1998 TOYOTA LAND CRUISER engine coolant

DI-78
- DIAGNOSTICSENGINE
271 Author
: Date
:
2004 LAND CRUISER (RM1071U)
1 Connect OBD II scan tool or hand-held tester, and read value of engine coolant
temperature.
PREPARATION:
(a) Connect the OBD II scan tool or the hand-held tester to the DLC3.
(b) Turn the ignition switch ON and push the OBD II scan tool or hand-held tester main switch ON.
(c) When using hand-held tester, enter the following menus: DIAGNOSIS / ENHANCED OBD II / DATA
LIST / ALL / COOLANT TEMP.
CHECK:
Read the temperature value on the OBD II scan tool or the hand-held tester.
OK:
Same value as actual engine coolant temperature.
RESULT:
Temperature DisplayedProceed to
-40°C (-40°F)A
140°C (284°F) or moreB
OK (Same as present temperature)C
HINT:

If there is an open circuit, OBD II scan tool or hand-held tester indicates -40°C (-40°F).

If there is a short circuit, OBD II scan tool or hand-held tester indicates 140°C (284°F) or more.
B Go to step 4.
C Check for intermittent problems
(See page DI-3).
A

A19552
Engine Coolant
Temp. Sensor
2
1THW
E2ECM
E2
- DIAGNOSTICSENGINE
DI-79
272 Author
: Date
:
2004 LAND CRUISER (RM1071U)
2 Check for open in harness or ECM.
PREPARATION:
(a) Disconnect the E2 engine coolant temperature (ECT)
sensor connector.
(b) Connect terminals 1 and 2 of the engine coolant tempera-
ture sensor wire harness side connector.
(c) Turn the ignition switch ON.
(d) When using hand-held tester, enter the following menus:
DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL /
COOLANT TEMP.
CHECK:
Read the temperature value on the OBD II scan tool or the
hand-held tester.
OK:
Temperature value: 1405C (2845F) or more
OK Confirm good connection at sensor. If OK, re-
place engine coolant temperature sensor.
NG

A19548
Engine Coolant
Temp. Sensor
ECM
E2 THW
E2 THW
E2
E5
ECM Connector
A19550
Engine Coolant
Temp. Sensor
ECM
2
1
E2 THW E2
DI-80
- DIAGNOSTICSENGINE
273 Author
: Date
:
2004 LAND CRUISER (RM1071U)
3 Check for open in harness or ECM.
PREPARATION:
(a) Disconnect the E2 engine coolant temperature sensor
connector.
(b) Connect terminals THW and E2 of the E5 ECM connector.
HINT:
Before checking, do a visual and contact pressure checks for
the ECM connector.
(c) Turn the ignition switch ON.
(d) When using hand-held tester, enter the following menus:
DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL /
COOLANT TEMP.
CHECK:
Read the temperature value on the OBD II scan tool or the
hand-held tester.
OK:
Temperature value: 1405C (2845F) or more
OK Repair or replace harness or connector.
NG
Confirm good connection at ECM. If OK,
check and replace ECM (See page SF-60).
4 Check for short in harness and ECM.
PREPARATION:
(a) Disconnect the E2 engine coolant temperature sensor
connector.
(b) Turn the ignition switch ON.
(c) When using hand-held tester, enter the following menus:
DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL /
COOLANT TEMP.
CHECK:
Read the temperature value on the OBD II scan tool or the
hand-held tester.
OK:
Temperature value: -405C (-405F)
OK Replace engine coolant temperature sensor.
NG

A19551A19635
ECM Engine Coolant
Temp. Sensor
E2 THW
E5
ECM Connector
- DIAGNOSTICSENGINE
DI-81
274 Author
: Date
:
2004 LAND CRUISER (RM1071U)
5 Check for short in harness or ECM.
PREPARATION:
(a) Disconnect the E5 ECM connector.
(b) Turn the ignition switch ON.
(c) When using hand-held tester, enter the following menus:
DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL /
COOLANT TEMP.
CHECK:
Read the temperature value on the OBD II scan tool or the
hand-held tester.
OK:
Temperature value: -405C (-405F)
OK Repair or replace harness or connector.
NG
Replace ECM (See page SF-60).

