Brand:
Toyota
Model Name:
4Runner GRN210 215 UZN210 215
Manual:
Repair Manual
Section:
2Uz-Fe Engine Control System
Title:
Sfi System
DTC P0121 Throttle / Pedal Position Sensor / Switch "A" Circuit Range / Performance Problem
- HINT:
- This is the purpose of the throttle position sensor.
DESCRIPTION
Refer to DTC P0120 (Click here).| DTC No. | DTC Detection Condition | Trouble Area |
| P0121 | Difference between voltage output of VTA1 and VTA2 deviates from the threshold for 2.0 seconds. | Throttle Position (TP) sensor (built into throttle body) |
MONITOR DESCRIPTION
The ECM uses the throttle position sensor to monitor the throttle valve opening angle.This sensor includes 2 signals: VTA1 and VTA2. VTA1 is used to detect the throttle opening angle and VTA2 is used to detect malfunctions in VTA1. There are several checks that the ECM performs to confirm proper operation of the throttle position sensor and VTA1.
There is a specific voltage difference expected between VTA1 and VTA2 for each throttle opening angle.
If the voltage output difference of the VTA1 and VTA2 deviates from the normal operating range, the ECM interprets this as a malfunction of the throttle position sensor. The ECM will illuminate the MIL and set a DTC. This monitor runs for 2 seconds (the first 2 seconds of engine idle) after the engine is started (1 trip detection logic).
MONITOR STRATEGY
| Related DTCs | P0121: Throttle Position (TP) sensor rationality |
| Required Sensors/Components (Main) | TP sensor |
| Required Sensors/Components (Related) | - |
| Frequency of Operation | Continuous |
| Duration | Within 2 seconds |
| MIL Operation | Immediate |
| Sequence of Operation | None |
TYPICAL ENABLING CONDITIONS
| The monitor will run whenever this DTC is not present | None |
| Either of following conditions is set | Condition A or B |
| A. Ignition switch | ON |
| B. Electric throttle motor power | ON |
| TP sensor malfunction (P0120, P0122, P0123, P0220, P0222, P0223, P2135) | Not detected |
TYPICAL MALFUNCTION THRESHOLDS
| Different between VTA1 and VTA2 [VTA1 - (VTA2 x 0.8 to 1.2)]* * Corrected by learning value | Less than 0.8 V and more than 1.6 V |
FAIL-SAFE
If the ETCS (Electronic Throttle Control System) has a malfunction, the ECM cuts off current to the throttle control motor. The throttle control valve returns to a predetermined opening angle (approximately 16°) by the force of the return spring. The ECM then adjusts the engine output by controlling the fuel infection (intermittent fuel-cut) and ignition timing in accordance with the accelerator pedal opening angle to enable the vehicle to continue at a minimum speed.If the accelerator pedal is depressed firmly and slowly, the vehicle can be driven slowly.
If a "pass" condition is detected and then the ignition switch is turned OFF, the fail-safe operation will stop and the system will return to normal condition.
WIRING DIAGRAM
Refer to DTC P0120 (Click here).INSPECTION PROCEDURE
- HINT:
- Read freeze frame data using the intelligent tester. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air/fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.
- This is the repair procedure of the throttle position sensor.
1.READ OTHER DTC OUTPUT (IN ADDITION TO DTC P0121)
Connect the intelligent tester to the DLC3 with CAN VIM.
Turn the ignition switch ON.
Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.
Read the DTCs.
- Result:
Display (DTC Output) Proceed to P0121 A P0121 and other DTCs B
- HINT:
- If any other codes besides P0121 are output, perform the troubleshooting for those codes first.
| GO TO RELEVANT DTC CHART | |||
| A | |
 | |
| REPLACE THROTTLE BODY | |