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In 1988, BMW was the first auto maker to introduce an electronic throttle control system which would set a benchmark for future developments of electronic throttle control, also known as drive by wire. While previous generations of vehicles used a mechanical throttle cable attached to the carburetor or throttle body, the new design (which is now an industry standard) uses an electrical signal to several sensors that control the throttle response.
When the accelerator pedal is pressed, a sensor on the pedal sends the pedal position to the electronic throttle actuator on the throttle body to indicate how much fuel should be introduced into the engine. The power provided to the electronic throttle actuator is regulated by the actuator relay in the underhood fuse panel. It acts as a switch, sending power to the throttle actuator when it is required. The amount of power is determined by accelerator pedal position, the powertrain control module, and the ignition position. If the electronic throttle actuator relay is not switching as it should, the Check Engine light will illuminate, and the throttle will not be responsive when the accelerator pedal is pressed. Some manufacturers have experienced problems with moisture in the actuator relay, which in freezing temperatures can cause similar symptoms.
The electronic throttle actuator relay will only need to be checked or replaced if there is a suspected problem. If the electronic throttle actuator relay fails, is working only intermittently, or if you experience related symptoms, have the drive by wire system diagnosed and repaired by one of our expert technicians.
A failing electronic throttle actuator relay can leave you stranded without throttle response in traffic or undesirable cold weather conditions. Have the actuator relay replaced as soon as it fails, even if intermittently.