TOYOTA LAND CRUISER 1998 Factory Repair Manual

- DIAGNOSTICSENGINE
DI-351
544 Author
: Date
:
2004 LAND CRUISER (RM1071U)
4 Check fuel pump (See page SF-7).
NG Repair or replace fuel pump.
OK
5 Check circuit opening relay (See page SF-39).
NG Replace circuit opening relay.
OK
6 Check for open in harness and connector between EFI or ECD relay and fuel
pump, and fuel pump and body ground (See page IN-36).
NG Repair or replace harness or connector.
OK

A19521A19629
FC(+)
ECM ConnectorE9
DI-352
- DIAGNOSTICSENGINE
545 Author
: Date
:
2004 LAND CRUISER (RM1071U)
7 Check voltage between terminal FC and E1 of ECM connector.
PREPARATION:
Turn the ignition switch ON.
CHECK:
Measure the voltage between terminal FC of the ECM connec-
tor and body ground.
OK:
Voltage: 9 to 14 V
NG Check for open in harness and connector be-
tween battery and FC terminal of ECM (See page
IN-36).
OK
Proceed to problem symptoms table
(See page DI-48).
8 Check fuel pump resistor (See page SF-42).
NG Replace fuel pump resistor.
OK
Check for open in harness and connector between circuit opening relay and fuel pump resistor,
and fuel pump resistor and fuel pump (See page IN-36).

- DIAGNOSTICSENGINE
DI-353
546 Author
: Date
:
2004 LAND CRUISER (RM1071U)
OBD II scan tool (excluding hand-held tester):
1 Check operation of fuel pump (See page SF-7).
OK Go to step 7.
NG
2 Check operation of fuel pump relay (See page SF-40).
NG Replace fuel pump relay.
OK
3 Check fuel pump (See page SF-7).
NG Repair or replace fuel pump.
OK
4 Check circuit opening relay (See page SF-39).
NG Replace circuit opening relay.
OK
5 Check for open in harness and connector between EFI or ECD relay and fuel
pump, and fuel pump and body ground (See page IN-36).
NG Repair or replace harness or connector.
OK

A19521A19629
FC(+)
ECM ConnectorE9
DI-354
- DIAGNOSTICSENGINE
547 Author
: Date
:
2004 LAND CRUISER (RM1071U)
6 Check voltage between terminal FC of ECM connector and body ground.
PREPARATION:
Turn the ignition switch ON.
CHECK:
Measure the voltage between terminal FC of the ECM connec-
tor and body ground.
OK:
Voltage: 9 to 14 V
NG Check for open in harness and connector be-
tween battery and FC terminal of ECM (See page
IN-36).
OK
Proceed to problem symptoms table
(See page DI-48).
7 Check fuel pump resistor (See page SF-42).
NG Replace fuel pump resistor.
OK
Check for open in harness and connector between circuit opening relay and fuel pump resistor,
fuel pump resistor and fuel pump (See page IN-36).

A21366
Engine
Room
R/B11ECM
W
E9 11
C13
C12
SB10
Battery7
4I18
Ignition
Switch
73E
3Q 6
B-R
MET
Combination
Meter
Malfunction
Indicator
Lamp AM2IG2 AM2
W
B-RSB
2Q 2D32 78
Cowl Side
J/B RHA
AJ4
J/B W-R
2E 41
10
2A
W-R
1B 9
1C 1
F15 2
Fusible Link
Block B-G
120A MAIN
- DIAGNOSTICSENGINE
DI-355
548 Author
: Date
:
2004 LAND CRUISER (RM1071U)
MIL Circuit
CIRCUIT DESCRIPTION
If the ECM detects a trouble, the MIL lights up. At this time, the ECM records a DTC in the memory.
WIRING DIAGRAM
DIC2V-01

A21033ECM ConnectorW
E9
DI-356
- DIAGNOSTICSENGINE
549 Author
: Date
:
2004 LAND CRUISER (RM1071U)
INSPECTION PROCEDURE
HINT:
Troubleshoot each trouble symptom in accordance with the chart below .
MIL remains onStart inspection from step 1
MIL does not light upStart inspection from step 3
1 Clear DTC.
(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 the OBD II scan tool main switch ON.
(c) Read the DTC (See page DI-3).
(d) Clear the DTC (See page DI-3).
(e) Check that MIL does not light up.
Standard: MIL does not light up
OK Repair circuit indicated by output code
(See page DI-36).
NG
2 Check harness and connector (Check for short in wire harness).
(a) Disconnect the E9 ECM connector.
(b) Turn the ignition switch ON.
(c) Check that MIL does not light up.
Standard: MIL does not light up
OK Replace ECM (See page SF-60).
NG
Check and repair harness and connector be-
tween combination meter and ECM (See page
IN-36).

- DIAGNOSTICSENGINE
DI-357
550 Author
: Date
:
2004 LAND CRUISER (RM1071U)
3 Check that MIL lights up.
Check that MIL lights up when turning the ignition switch ON.
Standard: MIL lights up
OK System OK.
NG
4 Inspect combination meter assy (MIL circuit).
See the combination meter troubleshooting on page BE-63.
NG Repair or replace bulb or combination meter as-
sembly.
OK
Check and repair harness and connector be-
tween combination meter and ECM (See page
IN-36).

