Page 1209 of 3115
DI-160
- DIAGNOSTICSENGINE
353 Author: Date:
2004 LAND CRUISER (RM1071U)
16 Confirm if vehicle has run out of fuel in past.
NO Check for intermittent problems
(See page DI-3).
YES
DTC P0171, P0172, P0174 or P0175 is caused by running out of fuel.
17 Perform confirmation driving pattern.
HINT:
Clear all DTCs prior to performing the confirmation driving pattern (Refer to step 14).
Go
18 Is there DTC P0171, P0172 P0174 and/or P0175 being output again?
NO Go to step 22.
YES
19 Replace heated oxygen sensor.
Go
20 Perform confirmation driving pattern.
HINT:
Clear all DTCs prior to performing the confirmation driving pattern (Refer to step 14).
Go
Page 1210 of 3115
- DIAGNOSTICSENGINE
DI-161
354 Author: Date:
2004 LAND CRUISER (RM1071U)
21 Is the DTC P0171, P0172, P0174 and/or P0175 being output again?
YES Replace ECM (See page SF-60) and perform
confirmation driving pattern (Refer to step 14).
No
22 Confirm if vehicle has run out of fuel in past.
NO Check for intermittent problems.
(See page DI-3).
YES
DTC is caused by running out of fuel
(DTCs P0171, P0172 P0174 and/or P0175).
Page 1211 of 3115

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
Page 1212 of 3115
- 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
Page 1213 of 3115
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.
Page 1214 of 3115

A19522A19630
E5E7E1
FPR
ECM Connector
A21024
- DIAGNOSTICSENGINE
DI-165
358 Author: Date:
2004 LAND CRUISER (RM1071U)
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.
1 Check voltage between terminal FPR and E1 of ECM.
CHECK:
Measure the voltage between terminals of E5 and E7 ECM con-
nectors.
OK:
Tester ConnectionConditionSpecified Condition
FPR (E5-33) - E1 (E7-1)STA signal ON9 to 14 V
FPR (E5-33) - E1 (E7-1)STA signal OFF0 to 3 V
OK Replace ECM (See page SF-60).
NG
2 Check fuel pump relay.
PREPARATION:
Remove the fuel pump relay from the engine room R/B.
CHECK:
Inspect the fuel pump relay.
OK:
Tester ConnectionSpecified Condition
1 - 2Continuity
3 - 4Continuity
3 - 5 No continuity
3 - 5Continuity
(Apply battery voltage terminal 1 and 2)
NG Replace fuel pump relay.
OK
Page 1215 of 3115
A21342
Engine Room J/B:
Fuel Pump
Relay
A21023
E5
ECM Connector FPR
DI-166
- DIAGNOSTICSENGINE
359 Author: Date:
2004 LAND CRUISER (RM1071U)
3 Check for open and short in harness and connector between fuel pump relay
and ECM.
PREPARATION:
(a) Remove the fuel pump relay from the engine room J/B.
(b) Disconnect the E5 ECM connector.
CHECK:
Measure the resistance between wire harness side connectors.
OK:
Tester ConnectionSpecified Condition
Engine Room J/B (Fuel pump relay ter-
minal 1) - FPR (E5-33)Below 1 W
Engine Room J/B (Fuel pump relay ter-
minal 1) or FPR (E5-33) -
Body ground
10 kW or higher
NG Repair or replace harness or connector.
OK
Replace ECM (See page SF-60).
Page 1216 of 3115

- DIAGNOSTICSENGINE
DI-167
360 Author: Date:
2004 LAND CRUISER (RM1071U)
DTC P0300 Random/Multiple Cylinder Misfire Detected
DTC P0301 Cylinder 1 Misfire Detected
DTC P0302 Cylinder 2 Misfire Detected
DTC P0303 Cylinder 3 Misfire Detected
DTC P0304 Cylinder 4 Misfire Detected
DTC P0305 Cylinder 5 Misfire Detected
DTC P0306 Cylinder 6 Misfire Detected
DTC P0307 Cylinder 7 Misfire Detected
DTC P0308 Cylinder 8 Misfire Detected
CIRCUIT DESCRIPTION
When a misfire occurs in the engine, hydrocarbons (HC) enter the exhaust in high concentrations. If this HC
concentration is high enough, there could be an increase in exhaust emissions levels. High concentrations
of HC can also cause to temperature of the catalyst to increase, possibly damaging the catalyst. To prevent
this increase in emissions and limit the possibility of thermal damage, the ECM monitors the misfire rate.
When the temperature of the catalyst reaches a point of thermal degradation, the ECM will blink the MIL.
For monitoring misfire, the ECM uses both the camshaft position sensor and the crankshaft position sensor.
The camshaft position sensor is used to identify misfiring cylinders and the crankshaft position sensor is used
to measure variations in the crankshaft rotation speed. The misfire counter increments when crankshaft rota-
tion speed variations exceed threshold values.
If the misfiring rate exceeds the threshold value and could cause emissions deterioration, the ECM illumi-
nates the MIL.
DIC2C-01