How to Replace an Ignition Control Module

by Dan Ferrell

The ignition control module in your vehicle controls ignition spark sequence and fires the ignition coil as well. However, this electronic component is very sensitive to heat. Since many vehicle models locate their modules inside the engine compartment, it is not unusual for these components to succumb eventually. But whatever your vehicle model, follow these steps to replace the control module in your car.

Park your vehicle in a safe place and locate the ignition module.

Look under the dashboard. If yours is mounted here, unplug the module wiring harness. Remove the mounting bolts using a Phillips screwdriver or ratchet and socket. Replace the old unit with the new module and install the mounting bolts. Plug the wiring harness.

Open the hood and remove the distributor cap using a Phillips screwdriver or ratchet and socket, but do not disconnect the spark plug wires from the distributor cap. Some ignition modules are mounted inside the distributor. Unplug the electrical connector from the module and remove the mounting bolts using a Phillips screwdriver or ratchet and socket. Replace the old module with the new unit and install the mounting bolts. Replace the distributor cap.

Look on one side of the distributor. Some modules are attached to the outside case of the distributor. Mark the exact mounting location of the distributor base on the engine so you can reinstall the distributor at the same exact location to avoid disturbing the engine timing. Remove the distributor cap using a Phillips screwdriver or ratchet and socket, but do not remove the spark plug wires. Remove the distributor mounting bolts and lift the distributor off the engine compartment. Remove the ignition module mounting bolts and install the new module in place. Install the distributor on the engine following the match-mark and install the distributor cap.

Look for the ignition coil and module assembly. Follow the spark plug wires starting at the spark plugs. The wires connect to the coil and module assembly, which may be mounted on the back of the engine. You might have to raise the front of your car using a floor jack and safely support it on two jack stands. Reach under the engine and unplug the coil assembly electrical connectors. Remove the assembly mounting bolts using a ratchet and socket. Remove the assembly from the engine and remove the coils using a ratchet and socket. Remove the old ignition module from the base plate and install the new unit. Install the coils and module assembly on the engine. Plug the electrical connectors and lower the vehicle.

Tip

  • check Consult your owner's manual or vehicle service manual to identify or locate components. You can buy one at most auto parts stores or consult one for free at most public libraries.

Warning

  • close Most ignition control modules require a coat of silicone dielectric grease on the back of the unit prior to installation. The grease protects the module from overheating and circuit damage. Follow the manufacturer's instructions when installing the module on your particular vehicle.

Items you will need

About the Author

Since 2003 Dan Ferrell has contributed general and consumer-oriented news to television and the Web. His work has appeared in Texas, New Mexico and Miami and on various websites. Ferrell is a certified automation and control technician from the Advanced Technology Center in El Paso, Texas.