* Complete No Start: This is the most common symptom. The engine cranks normally (starter motor works), but it won't fire up because the ignition module isn't sending the necessary signal to the ignition coil(s).
* Intermittent Starting/Running: The car might start sometimes and then die unexpectedly, or it might run rough and stall frequently. This is often due to a failing ignition module that's intermittently providing a signal.
* Misfires/Rough Running: If the module is partially failing, the engine might run but very roughly, with noticeable misfires. This is because the spark to one or more cylinders is weak or inconsistent.
* No Spark: Testing the spark plugs would reveal no or weak spark at the plugs. This is a direct result of the ignition module's failure to properly distribute the high voltage needed for ignition.
It's important to note that these symptoms can sometimes be similar to other problems, such as a faulty crankshaft position sensor, distributor issues (if equipped), ignition coil problems, or even a bad fuel pump. A proper diagnosis involving testing with a multimeter or a scan tool is necessary to pinpoint the exact cause.
