21 TP Sensor Circuit - Voltage Out of Range High

From SaturnWiki
Jump to: navigation, search


The throttle position sensor (TPS) is variable resistor that is connected to a five volt reference source, a ground, and an input signal at the PCM. When the throttle plate is closed, the sensor input voltage will be low and increase as the throttle is opened. The TPS is mounted on the throttle body and connected to the throttle shaft which is controlled by accelerator movement.

Code Parameters

Code 21 will set if:

  • The PCM sees TPS voltage over 4.9 volts.

Diagnostic Aids

  • When attempting to diagnose an intermittent problem, use the Scan Tool to review supplemental diagnostic information.
    • The supplemental data can be used to duplicate a problem. Select MALF History from Scan Tool EC menu.
  • Voltage can be read on wires without disconnecting any connectors.
  • Check the tightness of the female terminal grip with a spare male terminal.
  • Normal voltage readings should vary smoothly from 0.4 volts to 4.7 volts +/- 0.2 volts as the throttle is moved from closed to wide open position.