| 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
Accelerator pedal position sensor is located on throttle body and uses 2 sensors which monitor accelerator position. Accelerator pedal position sensor delivers input signals to VPA and VPA2 terminals at ECM in proportion to throttle opening. ECM uses input signals for controlling the throttle control motor. DTC is set when ECM determines voltage is out of range on VPA or VPA2 circuits between accelerator pedal position sensor and ECM. If DTC P1120 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
- Accelerator pedal position sensor circuit is open or shorted.
- Defective accelerator pedal position sensor.
- Defective ECM.
Diagnostic Aids
After confirming DTC P1120, use Toyota hand-held tester or scan tool to confirm throttle valve opening by reading ACCEL POS #1 and ACCEL POS #2 voltages with accelerator pedal released and depressed to determine probable cause for accelerator pedal position sensor. See THROTTLE VALVE OPENING VOLTAGE SPECIFICATIONS table. Using hand-held tester or scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.
| Accelerator Pedal Position & Accelerator Pedal Position Sensor Voltage Reading | Probable Cause | |
|---|---|---|
| Accelerator Pedal Released | ||
| ACCEL POS #1 (0 Volts) & ACCEL POS #2 (0 Volts) | Open In VC Circuit | |
| ACCEL POS #1 (0 Volts) & ACCEL POS #2 (1.8-2.7 Volts) | Open Or Short To Ground In VPA Circuit | |
| ACCEL POS #1 (.3-.9 Volt) & ACCEL POS #2 (0 Volts) | Open Or Short To Ground In VPA2 Circuit | |
| ACCEL POS #1 (5 Volts) & ACCEL POS #2 (5 Volts) | Open In E2 Circuit | |
| Accelerator Pedal Depressed | ||
| ACCEL POS #1 (0 Volts) & ACCEL POS #2 (0 Volts) | Open In VC Circuit | |
| ACCEL POS #1 (0 Volts) & ACCEL POS #2 (4.7-5.1 Volts) | Open Or Short To Ground In VPA Circuit | |
| ACCEL POS #1 (3.2-4.8 Volts) & ACCEL POS #2 (0 Volts) | Open Or Short To Ground In VPA2 Circuit | |
| ACCEL POS #1 (5 Volts) & ACCEL POS #2 (5 Volts) | Open In E2 Circuit | |
THROTTLE VALVE OPENING VOLTAGE SPECIFICATIONS