1998 TOYOTA LAND CRUISER relay

A21543
1
23
4 EFI or ECD Relay
A21341
+B
OX
E1HT
H6
H8
Components Side:
Bank1 Sensor2, Bank2 Sensor2
A21340
OX2B
HT1BE6
ECM ConnectorOX1B
HT2B
- DIAGNOSTICSENGINE
DI-145
338 Author
: Date
:
2004 LAND CRUISER (RM1071U)
4 Check EFI or ECD relay.
PREPARATION:
Remove the EFI or ECD relay from the engine room R/B.
CHECK:
Inspect the EFI or ECD relay.
OK:
Terminal No.ConditionSpecified Condition
2 - 4ConstantContinuity
UsuallyNo Continuity
1 - 3Apply B+ between
terminals 2 and 4Continuity
NG Replace EFI or ECD relay.
OK
5 Check for open and short in harness and connector between ECM and heated
oxygen sensor.
PREPARATION:
(a) Disconnect the H6 or H8 heated oxygen sensor connec-
tor.
(b) Disconnect the E6 ECM connector.
CHECK:
Measure the resistance between the wire harness side connec-
tors.
OK:
Tester ConnectionSpecified Condition
OX (H6-3) - OX1B (E6-29)Below 1 W
HT (H6-1) - HT1B (E6-5)Below 1 W
OX (H8-3) - OX2B (E6-21)Below 1 W
HT (H8-1) - HT2B (E6-25)Below 1 W
OX (H6-3) or OX1B (E6-29) -
Body ground10 kW or higher
HT (H6-1) or HT1B (E6-5) -
Body ground10 kW or higher
OX (H8-3) or OX2B (E6-21) -
Body ground10 kW or higher
HT (H8-1) or HT2B (E6-25) -
Body ground10 kW or higher

A21040
Reference (Bank 1 Sensor 1 System Drawing)
From
BatteryEFI or ECD
No. 1 FuseEFI or ECD
RelayEFI or ECD
No. 2 FuseHeater Oxygen
Sensor
Heater
SensorHT1A
OX1A
E2
MRELECM
DI-146
- DIAGNOSTICSENGINE
339 Author
: Date
:
2004 LAND CRUISER (RM1071U)
NG Repair or replace harness or connector.
OK
Replace heated oxygen sensor.
6 Perform confirmation driving pattern.
HINT:
Clear all DTCs prior to performing the confirmation driving pattern.
Go
7 Is the DTC P0136 or P0156 being output again?
NO Check for intermittent problems.
YES
Replace heated oxygen sensor.

- DIAGNOSTICSENGINE
DI-147
340 Author
: Date
:
2004 LAND CRUISER (RM1071U)
DTC P0171 System too Lean (Bank 1)
DTC P0172 System too Rich (Bank 1)
DTC P0174 System too Lean (Bank 2)
DTC P0175 System too Rich (Bank 2)
CIRCUIT DESCRIPTION
The fuel trim is related to the feedback compensation value, not to the basic injection time. The fuel trim in-
cludes the short-term fuel trim and the long-term fuel trim.
The short-term fuel trim is the short-term fuel compensation used to maintain the air-fuel ratio at stoichio-
metric air-fuel ratio. The signal from the heated oxygen sensor indicates whether the air-fuel ratio is RICH
or LEAN compared to the stoichiometric air-fuel ratio. This variance triggers a reduction in the fuel volume
if the air-fuel ratio is RICH, and an increase in the fuel volume if it is LEAN.
The long-term fuel trim is the overall fuel compensation carried out in long-term to compensate for a continu-
al deviation of the short-term fuel trim from the central value, due to individual engine differences, wear over-
time and changes in the operating environment.
If both the short-term fuel trim and the long-term fuel trim are LEAN or RICH beyond a certain value, it is
detected as a malfunction and the MIL is illuminated and a DTC is set.
DTC No.DTC Detecting ConditionTrouble Area
P0171
P0174When air-fuel ratio feedback is stable after warming up engine,
fuel trim is considerably in error on LEAN side
(2 trip detection logic)
Air induction system
Injector blockage
Mass air flow meter
Engine coolant temperature sensor
Fuel pressure
Gas leakage in exhaust system
Open or short in heated oxygen sensor (bank 1, 2 sensor 1)
circuit
Heated oxygen sensor (bank 1, 2 sensor 1)
Heated oxygen sensor heater (bank 1, 2 sensor 1)
EFI or ECD relay
PCV piping
ECM
P0172
P0175When air-fuel ratio feedback is stable after warming up engine,
fuel trim is considerably in error on RICH side
(2 trip detection logic)
Injector leak, blockage
Mass air flow meter
Engine coolant temperature sensor
Ignition system
Fuel pressure
Gas leakage in exhaust system
Open or short in heated oxygen sensor (bank 1, 2 sensor 1)
circuit
Heated oxygen sensor (bank 1, 2 sensor 1)
ECM
DIC2A-01

