DTC P0123 - Throttle Position (TP) Circuit High Input

NOTE: If DTC P0108, P0113, P0118, P0123 and/or P0450 are set together, Light Green/Black wire (sensor ground) may be open.

Connect scan tool to Data Link Connector (DLC). Turn ignition on. Observe throttle valve opening percentage on scan tool while slowly opening throttle valve to fully open position. If display increases to 96 percent or greater, go to next step. If display reading is less than 96 percent, check for an intermittent problem. See TESTS W/O CODES article.
Turn ignition off. Disconnect harness connectors from TP sensor and ISC actuator. Turn ignition on. Using a voltmeter, measure voltage between ground and Light Green wire at TP sensor harness connector. If reading is 4-6 volts, go to next step. If reading is greater than 4-6 volts, repair short to battery power in Light Green. Retest system.
Turn ignition off. Unplug PCM connector "B". Using an ohmmeter, check for continuity between Light Green/Black wire at TP sensor harness connector and PCM harness connector "B", terminal No. 9. If continuity exists, go to next step. If continuity does not exist, check Light Green/Black wire for an open or poor connection. Repair as necessary. Retest system.
Reconnect PCM connector. Turn ignition on. Using a voltmeter, measure voltage between ground and Light Green/White wire at TP sensor harness connector. If reading is zero volts, go to next step. If reading is 4-6 volts, repair Light Green/White wire for short to Light Green wire. If reading is battery voltage, repair Light Green/White wire for short to battery power. Repair as necessary. Retest system.
Using an ohmmeter, measure resistance between specified TP sensor terminals. See Figure . Replace TP sensor if resistance is not as specified. See TP SENSOR RESISTANCE table. If resistance is as specified, replace PCM. Retest system.