DTC P0122/P0123 - Throttle Position (TP) Sensor Circuit Input

P0122 - TP Sensor Circuit Low Input
P0123 - TP Sensor Circuit High Input

Install scan tool. Start engine and check if DTC P0122 or P0123 is present. If DTC is present, go to next step. If DTC is not present, problem is intermittent.
Turn ignition off. Disconnect TP sensor harness connector. Turn ignition on. Connect DVOM between TP sensor harness connector terminal No. 3 and ground. Voltage reading should be 4.8-5.2 volts. If voltage is as specified, go to next step. If voltage is not as specified, check circuit between terminal No. 3 and ECM. See appropriate wiring diagram in WIRING DIAGRAMS section.
Turn ignition off. Connect DVOM between TP sensor harness connector terminal No. 2 and ground. Continuity should be present. If continuity is present, go to next step. If continuity is not present, check circuit between terminal No. 2 and ECM.
Disconnect ECM harness connector. Check for open in circuit between TP sensor harness connector terminal No. 1 and ECM harness connector terminal No. 73. Repair circuit as necessary. If circuit is okay, go to next step.
Reconnect ECM harness connector. Connect DVOM between TP sensor terminals No. 2 and 3. Resistance should be 700-3000 ohms with throttle closed. If resistance is as specified, go to next step. If resistance is not as specified, replace TP sensor.
Connect an analog type ohmmeter between TP sensor terminals No. 1 and 3. Move throttle from idle to wide-open position. Ohmmeter needle should sweep smoothly in proportion to throttle opening. If movement is not smooth, replace TP sensor. If movement is smooth, go to next step.
Reconnect TP sensor harness connector. Clear DTC. See CLEARING DTC(S) . Retest system. If DTC resets, replace ECM.