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 connector from TP sensor. Turn ignition on. Using a voltmeter, measure and record voltage between ground and Light Green wire at TP sensor harness connector. Measure and record voltage between ground and Light Green/White wire at TP sensor harness connector. If readings are 4-6 volts, go to next step. If either reading is not as specified, check Light Green wire and/or Light Green/White wire for open or short to ground. Repair as necessary. Retest system.
Using an ohmmeter, measure resistance between specified TP sensor terminals. See TP SENSOR RESISTANCE table. See Figure . Replace TP sensor if resistance is not as specified. If resistance is as specified, check continuity of Light Green/Black wire between TP sensor harness connector and terminal No. 9 on PCM 16-pin harness connector. Repair as needed. If circuit is okay, replace PCM. Retest system.