FI6571
Throttle Position
Sensor
VCC
VTA
IDL
E2
ECM
5V
B+
−
DIAGNOSTICS
ENGINE
DI
−
35
1996 LAND CRUISER (RM451U)
DTC
P0120
Throttle/Pedal Position Sensor/Switch ”A”
Circuit Malfunction
CIRCUIT DESCRIPTION
The throttle position sensor is mounted in the throttle body and
detects the throttle valve opening angle.
When the throttle valve is fully closed, the IDL contacts in the
throttle position sensor are on, so the voltage at the terminal IDL
of the ECM becomes 0 V. At this time, a voltage of approximate-
ly 0.3
−
0.8 V is applied to terminal VTA of the ECM. When the
throttle valve is opened, the IDL contacts go off and thus the
power source voltage of approximately 12 V in the ECM is ap-
plied
to the terminal IDL of the ECM. The voltage applied to the
terminal VTA of the ECM increases in proportion to the opening
angle of the throttle valve and becomes approximately 3.2
−
4.9
V when the throttle valve is fully opened. The ECM judges the
vehicle driving conditions from these signals input from termi-
nals VTA and IDL, and uses them as one of the conditions for
deciding the air
−
fuel ratio correction, power increase correction
and fuel
−
cut control etc.
DTC No.
DTC Detecting Condition
Trouble Area
P0120
Condition (a) or (b) continues
(a) VTA
<
0.1 V, and closed throttle position switch is OFF
(b) VTA
>
4.9 V
S
Open or short in throttle position sensor circuit
S
Throttle position sensor
S
ECM
HINT:
S
If there is open circuit in IDL line, DTC P0120 does not indicate.
S
After confirming DTC P0120 use the OBD II scan tool or TOYOTA hand
−
held tester to confirm the
throttle valve opening percentage and closed throttle position switch condition.
Throttle valve opening position
expressed as percentage
Trouble Area
Throttle valve fully closed
Throttle valve fully open
0 %
0 %
VCC line open
VTA line open or short
Approx. 99 %
Approx. 100 %
E2 line open
DI5P7
−
02
Brought to you by BirfMark
Brought to you by BirfMark
Version 1.00 - 12/21/2010