Throttle Position Sensor (TPS)

Unplug TPS connector. Close throttle to idle position by applying 18 in. Hg of vacuum to throttle opener diaphragm. Loosen idle speed adjusting screw until screw just makes contact with throttle lever. See Figure .
Insert one of the following feeler gauges between throttle lever and idle screw:
- A/T - .094" (2.40 mm)
- M/T - .086" (2.20 mm)
Connect DVOM between TPS terminals "C" and "D". See Fig 1 . Turn TPS fully clockwise, then turn TPS counterclockwise slowly until DVOM reads continuity. Hold TPS and tighten TPS screws to 30 INCH lbs. (3.4 N.m).
Repeat procedure to verify correct adjustment using resistance readings from THROTTLE POSITION SENSOR (TPS) RESISTANCE table. If TPS cannot be adjusted to obtain the correct values, replace TPS.
Reset idle speed adjusting screw to proper RPM setting. See IDLE SPEED under FUEL SYSTEM in this article.

Fig 1: Identifying Throttle Position Sensor Terminals

Courtesy of GENERAL MOTORS CORP.

THROTTLE POSITION SENSOR (TPS) RESISTANCE

Application Condition

Resistance (Ohms)

Between Terminals C-D

At Idle ⁽¹⁾

0-500

At Wide Open Throttle

Infinite

Between Terminals A-D ⁽¹⁾

3,500-6,500

Between Terminals B-D

At Idle (1)

0-2,000

At Wide Open Throttle

2,000-6,500

⁽¹⁾	To position throttle valve lever to idle position, apply about 18 in. Hg of vacuum to throttle opener valve diaphragm.

Fig 2: Calculating Intake Selective Shim Thickness for Setting Valve Clearance

Courtesy of GENERAL MOTORS CORP.

Fig 3: Calculating Exhaust Selective Shim Thickness for Setting Valve Clearance

Courtesy of GENERAL MOTORS CORP.