DTC P0120 - THROTTLE POSITION (TP) CIRCUIT MALFUNCTION Mitsubishi Eclipse II

Note. For component terminal identification, see TERMINAL IDENTIFICATION in this article. For wiring diagrams, see WIRING DIAGRAMS - 2.0L TURBO article.

1. Using scan tool in MUT II mode, read SERVICE DATA No. 26 (closed throttle position switch). Scan tool display should switch between ON (throttle at idle) and OFF (throttle open slightly). If display is as specified, go to step 3). If display is not as specified, go to next step.
2. Disconnect TP sensor connector. Check continuity between TP sensor terminals No. 3 (Yellow/Red wire) and No. 4 (Black wire). Continuity should exist with throttle at idle. Continuity should not exist when throttle is opened. If continuity is as specified, go to next step. If continuity is not as specified, replace TP sensor.
3. Disconnect TP sensor connector. Check resistance between ground and TP sensor connector terminals No. 1 (Green/Yellow wire) and No. 4 (Black wire). Resistance should be 3.5-6.5 k/ohms. Go to next step.
4. Check resistance between ground and TP sensor connector terminals No. 2 (Brown/Red wire) and No. 4 (Black wire). Slowly open and close throttle. If resistance is not as specified or does not change smoothly in proportion to throttle opening, replace TP sensor. If resistance is as specified, go to next step.
5. Turn ignition on. Check voltage between ground and TP sensor connector terminal No. 1 (Green/Yellow). Voltage should be 4.8-5.2 volts. Check continuity between ground and TP sensor connector terminal No. 4 (Black wire). If voltage is as specified and continuity exists, go to next step. If voltage is not as specified or continuity does not exist, go to step 8).
6. Connect TP sensor connector. Turn ignition on. With PCM connector connected, check voltage between ground and PCM connector terminal No. 84 (Brown/Red wire). Voltage should be 0.3-1.0 volt with throttle at idle and 4.5-5.5 volts with throttle full open. Go to next step.
7. If voltage is not as specified, check TP sensor connector and wiring harness between PCM and TP sensor connector. If voltage is as specified, check PCM connector. If PCM connector is okay, replace PCM.
8. Check PCM connector and wiring harness between PCM and TP sensor connector. If connector and wiring are okay, replace PCM.