An ignition control module is responsible for correct ignition timing. Its improper operation can lead to a number of problems:
Your check engine light turns on
If your vehicle is equipped with an engine control module, it will turn on the check engine light once it determines any problem related to the ignition control module.
Rough running or misfiring
A faulty ignition module will result in incorrect ignition timing which leads to incomplete combustion and misfires. The latter will affect performance at higher speeds.
Your engine stalls
Misfires and incomplete combustion due to a malfunctioning ignition control module will cause the engine to run harder, so it may stall, especially, at low speeds.
Inability to start the engine
An engine needs spark to start the combustion process. If your ignition control module fails, no spark will be generated.
Driving with a malfunctioning ignition control module can cause damage to your catalytic converter.
How the ignition control module works
While most modern vehicles rely on an engine control unit to provide and control ignition timing, older cars and trucks use an ignition control module for this purpose.
The primary job of the ignition control module is to fire each spark plug at the right time for smooth engine running. To make this happen, the ignition control module uses signals received from the crankshaft position sensor and the camshaft position sensor. On newer vehicles equipped with both ignition control module and engine control unit, the sensors’ signals are received by the ECU which controls ignition module operation.
Turbocharged, supercharged and other high-performance vehicles may utilize more complex ignition timing systems needed for their efficient operation.
Ignition control module troubleshooting
The design and location of the ignition control module may vary depending on the vehicle. On some vehicles, it is housed inside the distributor, or the ignition coil assembly, or comes as a standalone device. As a rule, an ignition control module is easy to access, however, sometimes it is located deep inside the engine compartment.
Symptoms caused by other engine problems can be misinterpreted as signs of a failed ignition control module, which is why a thorough diagnosis is recommended before replacing your module.
While most ignition failures are easy to diagnose with an ignition module tester or a spark tester, some of them involve more complex tests. If so, a qualified technician will help you out with that.