Throttle Position (TP) Sensor

A malfunction in the throttle position sensor circuit will set diagnostic trouble Codes 21 and/or 22. For testing and adjusting procedures, see THROTTLE POSITION (TP) SENSOR in ADJUSTMENTS article in this section. Use the following procedure to diagnose TP sensor.
Using ohmmeter, measure resistance or continuity of throttle position sensor between designated terminals with selected feeler gauge thickness between throttle lever and stop screw. See Fig 1 . Adjust or replace TP sensor if resistance is not within specification. See THROTTLE POSITION (TP) SENSOR RESISTANCE table.

Fig 1: Identifying TP Sensor Terminals

Courtesy of GENERAL MOTORS CORP.

THROTTLE POSITION (TP) SENSOR RESISTANCE

Application

Ohms

Standard Emissions

Between Terminals 1 & 2 ⁽¹⁾

0-5000

Between Terminals 1 & 2 ⁽²⁾

Infinity

Between Terminals 1 & 2 ⁽³⁾

0-5000

Between Terminals 1 & 3 ⁽³⁾

240-1140

Between Terminals 1 & 3 ⁽⁴⁾

3170-6600

Between Terminals 1 & 4

4370-8130

Upgraded Emissions

⁽⁵⁾

⁽¹⁾	With .012" (.30 mm) feeler gauge installed between throttle stop screw and lever.

⁽²⁾	With .035" (.89 mm) feeler gauge installed between throttle stop screw and lever.

⁽³⁾	Throttle valve at idle position.

⁽⁴⁾	Throttle valve at fully open position.

⁽⁵⁾	For information on TP sensor, see THROTTLE POSITION (TP) SENSOR in ADJUSTMENTS article in this section.