Code P021, Shorted Throttle Position (TP) Sensor: Notes
WARNING: This page is about a different car, the 1995 Cadillac DeVille. However, it is still accessible from the selected car via links, so may be relevant.
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 ground 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.