Page 1105 of 3115

A21543
1
23
4 EFI or ECD Relay
A19522A19630
HT1A HT1BE6
ECM Connector HT2A
HT2B
DI-56
- DIAGNOSTICSENGINE
249 Author: Date:
2 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
3 Check voltage between terminals HT1A, HT2A, HT1B, HT2B of ECM connectors
and body ground.
PREPARATION:
Turn the ignition switch ON.
CHECK:
Measure the voltage between terminals of the ECM connectors
and body ground.
HINT:
Connect terminal HT1A to the bank 1 sensor 1.
Connect terminal HT1B to the bank 1 sensor 2.
Connect terminal HT2A to the bank 2 sensor 1.
Connect terminal HT2B to the bank 2 sensor 2.
OK:
Tester ConnectionSpecified Condition
HT1A (E6-4) - Body ground9 to 14 V
HT1B (E6-5) - Body ground9 to 14 V
HT2A (E6-33) - Body ground9 to 14 V
HT2B (E6-25) - Body ground9 to 14 V
OK Replace ECM (See page SF-60).
NG
Check and repair harness or connector between EFI or ECD relay and heated oxygen sensor, and
heated oxygen sensor and ECM (See page IN-36).
Page 1106 of 3115

FI6929A09074A09707
Power Transistor
Output
Voltage
AB B+
Temperature Sensor
Platinum Hot Wire
Temperature Sensor
Platinum Hot Wire
- DIAGNOSTICSENGINE
DI-57
250 Author: Date:
2004 LAND CRUISER (RM1071U)
DTC P0100 Mass or Volume Air Flow Circuit
DTC P0102 Mass or Volume Air Flow Circuit Low Input
DTC P0103 Mass or Volume Air Flow Circuit High Input
CIRCUIT DESCRIPTION
The Mass Air Flow (MAF) meter measures the amount of air flowing through the throttle valve. The ECM uses
this information to determine the fuel injection time and provide a proper air fuel ratio. Inside the MAF meter,
there is a heated platinum wire exposed to the flow of intake air.
By applying a specific current to the wire, the ECM heats this wire to a given temperature. The flow of incom-
ing air cools the wire and an internal thermistor, affecting their resistance. To maintain a constant current
value, the ECM varies the voltage applied to these components in the MAF meter. The voltage level is pro-
portional to the airflow through the sensor. The ECM interprets this voltage as the intake air amount.
The circuit is constructed so that the platinum hot wire and temperature sensor provide a bridge circuit, with
the power transistor controlled so that the potential of A and B remains equal to maintain the set temperature.
DTC No.DTC Detection ConditionTrouble Area
P0100Open or short in mass air flow meter circuit for more than 3
sec.
P0102Open or short in mass air flow meter circuit for more than 3
sec.Open or short in mass air flow meter circuit
Mass air flow meter
P0103
Open in mass air flow meter circuit for more than 3 sec. (EVG
circuit)
Short in mass air flow meter circuit for more than 3 sec. (+B
circuit)Mass air flow meter
ECM
DIC23-01
Page 1107 of 3115

DI-58
- DIAGNOSTICSENGINE
251 Author: Date:
2004 LAND CRUISER (RM1071U)
HINT:
After confirming DTC P0100, P0102 or P0103, use the hand-held tester or the OBD II scan tool to confirm
the MAF ratio from the ALL menu (to reach the ALL menu: DIAGNOSIS / ENHANCED OBD II / DATA LIST
/ ALL).
Mass Air Flow Value (gm/sec.)Malfunction
Approx. 0.0Mass air flow meter power source circuit open
VG circuit open or short
271.0 or moreEVG circuit open
MONITOR DESCRIPTION
If there is a defect in the MAF (Mass Air Flow) meter or an open or short circuit, the voltage level will deviate
outside the normal operating range. The ECM interprets this deviation as a defect in the MAF meter and sets
a DTC.
Example:
When the MAF meter voltage output is less than 0.2 V, or more than 4.9 V, and if either the condition contin-
ues for more than 3 sec.
MONITOR STRATEGY
P0100Mass air flow meter circuit range check
(Fluttering)
Related DTCsP0102Mass air flow meter circuit range check
(Low voltage)
P0103Mass air flow meter circuit range check
(High voltage)
Required sensors/componentsMass air flow meter
Frequency of operationContinuous
Duration3 sec.
MIL operationImmediate (When engine speed is at less than 4,000 rpm)
2 driving cycles (When engine speed is at 4,000 rpm or more)
Sequence of operationNone
TYPICAL ENABLING CONDITIONS
The monitor will run whenever the follow-
ing DTCs are not presentSee ºList of disable a monitorº (on page DI-3)
The typical enabling condition is not avail-
able-
TYPICAL MALFUNCTION THRESHOLDS
Detection CriteriaThreshold
P0100:
Mass air flow meter voltageLess than 0.2 V or more than 4.9 V
P0102:
Mass air flow meter voltageLess than 0.2 V
P0103:
Mass air flow meter voltageMore than 4.9 V
Page 1108 of 3115
A21361
ECM
MRELVG
E2G
8 E530
E5 29 M1
Mass Air Flow Meter
Battery EFI or ECD No. 2
B-YCowl Side J/B LH
10 5
2A
2BB-YVG
E2G +B
34 5
G-W G-W G-WL-Y
L-Y L-Y
IW3
IW3IN2
IN2
E9 B-W B-WJ/B No. 5
15 2
5D 5C
W-B
Engine Room R/B
EFI or ECD Relay
1
1 1
1
1 2
34Engine Room J/B
4443
1B 1A
1B 1CW-B W-B
B-Y W-B
B-Y
F15
FL Block
MAIN2B-G
EA 1 11EFI or ECD No. 168
2 5
- DIAGNOSTICSENGINE
DI-59
252 Author: Date:
2004 LAND CRUISER (RM1071U)
COMPONENT OPERATING RANGE
ParameterStandard Value
Mass air flow meter voltage0.4 to 2.2 V
WIRING DIAGRAM
Page 1109 of 3115

