1986 TOYOTA LAND CRUISER start system

- 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

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

DI-108
- DIAGNOSTICSENGINE
301 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)
There is history that the following condi-
tions A and B were met:20 sec. (Continuously)-
A. Vehicle speed40 km/h (25 mph)-
B. Engine speed900 rpm-
Time after engine start120 sec.-
IdleON
Fuel system statusClosed loop
TYPICAL MALFUNCTION THRESHOLDS
Detection CriteriaThreshold
P0130, P0150:
Either of the following conditions A or B is met:3 times or more
A. Front oxygen sensor voltage is 0.55 V or lessFor 18 sec. or more
B. Front oxygen sensor voltage is 0.4 V or moreFor 18 sec. or more
P2195, P2197:
Front heated oxygen sensor voltageConstant 0.55 V or less
P2196, P2198:
Front heated oxygen sensor voltageConstant 0.4 V or more
COMPONENT OPERATING RANGE
ParameterStandard value
In the normal condition, the heated oxygen sensor voltage0 to 1 V
O2S TEST RESULT
Refer to page DI-3 for detailed information.
Front HO2S voltage monitor
If the HO2S voltage is out of the standard value, the ECM interprets this as a malfunction.
TEST IDDescription of TEST DATAConversion FactorUnit
$07Minimum front HO2S voltageN/AV
$08Maximum front HO2S voltageN/AV
WIRING DIAGRAM
Refer to DTC P0031 on page DI-49.

- DIAGNOSTICSENGINE
DI-1 19
312 Author
: Date
:
2004 LAND CRUISER (RM1071U)
MONITOR STRATEGY
RltdDTC
P0133Front heated oxygen sensor response monitor
(Bank 1)
Related DTCs
P0153Front heated oxygen sensor response monitor
(Bank 2)
Main sensors/componentsFront heated oxygen sensor
Required sensors/componentsRelated sensors/componentsCrank position sensor, Vehicle speed sensor,
Mass air flow meter
Frequency of operationOnce per drive cycle
DurationWithin 60 sec.
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)
Frequency idle condition:
There is history that the following condi-
tions were met for 20 sec.A and B
A. Vehicle speed40 km/h (25 mph)-
B. Engine speed900 rpm-
IdleON
Vehicle speed-5 km/h (3 mph)
Fuel system statusClosed loop
Time after engine start120 sec.-
Engine coolant temperature40°C (104°F)-
Frequency cruise condition:
There is history that the following condi-
tions were met for 20 sec.A and B
A. Vehicle speed40 km/h (25 mph)-
B. Engine speed900 rpm-
Intake air amount3 g/sec.13 g/sec.
Time after engine start120 sec.-
IdleOFF
Fuel system statusClosed loop
Engine speed1,000 rpm3,500 rpm
Engine coolant temperature70°C (158°F)-
Slow slope condition:
Both of the following condition were met
for 20 sec.A and B
A. Vehicle speed40 km/h (25 mph)-
B. Engine speed900 rpm-
Time after engine start120 sec.-
IdleON
Vehicle speed-5 km/h (3 mph)

- DIAGNOSTICSENGINE
DI-129
322 Author
: Date
:
2004 LAND CRUISER (RM1071U)
DTC P0134 Oxygen Sensor Circuit No Activity Detected
(Bank 1 Sensor 1)
DTC P0154 Oxygen Sensor Circuit No Activity Detected
(Bank 2 Sensor 1)
CIRCUIT DESCRIPTION
Refer to DTC P0031 on page DI-49.
DTC No.DTC Detecting ConditionTrouble Area
P0134
P0154
After the engine is warmed up, heated oxygen sensor (bank 1,
sensor 1) output does not indicate RICH (more than 0.45 V)
even once when the following conditions continue for 65 sec.
or more:
(a) Engine speed: 1,400 rpm or more
(b) Vehicle speed: 25 to 81 mph (40 to 130 km/h) or more
(c) Throttle valve does not fully closed
(d) 180 sec. or more after starting engine
(e) Engine coolant temperature more than 40°C (104°F)

Open or short in heated oxygen sensor circuit

Heated oxygen sensor

Heated oxygen sensor heater

EFI or ECD relay

Air induction system

Fuel pressure

PCV hose connection

PCV valve and hose

Injector

Gas leakage on exhaust system

PCV piping

ECM
HINT:

Bank 1 refers to bank that includes cylinder No. 1.

Bank 2 refers to bank that does not includes cylinder No. 1.

Sensor 1 refers to the sensor closer to the engine assembly.

After confirming DTC P0134 and P0154, check the output voltage of the heated oxygen sensor in the
"DIAGNOSIS / ENHANCE OBD II / DATA LIST / ALL" using the OBD II scan tool or the hand-held tester.
If output voltage of the heated oxygen sensor is always less than 0.1 V, heated oxygen sensor circuit
may be open or short.
MONITOR DESCRIPTION
The ECM uses the heated oxygen sensor to optimize the air-fuel mixture in closed-loop fuel control. This
control helps decrease exhaust emissions by providing the catalyst with a nearly stoichiometric mixture.
The sensor detects the oxygen level in the exhaust gas and the ECM uses this data to control the air-fuel
ratio. The sensor output voltage ranges from 0 V to 1 V. If the signal voltage is less than 0.4 V, the air-fuel
ratio is LEAN. If the signal voltage is more than 0.55 V, the air-fuel ratio is RICH. If the conditions for the
closed-loop fuel control are met and after a specified time-period, the sensor's output signal never indicates
RICH, the ECM will conclude that the closed-loop fuel control is malfunctioning. The ECM will illuminate the
MIL and a DTC is set.
DIC28-01

