1998 TOYOTA LAND CRUISER sensor

A21022
Throttle Body Connector
VC VTA2VTA
E2
T16
Front View Wire Harness Side:
A21038
E2 (-) VC (+)E5ECM Connector
- DIAGNOSTICSENGINE
DI-95
288 Author
: Date
:
2004 LAND CRUISER (RM1071U)
2 Check voltage between terminals VC and E2 of ECM connector.
PREPARATION:
(a) Disconnect the T16 throttle control motor and sensor con-
nector.
(b) Turn the ignition switch ON.
CHECK:
Measure the voltage between the specified terminals of the E5
ECM connector.
OK:
Tester ConnectionSpecified Condition
VC (E5-18) - E2 (E5-28)4.5 to 5.5 V
NG Replace ECM (See page SF-60).
OK
3 Replace throttle body (See page SF-36).
Go

- DIAGNOSTICSENGINE
DI-97
290 Author
: Date
:
2004 LAND CRUISER (RM1071U)
DTC P0121 Throttle/Pedal Position Sensor/Switch ºAº
Circuit Range/Performance Problem
HINT:
This is the purpose of the ºthrottle position sensorº.
CIRCUIT DESCRIPTION
Refer to DTC P0120 on page DI-84.
DTC No.DTC Detecting ConditionTrouble Area
P0121
Condition (a) continues for 2.0 sec.:
(a) Difference between VTA1 and VTA2 deviates from the
threshold
Throttle control motor and sensor
MONITOR DESCRIPTION
The ECM uses throttle position sensor to monitor the throttle valve opening angle.
This sensor including two 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 confirm prop-
er 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 turn on the MIL and a DTC is
set.
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 (inter-
mittent 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 ºpassº 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.
MONITOR STRATEGY
Related DTCsP0121Throttle position sensor rationality
Required sensors/componentsThrottle position sensor
Frequency of operationContinuous
Duration2 sec.
MIL operationImmediate
Sequence of operationNone
TYPICAL ENABLING CONDITIONS
ItSpecificationItemMinimumMaximum
The monitor will run whenever the follow-
ing DTCs are not presentSee ºList of disable a monitorº (on page DI-3).
VTA2 voltage-4.6 V
DI1LI-19

DI-98
- DIAGNOSTICSENGINE
291 Author
: Date
:
2004 LAND CRUISER (RM1071U)
TYPICAL MALFUNCTION THRESHOLDS
Detection CriteriaThreshold
Different between VTA1 and VTA2
|VTA1 - (VTA2 y 0.8 to 1.2)|*
* Corrected by learning value
Less than 0.1 V and more than 0.4 V
INSPECTION PROCEDURE
HINT:
Read freeze frame data using the hand-held tester or the OBD II scan tool. Freeze frame data records the
engine conditions when a malfunction is detected. When troubleshooting, freeze frame data can help deter-
mine if the vehicle was running or stopped, if the engine was warmed up or not, if the air-fuel ratio was lean
or rich, as well as other data from the time when a malfunction occurred.
Replace throttle control motor and sensor (See page SF-36).

- DIAGNOSTICSENGINE
DI-99
292 Author
: Date
:
2004 LAND CRUISER (RM1071U)
DTC P0125 Insufficient Coolant Temperature
for Closed Loop Fuel Control
CIRCUIT DESCRIPTION
Refer to DTC P0115 on page DI-75.
DTC No.DTC Detection ConditionTrouble Area
If THW or THA is less than -6.6°C (20°F) at engine start
and 20 min. or more after starting engine, engine coolant
temp. sensor value is 20°C (68°F) or less (2 trip detection
logic)
P0125
If THW and THA is between -6.6°C (20°F) and 10°C
(50°F)
at engine start, 5 min. or more after starting engine and
engine coolant temp. sensor value is 20°C (68°F) or less (2
trip detection logic)

