Toyota 2GR-FE Manual page 506

ES–350
MONITOR DESCRIPTION
The accelerator pedal position sensor is mounted on the accelerator pedal bracket. The accelerator pedal
position sensor has 2 sensor elements and 2 signal outputs: VPA and VPA2. VPA is used to detect the
actual accelerator pedal angle (used for engine control) and VPA2 is used to detect malfunctions in VPA.
When the difference between the output voltages of VPA and VPA2 deviates from the standard, the ECM
determines that the accelerator pedal position sensor is a malfunctioning. The ECM turns on the MIL and
the DTC is set.
MONITOR STRATEGY
Related DTCs
Required Sensors/Components (Main)
Required Sensors/Components (Sub)
Frequency of Operation
Duration
ES
MIL Operation
Sequence of Operation
TYPICAL ENABLING CONDITIONS
Monitor runs whenever following DTCs are not present
TYPICAL MALFUNCTION THRESHOLDS
Difference between VPA1 voltage (learned value) and VPA2 voltage
(learned value)
FAIL-SAFE
The accelerator pedal position sensor has two (main and sub) sensor circuits. If a malfunction occurs in
either of the sensor circuits, the ECM detects the abnormal signal voltage difference between the two
sensor circuits and switches to limp mode. In limp mode, the functioning circuit is used to calculate the
accelerator pedal opening angle to allow the vehicle to continue driving. If both circuits malfunction, the
ECM regards the opening angle of the accelerator pedal as being fully closed. In this case, the throttle
valve remains closed as if the engine is idling.
If a pass condition is detected and then the ignition switch is turned off, the fail-safe operation stops and
the system returns to a normal condition.
WIRING DIAGRAM
Refer to DTC P2120 (See page ES-338).
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 (See page ES-45).
• This DTC relates to the Accelerator Pedal Position (APP) sensor.
2GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
P2121: Accelerator pedal position (APP) sensor rationality
APP sensor
-
Continuous
0.5 seconds
Immediate
None
None
Less than 0.4 V, or more than 1.2 V