Circuit Description

The Powertrain Control Module (PCM) supplies a 5-volt reference signal and a ground circuit to Throttle Position (TP) sensor, and a signal circuit to monitor changes in throttle angle. TP sensor signal voltage should be about.5 volt at idle and 4.0 volts or greater at wide open throttle. DTC P0121 will set if PCM detects an out-of-range condition.

For duplication of DTC, ensure no active TP sensor or MAP sensor DTCs are present, engine is running, MAP sensor reading is less than 50 kPa or greater than 70 kPa, and predicted throttle angle is not close to actual throttle angle.