  
  3. Connect the spark plug to the high tension lead.
  4.  
  5. Using insulated pliers, hold the high tension lead and spark plug approximately 0.20-0.39 inch (5-10mm) from a good ground.
  6.  
  7. Crank the engine and verify that there is a strong blue spark.
  8.  



Click image to see an enlarged view

Fig. Fig. 1: Conducting a secondary spark test

 
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