Ignition control module for your car

Your Ignition control module worn out? » Read more about common malfunctions • Repair • Replacement manual

Ignition module for clean combustion

The ignition module is the successor of the traditional ignition, consisting of interrupter and ignition distributor. The ignition module now enables a more precise combustion control in the engine compartment. This is important for meeting exhaust regulations. The component is alternatively being referred to as the ignition control module.

Tasks of an ignition module

The spark plug carries up to 28.000 – 35.000 volt tension. This is necessary to generate an ignition spark strong enough to cause the compressed fuel/air mix to explode. The battery or dynamo supplies 12 Volt which are transformed in the ignition coil. To this end the ignition coil has two windings which have to be switched at exactly the right moment. This is where the ignition module comes in. The ignition module controls the transformation of the 12 Volt from the battery or dynamo up to the necessary voltage for the spark plugs. The essential difference with a traditional interrupter/rotor/distributor principle is, that the ignition module functions without moving parts. Instead of a mechanical switch it has a transistor. This switch functions electronically instead of mechanically. The transistor is initiated by the control unit instead of the ignition module. The control unit waits for a signal providing data on the piston position in the engine. The appropriate sensors are the Hall-sensor or the angle sensor on the camshaft.

Ignition module: construction

Similar to the procedure with an ignition distributor, the primary current of the ignition coil enters the ignition module and is transmitted to the spark plugs. The module consists of a small box of synthetic resin with cooling elements attached to it, and a flat connection bushing for the power supply from the ignition cables. The cooling element is very important: due to its compact and electronic construction the module heats up. Therefore it is always equipped with a aluminium cooling unit. Without it the ignition module would destroy itself by overheating within a few seconds.

Ignition module defects

The ignition module is under high strain due heat as well as the current flowing through which can cause it to burn out. In the worst case this leads to a cable fire. Very likely, this would be the result of a faulty assembly. A failing ignition module leads to a stalling engine. Its malfunction can not be determined from the outside. Reading the error memory will probably identify the defective component. It cannot be repaired and the only solution is replacement by a new part. A defective ignition module is identified by the following symptoms:

• the engine performance is deteriorating
• the check engine light switches on
• the engine stalls

Important issues relating to the installation of ignition modules

Overheating is the main problem for the ignition module. This allows for no errors at assembly. It is important to observe the following details:

• always install the module with thermal grease
• all plugs must be corrosion-free an clean
• always check reference number at replacement. The module must match 100%. Even when the casing looks identical and the contacts and plugs match, the ignition electronics can be different. A wrong module will burn out immediately.

Ultimately all other ignition components must be at least checked thoroughly. This includes measuring the ignition coils and a profound spark plug check. Possibly, the sensitive ignition module has failed due to an external impact. In cars with electronic ignition the coils sit directly on the spark plugs.

Buying a new ignition module

The construction of the ignition module strongly depends on the car type. The actual small module with cooling unit is not necessarily the standard installed component in the car. Often, ignition module, cables and coil form a unit which can only be replaced entirely. As a result, prices vary greatly: simple, separately replaced ignition modules start at 15 EUR (±£13.5). Complete electronic ignition system cost 150 EUR (±£135) or more. Nevertheless no compromises should be made on the ignition. The new unit must match the car 100%, otherwise you run the risk of serious damage, from a defective catalytic converter to an engine fire.