DI−12
−
DIAGNOSTICS ENGINE
1996 LAND CRUISER (RM451U)
(b) TOYOTA Enhanced Signals.
TOYOTA hand−held tester displayMeasurement ItemNormal Condition*
MISFIRE RPMEngine RPM for first misfire rangeMisfire 0: 0 rpm
MISFIRE LOADEngine load for first misfire rangeMisfire 0: 0 g/r
INJECTORFuel injection time for cylinder No.1Idling: 2.0 − 3.5 ms
IAC STEP POSIntake Air Control Valve step position
Opening position step motor type IAC valveIdling: 10 − 50 step
STARTER SIGStarter SignalCranking: ON
CTP SWClosed Throttle Position Switch SignalThrottle Fully Closed: ON
A/C SIGA/C Switch SignalA/C ON: ON
PNP SWPark/Neutral Position Switch SignalP or N Position: ON
STOP LIGHT SWStop Light Switch SignalStop light switch ON: ON
FC IDLFuel Cut Idle: Fuel cut when throttle valve fully
closed, during decelerationFuel cut operating: ON
FC TAUFuel Cut TAU: Fuel cut during very light loadFuel cut operating: ON
CYL#1 − CYL#6Ratio of revolution variation for each cylinder
when variation is large0%
IGNITIONIgnition rate for all cylinders every 1,000 revolu-
tions0 − 3,000 rpm
EGRT GASEGR Gas Temp. Sensor V alueEGR not operating: Temp. between intake air
temp. and engine coolant temp.
EGR SYSTEMEGR System Operating ConditionIdling: OFF
FUEL PRES UP VSVFuel Pressure Up VSV SignalHigh temp. restarting: ON
FUEL PUMPFuel Pump SignalIdling: ON
TOTAL FT B1Total Fuel Trim Bank 1: Average value for fuel
trim system of bank 1Idling: 0.8 − 1.2 V
O2 LR B1, S1
Oxygen Sensor Lean Rich Bank 1, Sensor 1
Response time for oxygen sensor output to
switch from lean to rich
Idling after warmed up: 0 − 1,000 msec.
O2 RL B1, S1
Oxygen Sensor Rich Lean Bank 1, Sensor 1
Response time for oxygen sensor output to
switch from rich to lean
Idling after warmed up: 0 − 1,000 msec.
∗: If no conditions are specifically stated for ”ldling”, it means t\
he shift lever is at N or P position, the A/C switch
is OFF and all accessory switches are OFF.
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FI6571
Throttle Position
SensorVCCVTA
IDLE2 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 ConditionTrouble Area
P0120
Condition (a) or (b) continues
(a) VTA < 0.1 V, and closed throttle position switch is OFF
(b) VTA > 4.9 VOpen or short in throttle position sensor circuit
Throttle position sensor
ECM
HINT:
If there is open circuit in IDL line, DTC P0120 does not indicate.
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 closedThrottle valve fully open
0 %0 %VCC line open
VTA line open or short
Approx. 99 %Approx. 100 %E2 line open
DI5P7−02
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