Cooling system

Engine coolant temperature sensor

Thermostat
If THW and THA greater than 10°C (50°F) at engine start
and 2 min. or more after starting engine, engine coolant
temp. sensor value is 20°C (68°F) or less (2 trip detection
logic)
MONITOR DESCRIPTION
The ECT (Engine Coolant Temperature) sensor is used to monitor the temperature of the engine coolant.
The resistance of the sensor varies with the actual coolant temperature. The ECM applies a voltage to the
sensor and the varying resistance of the sensor causes the signal voltage to vary. The ECM monitors the
ECT signal voltage after engine start-up.
If, after sufficient time has passed, the sensor still reports that the
engine is not warmed up enough for closed-loop fuel control after sufficient time has passed, the ECM inter-
prets this as a fault in the sensor or cooling system and sets a DTC.
Example:
The engine coolant temperature was 0C (32F) at engine start. After 5 min. running time, the ECT sensor
still indicates that the engine is not warmed up enough to begin air fuel ratio feedback control of the air-fuel
ratio. The ECM interprets this as a fault in the sensor or cooling system and will set a DTC.
MONITOR STRATEGY
Related DTCsP0125Insufficient coolant temperature for closed loop
fuel control
Required sensors/componentsMain sensors/componentsEngine coolant temperature sensor, Cooling sys-
tem, Thermostat
Required sensors/com onents
Related sensors/componentsMass air flow meter
Frequency of operationContinuous
2 min. (at engine start, engine coolant or intake air temperature of 10°C (50°F) or more)
Duration
2 min. (at engine start, engine coolant or intake air tem erature of 10C (50F) or more)
5 min. (at engine start, engine coolant or intake air temperature of -6.6°C (20°F) to 10°C (50°F))Duration5 min. (at engine start, engine coolant or intake air tem erature of 6.6C (20F) to 10C (50F))
20 min. (at engine start, engine coolant or intake air temperature of less than -6.6°C (20°F))
MIL operation2 driving cycles
Sequence of operationNone
DIBSS-02

DI-100
- DIAGNOSTICSENGINE
293 Author
: Date
:
2004 LAND CRUISER (RM1071U)
TYPICAL ENABLING CONDITIONS
ItSpecificationItemMinimumMaximum
The monitor will run whenever the follow-
ing DTCs are not presentSee ºList of Disable a Monitorº table (on page DI-3)
Fuel cutOFF
EngineRunning
TYPICAL MALFUNCTION THRESHOLDS
Detection CriteriaThreshold
Time until ºengine coolant temperatureº detection temperature reaches feedback start temperature
When the temperature at the time of engine starting is
10°C (50°F) or moreEngine coolant temperature is less than ºclosed-loop enable temperatureº
when 2 min. or more after engine start
When the temperature at the time of engine starting is
º-6.6°C (20°F)º to º10°C (50°F)ºEngine coolant temperature is less than ºclosed-loop enable temperatureº
when 5 min. or more after engine start
When the temperature at the time of engine starting is
-6.6°C (20°F) or lessEngine coolant temperature is less than ºclosed-loop enable temperatureº
when 20 min. or more after engine start
INSPECTION PROCEDURE
HINT:

If DTC P0115, P0116, P0117, P0118 and P0125 are output simultaneously, engine coolant tempera-
ture sensor circuit may be open or short. Perform the troubleshooting of DTC P0115, P0117 or P0118
first.

Read freeze frame data using the hand-held tester or the OBD II scan tool. Freeze frame data records
the engine conditions when a malfunction is detected. When troubleshooting, freeze frame data can
help determine if the vehicle was running or stopped, if the engine was warmed up or not, if the air-fuel
ratio was lean or rich, as well as other data from the time when a malfunction occurred.
1 Are there any other codes (besides DTC P0125) being output?
PREPARATION:
(a) Connect the hand-held tester or the OBD II scan tool to the DLC3.
(b) Turn the ignition switch ON and push the hand-held tester or OBD II scan tool main switch ON.
(c) When using hand-held tester, enter the following menus: DIAGNOSIS / ENHANCED OBD II / DTC
INFO / CURRENT CODES.
CHECK:
Read the DTCs using the hand-held tester or the OBD II scan tool.
RESULT:
Display (DTC output)Proceed to
P0125A
ºP0125º and other DTCsB
HINT:
If any other codes besides ºP0125º are output, perform the troubleshooting for those DTCs first.
B Go to relevant DTC chart (See page DI-36).
A

