Dtc P0121 Throttle / Pedal Position Sensor / Switch A Circuit Range / Performance Problem

Engine. Camry. Acv40 Gsv40
2Gr-Fe Engine Control System. Camry. Acv40 Gsv40

DESCRIPTION

FAIL-SAFE

INSPECTION PROCEDURE

CHECK OTHER DTC OUTPUT (IN ADDITION TO DTC P0121)

DTC P0121 Throttle / Pedal Position Sensor / Switch "A" Circuit Range / Performance Problem


DESCRIPTION

HINT:
  1. This DTC relates to the Throttle Position (TP) sensor.
  2. This ETC (Electrical Throttle Control System) does not use a throttle cable.
The Throttle Position (TP) sensor is mounted on the throttle body, and detects the opening angle of the throttle valve. This sensor is a non-contact type, and uses Hall-effect elements, in order to yield accurate signals, even in extreme driving conditions, such as at high speeds as well as very low speeds.
The TP sensor has two sensor circuits which each transmits a signal, VTA1 and VTA2. VTA1 is used to detect the throttle valve angle and VTA2 is used to detect malfunctions in VTA1. The sensor signal voltages vary between 0 V and 5 V in proportion to the throttle valve opening angle, and are transmitted to the VTA terminals of the ECM.
As the valve closes, the sensor output voltage decreases and as the valve opens, the sensor output voltage increases. The ECM calculates the throttle valve opening angle according to these signals and controls the throttle actuator in response to driver inputs. These signals are also used in calculations such as air-fuel ratio correction, power increase correction and fuel-cut control.

Camry. Acv40 Gsv40.2Gr-Fe Engine Control System.Sfi System. Dtc P0121 Throttle / Pedal Position Sensor / Switch A Circuit Range / Performance Problem


DTC No.
DTC Detection Condition
Trouble Area
P0121
Difference between VTA1 and VTA2 voltages less than 0.8 V, or more than 1.6 V for 2 seconds (1 trip detection logic)
TP sensor (built into throttle body)

FAIL-SAFE

When this DTC, as well as other DTCs relating to ETCS (Electronic Throttle Control System) malfunctions, is set, the ECM enters fail-safe mode. During fail-safe mode, the ECM cuts the current to the throttle actuator off, and the throttle valve is returned to a 6° throttle angle by the return spring. The ECM then adjusts the engine output by controlling the fuel injection (intermittent fuel-cut) and ignition timing, in accordance with the accelerator pedal opening angle, to allow the vehicle to continue at a minimal speed. If the accelerator pedal is fully depressed gently, the vehicle can be driven slowly.
Fail-safe mode continues until a pass condition is detected, and the ignition switch is then turned off.

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. (CAMRY_ACV40 RM000000PDS01FX.html).
1.CHECK OTHER DTC OUTPUT (IN ADDITION TO DTC P0121)

  1. Connect the intelligent tester to the DLC3.

  1. Turn the ignition switch to the ON position.

  1. Turn the tester on.

  1. Enter the following menus: Power train / Engine / DTC.

  1. Read the DTC.

    Result:

    Display (DTC output)
    		Proceed to
    P0121
    		A
    P0121 and other DTCs
    		B


B
GO TO DTC CHART (CAMRY_ACV40 RM000002DSC000X.html)
A

REPLACE THROTTLE BODY (CAMRY_ACV40 RM0000022NL002X.html)