The ECU is a specialized small computer that interacts with and controls various vehicle sensors and solenoids. These sensors and solenoids include the temperature of the motor (Harleys head temperature sensor), outside ambient temperature and pressure (altitude), throttle position (TPS), engine speed (RPM), load (kPA or Manifold Absolute Pressure/MAP), and many more. The ECU processes all this data and makes adjustments so that the vehicle performs as it is programmed.

Interacting with the ECU requires a special protocol or language. For Harley, this is primarily CAN and J1850. PCs generally do not innately support these communication methods, so an intermediate device or "translator" is needed. This is the VCM-TR4 (Vehicle Communication Module). It "translates" information between the computer and the ECUs of the vehicle. So that the user (you) can send and receive data/commands.

Centurion diagnostic tools gives users the ability to interact with these ECUs to improve, repair, or monitor the vehicle