1989 Geo Tracker Base, AutomaticFACTORY OEM SERVICE PROCEDURE

Throttle Position Sensor (TPS)

  1. 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 .
  2. 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)
  3. 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).
  4. 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.
  5. 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
G121587Courtesy 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
G90I14942Courtesy of GENERAL MOTORS CORP.
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