A20870
E1 +B
OX
+BHT
OX E1HT H5
H7
H6
H8
Components Side:
Bank1 Sensor1, Bank2 Sensor1
Bank1 Sensor2, Bank2 Sensor2
A21543
1
23
4 EFI or ECD Relay
DI-156
- DIAGNOSTICSENGINE
349 Author
: Date
:
2004 LAND CRUISER (RM1071U)
10 Check resistance of heated oxygen sensor heater.
PREPARATION:
Disconnect the H5, H6, H7 or H8 heated oxygen sensor con-
nector.
CHECK:
Measure resistance between terminals of the heated oxygen
sensor.
OK:
Tester ConnectionSpecified Condition
HT (H5-1) - +B (H5-2)11 to 16 W (20°C)
HT (H6-1) - +B (H6-2)11 to 16 W (20°C)
HT (H7-1) - +B (H7-2)11 to 16 W (20°C)
HT (H8-1) - +B (H8-2)11 to 16 W (20°C)
NG Replace heated oxygen sensor.
OK
11 Check EFI or ECD relay.
PREPARATION:
Remove the EFI or ECD relay from the engine room R/B.
CHECK:
Inspect the EFI or ECD relay.
OK:
Terminal No.ConditionSpecified Condition
2 - 4ConstantContinuity
UsuallyNo Continuity
1 - 3Apply B+ between
terminals 2 and 4Continuity
NG Replace EFI or ECD relay.
OK

A21040
Reference (Bank 1 Sensor 1 System Drawing)
From
BatteryEFI or ECD
No. 1 FuseEFI or ECD
RelayEFI or ECD
No. 2 FuseHeater Oxygen
Sensor
Heater
SensorHT1A
OX1A
E2
MRELECM
DI-158
- DIAGNOSTICSENGINE
351 Author
: Date
:
2004 LAND CRUISER (RM1071U)
NG Replace or replace harness or connector.
OK
13 Replace heated oxygen sensor.
Go

A21043
Starter Relay EFI Relay
Circuit Opening
Relay
Fuel Pump RelayMREL
FPRTr2
Tr1 EFI
IGNECM
FC
NE Fuel Pump
Battery
StarterFuel Pump Resistor
AM2Ignition Switch
STA
Crankshaft Position
Sensor (NE Signal) DI-162
- DIAGNOSTICSENGINE
355 Author
: Date
:
2004 LAND CRUISER (RM1071U)
DTC P0230 Fuel Pump Primary Circuit
CIRCUIT DESCRIPTION
In the diagram below, when the engine is cranked, current flows from terminal STAR of the ECM to the starter
relay coil and also current flows to terminal STA of the ECM (STA signal).
When the STA signal and NE signal are input to the ECM, the Tr1 is turned ON, current flows to the coil of
the circuit opening relay, the relay switches on, power is supplied to the fuel pump, and the fuel pump oper-
ates.
While the NE signal is generated (engine running), the ECM keeps the Tr1 ON (circuit opening relay ON)
and the fuel pump also keeps operating.
The fuel pump speed is controlled at two levels (high speed or low speed) by the condition of the engine
(starting, light load, heavy load). When the engine starts (STA ON), the Tr2 in the ECM is OFF, so the fuel
pump relay closes and battery positive voltage is applied directly to the fuel pump. The fuel pump operates
at high speed.
After the engine starts during idling or light loads, since the Tr2 goes ON, power is supplied to the fuel pump
via the fuel pump resistor. The fuel pump operates at low speed.
DIC2B-01

- DIAGNOSTICSENGINE
DI-163
356 Author
: Date
:
2004 LAND CRUISER (RM1071U)DTC No.
DTC Detecting ConditionTrouble Area
P0230Open or short in fuel pump relay circuit

Open or short in fuel pump relay circuit

Fuel pump relay

Circuit opening relay

Fuel pump

ECM

A19965A20085
ECM
FPR
FC
MREL Engine Room R/B
Engine Room J/B
Cowl Side J/B RH Cowl Side J/B LH
I18
Ignition SW
Cowl Side J/B LHJ/B No. 5
J4
J/C
MAINJ/B No. 6
F15
FL Block Fuel Pump
Relay
C/OPN Relay
EFI or ECD Relay
EFI or ECD No. 1
AM2
IGN
Battery 1
1
1
1
1
111 1 1 1 1 1
1 2 35 4
3
125
1
2 3
4 R-L
R-L
R-LB
BB
IA29
BB1
2
G-W6D
6C710
G-W
B-Y
B-Y
W-BG-W
B-W
B-WF12
Fuel
Pump
1
4
2 16
13
155C 5D
5C 5D
5C 5D B-R
B-Y
B-W
B-YM4
5 B
W-B33
E5
10
8 E9
E9
BB1 8
W-B 1A
1B
1B
1B 1C1 9 11 44 43
422
3E3B
AA B-R
B-RB-R
6 7
2K 2A 2E W-R W-R
B-G
W-B
33
IF EAB-W
B-W
F14 Fuel Pump
Resistor
L-B
4110
2 IG2 AM2If113
G-WG-W 12
DI-164
- DIAGNOSTICSENGINE
357 Author
: Date
:
2004 LAND CRUISER (RM1071U)
WIRING DIAGRAM
HINT:
This diagnostic chart is based on premise that engine is started. If the engine is not started, proceed to prob-
lem symptoms table on DI-48.