Diagnostic Aids
WARNING: This page is about a different car, the 2002 Toyota Tundra. However, it is still accessible from the selected car via links, so may be relevant.
After confirming DTC P0120, use Toyota hand-held tester or scan tool to read 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.
THROTTLE VALVE OPENING POSITION SPECIFICATIONS
| 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 | |