Electronic Throttle Body Throttle Position Sensor (ETBTPS)

Description and Operation 1-21

Engine Control Components

Typical Inline Electronic Throttle Body TAC Design Typical Parallel Electronic Throttle Body TAC Design

Electronic Throttle Body Throttle Position Sensor (ETBTPS)

The ETBTPS has two signal circuits in the sensor for redundancy. The redundant ETBTPS signals are required for increased monitoring. The first ETBTPS signal (TP1) has a negative slope (increasing angle, decreasing voltage) and the second signal (TP2) has a positive slope (increasing angle, increasing voltage). The two ETBTPS signals make sure the PCM receives a correct input even if one signal has a concern. For Fiesta, there is one reference voltage circuit (ETCREF) and one signal return circuit (ETCRTN) for the sensor dedicated to the ETBTPS. For all others, there is one reference voltage circuit (ETCREF) and one signal return circuit (ETCRTN) for the sensor shared with the reference voltage circuits (APPVREF1 and APPVREF2) and signal return circuits (APPRTN1 and APPRTN2) used by the APP sensor. For additional information, refer to Torque Based Electronic Throttle Control (ETC) in this section.

Engine Coolant Temperature (ECT) Sensor

The ECT sensor is a thermistor device in which resistance changes with temperature. The resistance of a thermistor decreases as the temperature increases, and the resistance increases as the temperature decreases. The varying resistance changes the voltage drop across the sensor pins and provides electrical signals to the PCM corresponding to temperature.

Thermistor type sensors are considered passive sensors. A passive sensor is connected to a voltage divider network so varying the resistance of the passive sensor causes a variation in total current flow. Voltage that is dropped across a fixed resistor (pull-up resister) in series with the sensor resistor determines the voltage signal at the PCM. This voltage signal is equal to the reference voltage minus the voltage drop across the fixed resistor.

The ECT sensor is located in an engine coolant passage and measures the engine coolant temperature. The PCM uses the engine coolant temperature input for fuel control and for cooling fan control. The ECT sensor can be a threaded or twist lock type.

Typical Threaded ECT Sensor

Evaporative Emission (EVAP) Canister Vent Valve

The EVAP canister vent valve (located near the EVAP canister) is part of the enhanced EVAP system controlled by the PCM. During the EVAP leak check monitor, the EVAP canister vent valve seals the EVAP canister from the atmospheric pressure. This allows the EVAP purge valve to achieve the target vacuum in the fuel tank during the EVAP leak check monitor.

2016 Powertrain Control/Emissions Diagnosis, Gasoline Engines, 3/2015