DI-60
- DIAGNOSTICSENGINE
253 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, and other data from the time the malfunction occurred.
1 Connect OBD II scan tool or hand-held tester, and read value of mass air flow
rate.
PREPARATION:
(a) Connect the OBD II scan tool or hand-held tester to the DLC3.
(b) Turn the ignition switch ON and push the OBD II scan tool or the hand-held tester main switch ON.
(c) Start the engine.
(d) When using hand-held tester, enter the following menus: DIAGNOSIS / ENHANCED OBD II / DATA
LIST / ALL / MAF.
CHECK:
Read the mass air flow rate on the OBD II scan tool or the hand-held tester.
RESULT:
Air Flow Rate (gm/s)Proceed to
0.0A
271.0 or moreB
Between 1 and 270.0 (*1)C
*1: The value must be changed when the throttle valve is opened or closed.
B Go to step 6.
C Check for intermittent problems
(See page DI-3).
A
Page 1110 of 3115
A21226
Wire Harness Side:
+B
Mass Air Flow Meter Connector
M1
A19522A19630
VG E5ECM Connector E2G
- DIAGNOSTICSENGINE
DI-61
254 Author: Date:
2004 LAND CRUISER (RM1071U)
2 Check voltage of mass air flow meter power source.
PREPARATION:
(a) Disconnect the M1 mass air flow meter connector.
(b) Turn the ignition switch ON.
CHECK:
Measure voltage between terminal of the mass air flow meter
connector and body ground.
OK:
Tester ConnectionSpecified Condition
+B (M1-3) - Body ground9 to 14 V
NG Go to step 5.
OK
3 Check voltage between terminal VG of ECM connector and body ground.
PREPARATION:
Start the engine.
CHECK:
Measure the voltage between the specified terminal of the E5
ECM connector.
HINT:
The shift position should be P or N and the A/C switch should
be turned OFF.
OK:
Tester ConnectionConditionSpecified Condition
VG (E5-30) -
E2G (E5-29)Engine is idling0.5 to 3.0 V
OK Replace ECM (See page SF-60).
NG
Page 1111 of 3115
A21226
Wire Harness Side:
Mass Air Flow Meter Connector
M1
E2G VG
A21023
E5
ECM Connector E2G
VG
DI-62
- DIAGNOSTICSENGINE
255 Author: Date:
2004 LAND CRUISER (RM1071U)
4 Check for open and short in harness and connector between mass air flow meter
and ECM.
PREPARATION:
(a) Disconnect the M1 mass air flow meter connector.
(b) Disconnect the E5 ECM connector.
CHECK:
Check the resistance between the wire harness side connec-
tors.
OK:
Tester ConnectionSpecified Condition
VG (M1-5) - VG (E5-30)Below 1 W
E2G (M1-4) - E2G (E5-29)Below 1 W
VG (M1-5) or VG (E5-30) -
Body ground10 kW or higher
NG Repair or replace harness or connector.
OK
Replace mass air flow meter.
Page 1112 of 3115

A20872
Cowl Side J/B LH:
EFI or ECD
No. 2 Fuse
A21226
Wire Harness Side:
Mass Air Flow Meter Connector
M1
+B
A20871
Engine Room J/B:
EFI or ECD
Relay
- DIAGNOSTICSENGINE
DI-63
256 Author: Date:
2004 LAND CRUISER (RM1071U)
5 Check for open and short in harness and connector between mass air flow meter
and EFI or ECD relay.
Check EFI or ECD No. 2 fuse:
PREPARATION:
Remove the EFI or ECD No. 2 fuse from the cowl side J/B LH.
CHECK:
Check for continuity in the EFI or ECD No. 2 fuse.
OK:
Continuity
Check harness and connector:
PREPARATION:
(a) Install the EFI or ECD No. 2 fuse.
(b) Disconnect the M1 mass air flow meter connector.
(c) Remove the EFI or ECD relay from the engine room R/B.
CHECK:
Check the resistance between the wire harness side connec-
tors.
OK:
Tester ConnectionSpecified Condition
+B (M1-3) - Engine Room J/B (EFI or
ECD relay terminal 1)Below 1 W
+B (M1-3) or Engine room J/B (EFI or
ECD relay terminal 1) -
Body ground
10 kW or higher
NG Repair or replace harness or connector.
OK
Check ECM power source circuit
(See page DI-345).