- DIAGNOSTICSENGINE
DI-101
294 Author
: Date
:
2004 LAND CRUISER (RM1071U)
2 Inspect thermostat (See page CO-12).
NG Replace thermostat
(See page CO-1 1).
OK
3 Check cooling system.
CHECK:
Check that there is detect cooling system which causes overcool, such as abnormal radiator fan operation,
modified cooling system and so on.
NG Repair or replace cooling system.
OK
Replace engine coolant temperature sensor.

A20488A21045
Threshold
(75C (167F))Estimated ECT
5 sec.
Indicated coolant temp. reading
DTC set (after 2 driving cycle) ECT
Time DI-102
- DIAGNOSTICSENGINE
295 Author
: Date
:
DTC P0128 Coolant Thermostat (Coolant Temperature
Below Thermostat Regulating Temperature)
HINT:
This is the purpose of ºthermostatº malfunction detection.
CIRCUIT DESCRIPTION
If the engine coolant temperature does not reach 75°C (167°F) despite sufficient warm-up time has
elapsed.
DTC No.DTC Detection conditionTrouble Area
P0128
Condition (a), (b) and (c) are met:
(a) Cold start
(b) After sufficient warm-up time has elapsed
(c) Engine coolant temperature greater than 75°C (167°F)
Thermostat

Cooling system

Engine coolant temperature sensor

ECM
MONITOR DESCRIPTION
The ECM estimates the coolant temperature based on starting temperature, engine loads, and engine
speeds. The ECM then compares the estimated temperature with the actual ECT (Engine Coolant Tempera-
ture). When the estimated coolant temperature reaches 75C (167F), the ECM checks the actual ECT. If
the actual ECT is less than 75C (167F), the ECM will interpret this as a fault in the thermostat or engine
cooling system and set a DTC.
DIC25-01

- DIAGNOSTICSENGINE
DI-103
296 Author
: Date
:
MONITOR STRATEGY
Related DTCsP0128Thermostat
Rid / t
Main sensors/componentsEngine coolant temperature sensor, Engine
cooling system, Thermostat
Required sensors/components
Related sensors/componentsIntake air temperature sensor, Vehicle speed
sensor
Frequency of operationOnce per drive cycle
Duration15 min.
MIL operation2 driving cycles
Sequence of operationNone
TYPICAL ENABLING CONDITIONS
ItSpecificationItemMinimumMaximum
The monitor will run whenever the follow-
ing DTCs are not presentSee ºList of disable a monitorº (on page DI-3)
Battery voltage11.0 V-
Intake air temperature (at engine start)-10C (14F)35C (95F)
Engine coolant temperature
(at engine start)-10C (14F)35C (95F)
Difference between intake air temperature
and engine coolant temperature (at engine
start)
-15C (-27F)7C (12.6F)
TYPICAL MALFUNCTION THRESHOLDS
Detection CriteriaThreshold
Duration period of both A and B5 sec. or more
A Estimated engine coolant temperature75C (167F) or more
B Engine coolant temperature sensor output valueLess than 75C (167F)
MONITOR RESULT
The detailed information is described in CHECKING MONITOR STATUSº (see page DI-3).

TID (Test Identification) is assigned to each emission-related component.

TLT (Test Limit Type):
If TLT is 0, the component is malfunctioning when the test value is higher than the test limit.
If TLT is 1, the component is malfunctioning when the test value is lower than the test limit.

CID (Component Identification) is assigned to each test value.

Unit Conversion is used to calculate the test value indicated on generic OBD scan tools.
TID $08: Thermostat
TLTCIDUnit ConversionDescription of Test ValueDescription of Test Limit
1$01Multiply by 0.625 and sub-
tract 40 (C)ECT sensor output when estimated ECT reaches malfunction criteri-
onMalfunction criterion