No. 1 Control Box

Control box is common to ignition and air flow circuits as well as the deceleration control system. It receives signals from leading spark plug ignition coil (indicates engine RPM), a thermosensor (indicates engine temperature), and the vacuum switch (indicates engine load). The control box controls trailing ignition, either allowing ignition to fire or preventing it from firing. On automatic transmission models, the condition of the throttle valve also influences the control box.