How to check an ignition module With multimeter
The ignition module is responsible for turning the coil on and off and for controlling the duration of current flow through the primary winding of the ignition coil. This allows the spark plugs to ignite at a certain time depending on the number of cylinders in your vehicle. An ignition module test can be done using a digital ohmmeter and a 12-volt test light.
Use a wiring diagram for your vehicle’s model year. Locate the terminals running inside and outside the ignition module. Module placement varies from model to model, so check the appropriate vehicle service manual for exact placement.
Connect the ignition and use your voltmeter to check for voltage to the ignition module and the positive terminal of the ignition coil. Place the negative wire of your digital voltmeter on a solid base and use the positive wire to check the wires going to the ignition module and the ignition coil.
If the voltmeter shows that voltage is present at both locations, remove the wires from the voltmeter and set the meter aside. Connect the ground wire of the 12 volt test light to the negative terminal of the ignition coil. Have your partner turn the engine over several times. Your test light should flash. If it does, the module is working properly and no further testing is necessary.
If your test light doesn’t flash, make a visual inspection of the wires going into and out of the ignition module. Look for burn marks, melted wire insulation and wire breaks. Use the wire cutter and splice tool to remove the bad area on the wire and use your wire connectors and the wire cutter and splice tool to repair the bad wires.
Use the multimeter to check for an open circuit condition in the primary coil winding. Touch the negative probe to the negative terminal of the ignition coil, and the positive wire to the positive terminal. Adjust the meter to read the ohms. If the reading shows infinite resistance, the ignition module is defective and must be replaced. Follow the instructions in the service manual for replacing your ignition coil.
Check if the digital voltmeter test shows low or no ohms. If so, then you have a defective ignition module that will need to be replaced. Follow the instructions in your vehicle service manual to replace the module.
Tips
Make sure you have checked all the wires to and from the ignition module as well as the ignition coil. Cables are much cheaper to repair than ignition controls.
Do not touch the ignition circuit wires with your test light. This can cause an excess voltage condition and damage other components.
Warning
Keep all tools and equipment away from the battery. Anything that connects the two terminals can damage the equipment and possibly cause an electric shock.