Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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 | |
NO RELATED
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.