A19966
Battery I18
Ignition SW
#8#6 #4 #2
#7 #5ECM
#3 #1
7
5 2 1
4
3 3
1C1 F15
FL BlockEngine Room J/B
1B 6Cowl Side J/B LH
6
E7
E7 E6E5
Y
W G R
IG2
AM2E5 E5 E5 E5
5 I9
Injector No. 1
I16
Injector No. 8 I15
Injector No. 7 I14
Injector No. 6 I13
Injector No. 5 I12
Injector No. 4 I11
Injector No. 3 I10
Injector No. 2
AAJ4
J/C
Ib2 IN2712
AM22E 41
2A 10
9
2B-G
MAIN
B-W R-LL B 12
12 12 12
12 12 12 12
W-R W-R W-R B-R B-R B-R B-RB-R
B-R B-RB-R B-R B-R B-R B-R
B-RB-RB-R B-R B-R
- DIAGNOSTICSENGINE
DI-171
364 Author
: Date
:
2004 LAND CRUISER (RM1071U)
TYPICAL MALFUNCTION THRESHOLDS
Detection CriteriaThreshold
Emission related misfire rate:
1. During the first 1,000 revolutions after engine start
(MIL is set when misfire is detected 1 time)
2. After the first 1,000 revolutions have occurred
(MIL is set when misfire is detected 4 times)
3 %/1,000 revolutions
Catalyst damage misfire count:
1. Low engine rpm area (ex. less than 3,000 rpm):
200 revolutions (MIL is set when misfire is detected 3
times)
2. High engine rpm area: Every 200 revolutions
96 count/200 revolutions
(Threshold varies with engine speed and intake air amount per revolution)
WIRING DIAGRAM
Refer to DTC P0351 on page DI-202 for the wiring diagram of the ignition system.

DI-172
- DIAGNOSTICSENGINE
365 Author
: Date
:
2004 LAND CRUISER (RM1071U)
CONFIRMATION DRIVING PATTERN
(a) Connect the hand-held tester to the DLC3.
(b) Record DTC and the freeze frame data.
(c) Use the hand-held tester to set to the check mode (See page DI-3).
(d) Read the value on the misfire counter for each cylinder when idling. If the value is displayed on the
misfire counter, skip the following procedure of confirmation driving.
(e) Drive the vehicle several times with the engine speed, load and its surrounding range shown with EN-
GINE SPD, CALC LOAD in the freeze frame data or MISFIRE RPM, MISFIRE LOAD in the DATA LIST.
If you have no hand-held tester, turn the ignition switch OFF after the symptom is simulated once. Then re-
peat the simulation process again.
HINT:
In order to memorize the DTC of misfire, it is necessary to drive around MISFIRE RPM, MISFIRE LOAD in
the DATA LIST for the following period of time. Take care not to turn the ignition switch OFF. Turning the
ignition switch OFF switches the diagnosis system from check mode to normal mode. So all DTCs, etc., are
erased.
Engine SpeedTime
Idling3 minutes 30 seconds or more
1,000 rpm3 minutes or more
2,000 rpm1 minute 30 seconds or more
3,000 rpm1 minute or more
(f) Check if there is misfire and DTC and the freeze frame data. Record the DTC's, freeze frame data and
misfire counter data.
(g) Turn the ignition switch OFF and wait at least 5 seconds.
INSPECTION PROCEDURE
HINT:

If DTCs besides misfire DTCs are memorized simultaneously, troubleshoot the non-misfire DTCs first.

If the misfire does not occur when the vehicle is brought to the workshop, the misfire can be confirmed
by reproducing the condition of the freeze frame data. Also, after finishing the repair, confirm that there
is no misfire (See confirmation driving pattern).

On 6 and 8 cylinder engines, misfiring cylinder identification is disabled at high engine speed and only
a general misfire fault code P0300 is stored instead of a cylinder specific misfire fault code (P0301 to
P0308).
If the misfire starts in a high engine speed area or the misfire occurs only in a high engine speed area,
only code P0300 may be stored.
When only a general misfire fault code like P0300 is stored:

Erase the general misfire fault code from the hand-held tester or OBD II scan tool.

Start the engine and drive the confirmation patten.

Read the value of the misfire ratio for each cylinder. Or read the DTC.

Perform repairs on the cylinder that has a high misfire ratio. Or repair the cylinder indicated by the DTC.

After finishing repairs, drive the confirmation pattern again and confirm that no misfire occurs.

When either of SHORT FT #1, LONG FT #1, SHORT FT #2 or LONG FT #2 in the freeze frame data
is over the range of ±20 %, there is a possibility that the air-fuel ratio is becoming RICH (-20 % or
less) or LEAN (+20 % or more).

When COOLANT TEMP in the freeze frame data is less than 80°C (176°F), there is a possibility of
misfire only during engine warm-up.

If the misfire cannot be reproduced, the following reasons may apply: 1) the vehicle has low fuel, 2)
improper fuel is being used, and 3) the ignition plug is contaminated.