Theory Of Operation

The Electronic Throttle Control (ETC) system uses two Throttle Position Sensors (TPS) to monitor the throttle blade position. TPS 3 and TPS 4 are located within the Throttle Body Assembly located on engine bank 2. Each sensor has its own Signal circuit (TPS 3 or TPS 4). Both sensors share a common 5-Volt Reference circuit (Supply) and a common Sensor Ground. Each Signal circuit provides the Powertrain Control Module (PCM) with a signal voltage proportionate to throttle blade movement. Normally operating sensor signals are opposing to each other in the following manner:

• TPS 3  voltage starts low, approximately 0.5 volts at closed throttle,  and increases to approximately 4.3 volts at wide open throttle  .
• TPS 4  voltage starts high, approximately 4.5 volts at closed throttle,  and decreases to approximately 0.7 volts at wide open throttle  .