DI-82
- DIAGNOSTICSENGINE
275 Author
: Date
:
2004 LAND CRUISER (RM1071U)
DTC P0116 Engine Coolant Temperature Circuit Range/
Performance Problem
CIRCUIT DESCRIPTION
Refer to DTC P0115 on page DI-75.
DTC No.DTC Detecting ConditionTrouble Area
P0116
If the engine coolant temperature was 35°C (95°F) or more but
less than 60°C (140°F) when the engine is started, and if
conditions (a) and (b) are met:
(a) Vehicle has accelerated and decelerated.
(b) Engine coolant temperature remains within 3°C (5.4°F) of
the initial engine coolant temperature (2 trip detection logic)

Engine coolant temperature sensorP0116
If the engine coolant temperature is more than 60°C (140°F)
when the engine is started and the vehicle has accelerated
and decelerated

If the engine coolant temperature sensor records a tempera-
ture variation below 1°C (1.8°F) successively 6 times (6 trip
detection logic)
Engine coolant temperature sensor
MONITOR DESCRIPTION
The ECT (Engine Coolant Temperature) sensor is used to monitor the engine coolant temperature. The ECT
sensor has a thermistor that varies its resistance depending on the temperature of the engine coolant. When
the coolant temperature is low, the resistance in the thermistor increases. When the temperature is high, the
resistance drops. The variations in resistance are reflected in the voltage output from the sensor. The ECM
monitors the sensor voltage and uses this value to calculate the engine coolant temperature. When the sen-
sor output voltage deviates from the normal operating range, the ECM interprets this as a fault in the ECT
sensor and sets a DTC.
Examples:
(1) Upon starting the engine, the ECT is between 35°C (95°F) and 60°C (140°F). If after driving for 250 sec.,
the ECT still remains within 3°C (5.4°F) of the starting temperature, a DTC will be set (2 trip detection logic).
(2) Upon starting the engine, the ECT is over 60°C (140°F). If after driving for 250 sec., the ECT still remains
within 1°C (1.8°F) of the starting temperature, a DTC will be set (6 trip detection logic).
MONITOR STRATEGY
Related DTCsP0116Engine coolant temperature sensor range check
(Stuck)
Main sensors/componentsEngine coolant temperature sensor
Required sensors/componentsRelated sensors/componentsIntake air temperature sensor, Crankshaft
position sensor, Mass air flow meter
Frequency of operationContinuous
Duration250 sec.
MIL operation2 driving cycles (When temperature is fixed between 35C (95F) and 60C (140F))
6 driving cycles (When temperature is fixed at 60C (140F) or more)
Sequence of operationNone
DI1LG-15

- DIAGNOSTICSENGINE
DI-83
276 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 (on page DI-3)
Case 1 (When temperature is fixed between 35C (95F) and 60C (140F)):
Cumulative idle off period250 sec.-
Speed increase 30 km/h (19 mph) or more10 times-
Engine coolant temperature35C (95F)60C (140F)
Intake air temperature-6.7C (20F)-
Case 2 (When temperature is fixed at 60C (140F) or more):
Engine coolant temperature at engine
start60C (140F)-
Intake air temperature-6.7C (20F)-
Stop and goOnce or more (Stop for 20 sec. or more and accelerate to more than 70 km/h (43 mph)
with in 40 sec.)
Steady driving and stop *Once or more
*: Vehicle is driven by 65 km/h (40 mph) or more for 30 sec. or more and the vehicle speed reaches 70 km/h
(44 mph). The vehicle is decelerated from 65 km/h (40 mph) to 3 km/h (2 mph) or less within 35 sec. and
stopped for 10 sec.
TYPICAL MALFUNCTION THRESHOLDS
Detection CriteriaThreshold
Case1 (When temperature is fixed between 35C (95F) and 60C (140F)):
Change of engine coolant temperature valueLess than 3C (5.4F)
Case2 (When temperature is fixed at 60C (140F) or more):
Change of engine coolant temperature value1C (1.8F) or less
COMPONENT OPERATING RANGE
Standard Value
Engine coolant temperature changes with the actual engine coolant temperature.
INSPECTION PROCEDURE
HINT:

If DTC P0115, P0116, P0117, P0118 and P0125 are output simultaneously, ECT sensor circuit may
be open or shorted. 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.
Replace engine coolant temperature sensor.

- 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