The ignition system must operate for your engine to run. If this system has issues, the engine can stall without warning or refuse to start altogether. In this guide we will go over the popular reasons of the entire ignition system to shut down. If you're having problems with just one cylinder, please use this ignition system testing guide.
By far, the most popular reason for an engine to lose spark is a crankshaft position sensor failure. This sensor is responsible for sending feedback information to the engine computer which produces a trigger signal to each coil at the correct time which ignites the fuel air mixture. Most of the time when this sensor fails it will not leave a trouble code, the engine computer just assumes there is a mechanical problem which is not rotating the reluctor on the crankshaft.
All ignition systems have a separate fuse that sends power to the ignition coil system, anytime you lose spark the first thing to check is the fuse, which is located in the fuse panel under the hood. If its not clear which fuse it is, please ask one of our experts to help find it in the engine control wiring diagrams.
If the fuse is blown chances are you have shorted ignition coil, but even if the fuse is okay this can still be the problem even on multi-coil systems. This is because the short can "shut down" the coil drivers inside the engine computer. Remove the ignition coils and test, begin by set your multimeter to Ohms. Touch the positive (+) and negative (-) terminals of the coil. The resistance should be between 0.4 - 2.0 ohms (varies by manufacturer). If it's out of range or infinite, the coil is bad.
If this relay fails to supply power to the engine computer there will be no spark. Here are the names of the relay which may vary from each manufacturer.
You can test the relay, by following this guide or just swap it out for a new one.
Some cars have an ignition control module while other have it "built in" to the engine computer. While receiving a signal from the engine computer it then outputs the "trigger" signal to the ignition coils, (This module is basically an amplifier). When this component fails the result is a "no spark" condition.
Depending on the application, if a camshaft sensor goes bad it can cancel the output signal of the crankshaft sensor not allow the engine computer to receive the ignition signal. If you suspect this issue simply unplug the camshaft sensor and then re-test for spark.
Some manufacturers have a trouble code for the failure of the engine computer coil drivers such as:
Unfortunately some manufactures do not have a trouble code for when the engine computer goes out, the solution is to swap the computer out for a rebuilt, reprogrammed unit.
A set of mechanical electrical points act as a "trigger" of the coil and can wear down closing the "dwell" setting and stopping the spark from occurring.
The ignition rotor spins acting as a pointer to each cylinder inside the distributor cap, when this part goes bad the ignition spark from the ignition coil grounds to the distributor shaft effetely canceling the spark.
When a ignition coil wire goes bad it can burn up internally with no signs of problems for the outside of the wire creating an open circuit and no spark.
From the ignition coil to the rotor there is the distributor cap, much like the coil wire once the connection is burned it will stopping the continuity between the coil and rotor.
Please watch this video of the job being done to glean additional helpful information.
This guide knowledge base was created by the 2CarPros Team, and by Ken Lavacot: Automobile repair shop owner and certified master automobile technician of over 30 years. If you have question or need help please ask one of our experts we are happy to help. Please visit our 2CarPros YouTube Channel.