The ignition coil plays a very important role as it provides the high voltage needed by the ignition system to fire the spark plugs. It serves as a high voltage transformer, stepping up the ignition system's primary voltage from 12 volts to thousands of volts. Here are some tips on how to diagnose and troubleshoot a faulty Mazda Tribute 2WD V6 ignition coil.
Heat and vibration can damage the coil's primary or secondary windings, causing shorts or opens. If a coil has battery voltage at its positive terminal and it is being grounded on and off by the ignition module or circuit but it is not producing a spark, the coil is defective and needs to be replaced. If the ignition module has failed more than once, it may be due to a bad ignition coil. Shorts in a coil, also known as internal arcing, can overload and damage the circuitry inside the ignition module.
When a coil failure occurs on a distributor ignition system, it affects all cylinders, causing the engine to not start or misfire badly when under load. However, a misfire code can be caused by an ignition, a fuel, or a compression problem, so don't jump to conclusions like assuming that a misfire means a bad coil, spark plug, or plug wire. You see, this symptom might also indicate a bad injector or a compression leak.
If the coil is shorted or open, a code may also be set for the coil on that cylinder; however, if there is no code, you should measure the coil's primary and secondary resistance with a digital ohmmeter. Inspect the spark plug to see if the misfire is due to carbon or oil buildup. Also, check the plug wire to make sure the wire's resistance is within specifications.
If all three (coil, spark plug, and plug wire) appear okay, the misfire may be due to a dirty or dead fuel injector. Check the injector's resistance and voltage supply and use a NOID light to look for a pulse from the powertrain control module (PCM). If the injector seems to be okay, identify whether the cylinder has a bad valve or a leaky head gasket by doing a compression check.