How Does the Audi Ignition Control Module Work?

Audi ignition control modules are the firing control for the coil packs. On a V-6 engine, there are three coil packs. The ignition control module is attached beneath them. It has a brown electrical harness connector with five wires. The ignition control module is essentially a grounding station for the coil packs. It receives power from the ignition through the number 1 wire to the left as you face the module. The second from the left is the ground wire, and the other three wires are for the coils.

The ECM receives input from the crankshaft sensor. The input tells the ECM the position of the crank relative to top dead center on the number 1 piston. It takes a coolant temperature reading from the coolant temperature sensor to determine the amount of advance or retard needed of the spark.

The intake temperature sensor senses the temperature of the air entering the intake manifold and the mass air flow sensor which indicates the air density, be it high as in a low altitude or cold air or low density as in a high altitude or very hot day. The ECM, using these readings, compiles a plan of action to best suit the circumstances.

The module controls the fuel injector on-time through the injector drivers in the computer and sends a signal to the ignition control module, as to the amount of advance or retard to use in the ignition spark control. The ignition control module assimilates this information and reacts by grounding or firing the appropriate coil at the right time.

There are three coils and six cylinders. Each coil fires two spark plugs simultaneously--one spark is for the purpose of ignition at the appropriate moment, and the other is firing on an exhaust stroke on another cylinder. This is called the wasted spark system.

Should a problem present itself, such as a no start and confirmed no spark condition, hook a voltmeter's positive lead to the first wire on the left. Hook the negative lead to a good ground. With the key on, there should be battery voltage. If not, check fuses and then the wire to the computer. If there is battery voltage, the computer is most likely bad. If there is voltage, move the positive lead to the second wire, which is the negative signal from the computer. Turn the engine over and watch the voltmeter to duty cycle or pulse. Every time the computer commands the ignition control module to fire a coil there will be a pulse. If there is no pulse, the wire to the computer, the computer's personal ground or computer is bad. If there is a pulse, then the ignition control module is bad and can be replaced separately.