Controller Protector Sometimes we find damage on ECU or controller without having any idea, what the cause is. All electrical circuits are good, but errors appear everywhere. after changing to the new ECU,. all problems are back to normal. Introduce you, controller protector. a device that protects your ECU, controllers or ECM from troubles caused by electrical problems. This device can be used in heavy construction equipment, commercial trucks, and passenger cars. By reducing the possibilities of getting your ECU in troubles, you will increase your business profitability, by reducing downtime, operational cost etc.