In a spark ignition system, the control module plays a pivotal role in managing the ignition process by providing the necessary signals to ignite the fuel-air mixture. If the control module is faulty, it may not send the correct spark timing or intensity to the ignition electrode, which can lead to improper or failed ignition. This failure can manifest as delayed ignition, misfires, or continuous operation without ignition.
While a defective gas valve could prevent the proper flow of gas, and a blocked vent could lead to inadequate combustion air or unsafe conditions, these issues would not specifically relate to the ignition spark itself but rather to the availability of fuel or airflow. Similarly, a defective thermostat could affect the overall system control but would not directly impact the ignition process the way a malfunctioning control module would.
Understanding the functions of each component emphasizes why a faulty control module is the most likely source of improper ignition in a spark ignition system.