| CAUTION | If Engine Control Module (ECM) replacement is instructed in following test, always ensure ECM electrical connectors and ground circuits are okay. If either are defective, repair and repeat testing to confirm ECM malfunction. If ECM is replaced, ECM must be programmed with proper ignition key code for engine immobilizer system. For programming procedures, see COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION, or appropriate ENGINE IMMOBILIZER SYSTEMS article in ACCESSORIES & EQUIPMENT. |
Note. If DTCs P0110, P0115, P0120, P0450 and P1120 are output simultaneously, the E2 sensor ground circuit at terminal No. 18 (Green/White wire) at ECM electrical connector E7 may be open. See WIRING DIAGRAMS article. For ECM electrical connector terminal identification (Схема №4) It may be necessary to check Green/White wire between splice I4 and terminal No. 18 at ECM electrical connector E7. Splice I4 is located behind passenger's side of instrument panel. (Схема №6)
Circuit Description
Throttle Position (TP) sensor uses 2 sensors which detects throttle opening and a malfunction of the TP sensor. TP sensor is located on throttle body and provides an input voltage of 0-5 volts to VTA and VTA2 terminals at ECM in proportion to throttle opening. ECM uses input signals and controls the throttle control motor to provide proper throttle valve opening in response to driving conditions. DTC is set when improper input signals from TP sensor are received at ECM. If DTC P0120 exists, ECM will turn off the power to throttle control motor and throttle valve is closed by the return spring. When this occurs, throttle valve is controlled by throttle cable connected to accelerator pedal. Possible causes are
- TP sensor circuit is open or shorted.
- Defective TP sensor.
- Defective ECM.
Diagnostic Aids
After confirming DTC P0120, use Toyota hand-held tester or scan tool to determine throttle valve opening by reading THROTTLE POS (displayed as a percentage) and THROTTLE POS#2 (displayed as a voltage) to determine probable cause. See THROTTLE VALVE OPENING POSITION SPECIFICATIONS table. Using hand-held tester or scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.
| Condition & Throttle Position Reading | Probable Cause | |
|---|---|---|
| Accelerator Pedal Released | ||
| Throttle Pos (0%) & Throttle Pos #2 (0 Volts) | Open In VC Circuit | |
| Throttle Pos (0%) & Throttle Pos #2 (2.0-2.9 Volts) | Open Or Short To Ground In VTA Circuit | |
| Throttle Pos (8-20%) & Throttle Pos #2 (0 Volts) | Open Or Short To Ground In VTA2 Circuit | |
| Throttle Pos (100%) & Throttle Pos #2 (5 Volts) | Open In E2 Circuit | |
| Accelerator Pedal Depressed | ||
| Throttle Pos (0%) & Throttle Pos #2 (0 Volts) | Open In VC Circuit | |
| Throttle Pos (0%) & Throttle Pos #2 (4.7-5.1 Volts) | Open Or Short To Ground In VTA Circuit | |
| Throttle Pos (64-96%) & Throttle Pos #2 (0 Volts) | Open Or Short To Ground In VTA2 Circuit | |
| Throttle Pos (100%) & Throttle Pos #2 (5 Volts) | Open In E2 Circuit | |
THROTTLE VALVE OPENING POSITION SPECIFICATIONS