DIC22-01
- DIAGNOSTICSENGINE
DI-49
242 Author
: Date
:
CIRCUIT INSPECTION
DTC P0031 Oxygen Sensor Heater Control Circuit Low
(Bank 1 Sensor 1)
DTC P0032 Oxygen Sensor Heater Control Circuit High
(Bank 1 Sensor 1)
DTC P0037 Oxygen Sensor Heater Control Circuit Low
(Bank 1 Sensor 2)
DTC P0038 Oxygen Sensor Heater Control Circuit High
(Bank 1 Sensor 2)
DTC P0051 Oxygen Sensor Heater Control Circuit Low
(Bank 2 Sensor 1)
DTC P0052 Oxygen Sensor Heater Control Circuit High
(Bank 2 Sensor 1)
DTC P0057 Oxygen Sensor Heater Control Circuit Low
(Bank 2 Sensor 2)
DTC P0058 Oxygen Sensor Heater Control Circuit High
(Bank 2 Sensor 2)

P20302
FI7210
A00798
Atmosphere
Housing
Platinum Electrode
Solid Electrolyte
(Zirconia Element)
Platinum Electrode
Heater
Coating (Ceramic)
Exhaust Gas CoverIdeal Air-Fuel Mixture
Output Voltage
Richer - Air Fuel Ratio - Leaner
A21040
Reference(Bank 1 Sensor 1 System Drawing) :
ECM
EFI or ECD Relay
EFI or ECD
Fuse No. 1 From
Battery
GroundOX1A
MREL HT1A
Duty
Control Heater
Sensor Heated Oxygen Sensor
EFI or ECD
Fuse No. 2
E2 DI-50
- DIAGNOSTICSENGINE
243 Author
: Date
:
CIRCUIT DESCRIPTION
To obtain a high purification rate for the CO, HC and NOx components of the exhaust gas, a three-way cata-
lytic converter is used, but for the most efficient use of the three-way catalytic converter, the air-fuel ratio
must be precisely controlled so that it is always close to the stoichiometric air-fuel ratio.
The heated oxygen sensor has the characteristic which its output voltage changes suddenly in the vicinity
of the stoichiometric air-fuel ratio. This characteristic is used to detect the oxygen concentration in the ex-
haust gas and provide the ECM with feedback to control the air-fuel ratio.
When the air-fuel ratio becomes LEAN, the oxygen concentration in the exhaust increases and the heated
oxygen sensor informs the ECM of the LEAN condition (low voltage, i.e. less than 0.45 V).
When the air-fuel ratio is RICHER than the stoichiometric air-fuel ratio, the oxygen concentration in the ex-
haust gas is reduced and the heated oxygen sensor informs the ECM of the RICH condition (high voltage,
i.e. more than 0.45 V). The ECM judges by the voltage output from the heated oxygen sensor whether the
air-fuel ratio is RICH or LEAN and controls the injection time accordingly. However, if malfunction of the
heated oxygen sensor causes output of abnormal voltage, this disables the ECM for performing an accurate
air-fuel ratio control. The heated oxygen sensors include a heater which heats the zirconia element. The
heater is controlled by the ECM. When the intake air volume is low (the temperature of the exhaust gas is
low) current flows to the heater to heat the sensor for accurate oxygen concentration detection.
HINT:
The ECM provides a pulse width modulated control circuit to adjust current through the heater. The heated
oxygen sensor heater circuit uses a relay on the B+ side of the circuit.

- DIAGNOSTICSENGINE
DI-51
244 Author
: Date
:
DTC No.DTC Detecting ConditionTrouble Area
P0031
P0037
Heater current is 0.25 A or less when the heater operates with

Open in heater circuit of heated oxygen sensor

Heated ox
ygen sensor heaterP0037
P0051
P0057
Heater current is 0.25 A or less when the heater o erates with
more than 10.5 V positive battery voltage

Heated oxygen sensor heater

EFI or ECD relay

ECM
P0032
P0038
P0052
P0058
When heater operates, heater current exceeds 2.0 A

Short in heater circuit of heated oxygen sensor

Heated oxygen sensor heater

EFI or ECD relay

ECM
HINT:

Bank 1 refers to bank the 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.

Sensor 2 refers to the sensor farther away from the engine assembly.
MONITOR DESCRIPTION
The sensing portion of the heated oxygen sensor has a zirconia element which is used to detect oxygen
concentration in the exhaust. If the zirconia element is at the proper temperature and difference of the oxy-
gen concentration between the inside and outside surface of sensor is large, the zirconia element will gener-
ate voltage signals. In order to increase the oxygen concentration detecting capacity in the zirconia element,
the ECM supplements the heat from the exhaust with heat from a heating element inside the sensor. When
current in the sensor is out of the standard operating range, the ECM interprets this as a fault in the heated
oxygen sensor and sets a DTC.
Example:
The ECM will set a high current DTC if the current in the sensor is more than 2.0 A when the heater is OFF.
Similarly, the ECM will set a low current DTC if the current is less than 0.25 A when the heater is ON.