How to Change an Ignition Module

by Don Bowman

Ignition control modules have been used for many years. They differ in location but are very similar in function. The ignition control module is located under the coils. There is one coil for every two cylinders on what is referred to as coil packs. Coil packs are common to GM vehicles. On early GM vehicles with HEI distributors, the ignition control module was inside the distributor. Early model Fords had a square-shaped module on the driver's side fender well, which was later transformed into a small rectangular unit attached directly to the distributor.

Removal of the HEI Distributor Module

Remove the air cleaner. Tape and mark the passenger side spark plug wires so they can be installed in their original locations. Disconnect these wires from the distributor cap.

Using a common screwdriver, unlatch the screw locks holding the distributor cap to the distributor housing. Turn each screw until the lower foot moves out from under the housing. Lift the cap off and set it on the driver's side. Detach the rotor using the Phillips screwdriver.

Separate the electrical connector from the flat module lying on the base of the inside of the distributor. The connector has the wires coming through it from the outside of the distributor. Insert the common screwdriver between the connector and module, and twist gently to remove.

Slip out the two small bolts seen on top of the module using a ΒΌ-inch drive socket. Pull the module, keeping it flush with the distributor base, away from the opposite fixed connector to remove the blades.

Reinstall the module by spreading the dialectic grease on the back of the module followed by inserting it again in reverse of removal: Lay it flat and slide the terminals into the fixed connector; insert the bolts; tighten the bolts; then plug in the connector with the wires. Replace the cap and the spark plug wires.

Replacing the GM Coil Pack Base Ignition Control Module

Mark all the plug wires from front to back, using pieces of masking tape and marking them with a pen or marker. Do not mark on the coil itself, because the mark could cause a path to ground that shorts itself out. Remove all the wires.

Pull out the bolts or nuts securing the mounting bracket to the engine. The bolts are in numerous locations but will be obvious, as there are no hidden bolts.

Remove the 7 mm or 8 mm bolt that is at the dead center of the electrical connector on the module. Pull the connector straight out. Pull out the nuts from the module studs that secure it to the bracket. Detach the module.

Pull out all the long bolts securing the coils to the module. Lift off one coil at a time, and disconnect the two electrical connections on the bottom of the coil.

Replace the coils one by one, situating the coil in the same position, and connect the bottom wires and set the coil on the module. Go on to the next one and so on. Replace all parts in reverse order of removal.

Replacing the Ford Fenderwell-Mounted Ignition Control Module

Remove the electrical connector from the module. The module is about 5 to 6 inches square.

Pull out the four bolts securing the module to the fenderwell.

Install the new module and tighten the bolts.

Push the electrical connector into the module.

Replacing the Ignition Control Module on a Ford Distributor

Disconnect the electrical connector on the gray-colored module on the front side of the distributor.

Remove the two bolts securing the module to the distributor, using the special tool for this purpose. It is a round wheel with a deep thin-wall Allen.

Extract the module by pulling it straight down. The terminals on the module are facing straight up.

Install the new module by holding it against the distributor housing under the terminals and pushing the module straight up, inserting the blades into the terminals. Insert the two bolts and tighten. Attach the electrical connector.

Items you will need

About the Author

Don Bowman has been writing for various websites and several online magazines since 2008. He has owned an auto service facility since 1982 and has over 45 years of technical experience as a master ASE tech. Bowman has a business degree from Pennsylvania State University and was an officer in the U.S. Army (aircraft maintenance officer, pilot, six Air Medal awards, two tours Vietnam).