Throttle Position Sensor: Adjustments

The TPS is not adjustable. The ECM utilizes the reading at idle for the zero reading, therefore no adjustment is necessary.




*** THIS PROCEDURE HAS BEEN UPDATED BY TSB # 86-B-110, dated 8/86

Some 1986 2.8L engines may experience an erratic idle condition or "SERVICE ENGINE SOON" light that stays on. A voltage test of the TPS circuit must be performed to check the adjustment of the TPS sensor. With ignition on voltage between terminals "A" and "B" with electrical connector connected to sensor should be between .42 and .45 volts. If not replace with part number 17111725 and follow adjustment procedures as outlined below.



Make adjustments, only after the minimum idle speed has been adjusted, or throttle body parts have been replaced.
1. Connect a suitable digital voltmeter from TPS terminals "A" to center terminal "B", or observe scan tool connected at ALDL connector under dash.
2. Turn ignition switch On, engine Off. TPS voltage should read .42-.54 volts.
3. If voltage reading is not to specifications, loosen the TPS retainer screws and adjust TPS sensor to specifications.
4. If proper voltage reading cannot be obtained, replace the TPS sensor.