Throttle Position Sensor: Adjustments

Before the Throttle Position Sensor (TPS) voltage output setting can be accurately checked or adjusted, the idle rpm settings must have been set to vehicle specifications.

TPS adjustment is required only if voltage readings are not within a range of 0.46 ± 0.1 volts. Connect a 10 megohm digital voltmeter such as J29125-A from TPS connector center terminal "B" to bottom terminal "C" (Jumpers for access can be made using terminals 12014836 and 12014837) or use Scan tool. Read TPS voltage, under these conditions:

a. Ignition ON.
b. Engine stopped.
c. Disconnect electrical connector from Idle Solenoid (plunger retracted).
d. Throttle lever against idle speed screw.

If adjustment is required, remove TPS plug to allow adjustment.









PROCEDURE
1. Using a 2 mm (5/64") drill, drill a 1/16" to 1/8" deep hole in aluminum plug covering TPS adjustment screw. Use care in drilling to prevent damage to adjustment screw head.
2. Start a No. 8, 1/2" long self-tapping screw in drilled hole turning screw in only enough to ensure good thread engagement in hole.
3. Placing a wide-blade screwdriver between screw head and air horn casting, pry against screw head to remove plug. DISCARD PLUG.
4. Using tool J-28696, BT-7967 A, or equivalent, adjust TPS screw to obtain 0.46 volts.
5. After adjustment, install new plug (supplied in service kits) in air horn, driving plug in place until flush with raised pump lever boss on casting.

NOTE: Plug must be installed to retain the TPS adjustment screw setting. If plug is not available, remove screw and apply GM 1052624 Threadlock or equivalent to screw threads, then repeat adjustment.

6. Clear trouble code memory after adjustment.