GM Service Manual Online
For 1990-2009 cars only

Adjustment Procedure

Tools Required

J 39200 Digital Multimeter


    Object Number: 55252  Size: SH

    Important: The throttle valve must be in the closed position for correct measurements.

  1. Connect a J 39200 DMM to the TP sensor terminal 1 (3) to 2 (4).
  2. Measure the resistance.

  3. Object Number: 55258  Size: SH
  4. Insert a 0.65 mm (0.026 in) feeler gauge (2) between the throttle stop screw (1) and the throttle lever (3).

  5. Object Number: 55252  Size: SH
  6. With the retaining screws (1) loosely installed, turn the TP sensor (2) fully counterclockwise.
  7. Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  8. Gradually turn the TP sensor clockwise in order to find the position where the ohmmeter reading changes from continuity to no continuity.
  9. Tighten
    Tighten the TP sensor bolts (1) to 2.5-4.5 N·m (22.8-38.4 lb in).


    Object Number: 55258  Size: SH
  10. Remove the feeler gauge. The DMM should still indicate continuity.
  11. Insert the 0.8 mm (0.037 in) feeler gauge between the throttle stop screw (1) and the throttle lever (3). The DMM should now indicate an open circuit (no continuity).
  12. Insert the 0.5 mm (0.020 in) feeler gauge between the throttle stop screw (1) and the throttle lever (1). The DMM should indicate continuity. If steps 6, 7 or 8 are unsatisfactory, return to step 1 and repeat the entire procedure.

Throttle Position (TP) Sensor Check

    Caution: Unless directed otherwise, the ignition and start switch must be in the OFF or LOCK position, and all electrical loads must be OFF before servicing any electrical component. Disconnect the negative battery cable to prevent an electrical spark should a tool or equipment come in contact with an exposed electrical terminal. Failure to follow these precautions may result in personal injury and/or damage to the vehicle or its components.

  1. Disconnect the negative battery cable.
  2. Disconnect the Throttle Position (TP) sensor electrical connector.
  3. Important: There should be more than 2 k ohms difference between when the throttle valve is at the idle position and when it is fully open.

  4. Measure the TP sensor resistance according to the TP Sensor Output Check table below.
  5. If the TP sensor resistance is not within the specified ranges, adjust or replace the TP sensor.
  6. Refer to Throttle Position Sensor Replacement .

  7. If the TP Sensor resistance is within the specified ranges, connect the TP electrical connector.
  8. Connect the negative battery cable.

Throttle Position (TP) Sensor Output Check

Terminals

Throttle Position

Values

Resistance between 1 and 2 (CTP switch)

Throttle lever-to-stop screw clearance is 0.5 (0.020 in)

0 - 500 ohms

Resistance between 1 and 2 (CTP switch)

Throttle lever-to-stop screw clearance is 0.8 (0.031 in.)

Infinite

Resistance between 1 amd 4

--

3.5 - 6.5k ohms

Resistance between 1 and 3

Idle Position

0.3 - 2k ohms

Resistance between 1 and 4

Wide open throttle

2 - 6.5k ohms