Code P021, Shorted Throttle Position (TP) Sensor Circuit: Notes

TP sensor is a potentiometer. A 5-volt reference is provided on circuit No. 474 and ground is provided on circuit No. 808. TP sensor signal circuit No. 417 varies between zero and 5 volts based on throttle plate position. At low throttle angle, TP sensor signal voltage is low. PCM uses TP sensor information to determine idle, WOT, deceleration leanness and acceleration enrichment. Code P021 sets when PCM detects a TP sensor signal that is too high.