mass air flow TOYOTA HIGHLANDER 2001 Service Repair Manual

2005 HIGHLANDER (EWD592U)
76
Engine Control for 3MZ-FE
14 BJ1 I 9
2
18 BJ1 IM1
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E 3E2E1E 16
B
Y
L
NSW
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B- R
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STA
B
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12
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V
7. 5A
STARTER
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1E 1
2 1
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B- R B- R
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B- R B- R L- WR B- R
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16 5Y VTA1 VC THW
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YV 2S15
M 1
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W- B
W- B
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C 8
FAN NO. 1 Relay
CF E 34 E 15 B 19
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M-
B- R
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R- Y
15
IO1
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ETCS
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B- R L B- R P 1
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(
*1)
IM1 14
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BJ117
BR Fr om Power Source System (
See Page 62)
FAN NO. 2 Relay
E 5(
A)
, E 6(
B)
, E 7(
E)
, E 8(
D)
, E 9(
C)
S28(
A)
, S29(
B)
Engine Control Module
Mass Air Flow
Meter
Park/Neutral
Position SW
Stop Light SW
Short Connector
Throttle Control Motor
VSV (
ACIS No. 2)
VSV
(
Canister Closed Valve) VSV (
EVAP) V 4 Engine Coolant Temp.
Sensor E 2
VG E2G THA
+B E2
Throttle Position Sensor

2005 HIGHLANDER (EWD592U)
82
Engine Control for 3MZ-FE
The engine control system utilizes a microcomputer and maintains overall control of the engine, transmission etc. An outline
of the engine control is given here.
1. Input Signals
(1) Engine coolant temp. signal circuit
The engine coolant temp. sensor detects the engine coolant temp. and has a built-in thermistor with a resistance, which
varies according to the engine coolant temp. The engine coolant temp. which is input into TERMINAL THW of the
engine control module as a control signal.
(2) Intake air temp. signal circuit
The intake air temp. sensor is installed in the mass air flow meter and detects the intake air temp. which is input as a
control signal to TERMINAL THA of the engine control module.
(3) Vehicle speed signal circuit
The vehicle speed signal is input from the ABS speed sensor to skid control ECU with actuator, and are sent to the
engine control module through communication control.
(4) RPM signal circuit
Camshaft position is detected by the VVT sensors and its signal is input to TERMINALS VV1+ and VV2+ of the engine
control module as a control signal. Also, engine RPM is detected by the crankshaft position sensor and is input as a
control signal to TERMINAL NE+.
(5) Throttle position signal circuit
The throttle control motor and sensor detects the throttle valve opening angle as a control signal, which is input into
TERMINALS VTA1 and VTA2 of the engine control module.
(6) Battery signal circuit
Voltage is constantly applied to TERMINAL BATT of the engine control module. With the ignition SW turned on, the
voltage for engine control module start-up power supply is applied to TERMINALS +B and +B2 of the engine control
module via the EFI relay.
The current flowing through the IGN fuse flows to TERMINAL IGSW of the engine control module.
(7) Intake air volume signal circuit
Intake air volume is detected by the mass air flow meter and the signal is input to TERMINAL VG of the engine control
module as a control signal.
(8) Stop light SW signal circuit
The stop light SW is used to detect whether the vehicle is braking or not and the signal is input into TERMINAL STP of
the engine control module as a control signal.
(9) Starter signal circuit
To confirm whether the engine is cranking, the voltage is applied to the starter motor during cranking is detected and the
signal is input into TERMINAL STA of the engine control module as a control signal.
(10) Engine knock signal circuit
Engine knocking is detected by knock sensors and the signal is input into TERMINALS KNK1 and KNK2 as a control
signal.
(11) Air fuel ration signal circuit
The air fuel ration is detected and input as a control signal into TERMINALS A1A+ and A2A+ of the engine control
module.
(12) Oxygen sensor signal circuit
The oxygen density in the exhaust gases is detected and input as a control signal into TERMINALS OX1B and OX2B of
the engine control module.
To maintain stable detection performance by the heated oxygen sensor, a heater is used for warning the sensor. The
heater is also controlled by the engine control module (HT1B and HT2B).
(13) Fuel cut in a collision
The system receives the collision signal from airbag sensor assembly in the vehicle has a collision and stops the fuel
pump operation on the side of the engine control module.
System Outline

2005 HIGHLANDER (EWD592U)
89
(
Shielded)
A 8
WM-
WA 10 A 3 A 2 A 1M+
B
Y
Y BRW
W
D 5D23 D31
3 1E 9 BR
4 2
Y B- W
BR B- R
B- R
B- RGR MREL
A1A- A1A+ HA1A FC BATT +B +B2
A 9
P
IGSW
A 6
B- R
B- R
Y GR
BR
T13
E2 P- L
BR
P5A
BRG
5 1
VG THA EVG
R L- B L- W
3
17 C
#1
E 4
(
Shielded)
GE01 M+
B
34 E
2
12
28 E 19 E18 E 31 E C 3 E 9
1
2BR
5 43
M 1
2C1
W
M- VTA1 E 9
G B- R
B- W
B- R
Y Y
5B
G- B BR
BR
6
E 21
B- RVTA2 VC THW E2E 2
PRG
1
L
EI 6
#2
2
B
E2VC
#3
3E 29 E20
4
W
BR
VTA2
Y
VTA1
E 30
E #4
I 7
V 4
P (
Shielded) B
Y
L
P
G
5A 12ELS2
EXCDIA1 7
E 9
GR * 1 : w/ Rear Seat Entertainment System
IM15
G
(
*1)(
*1)
IK3 13S28(
A)
, S29(
B)
E 5(
A)
, E 6(
B)
, E 7(
E)
, E 8(
D)
, E 9(
C)
Air Fuel Ratio Sensor
(
Bank 1 Sensor 1)Engine Coolant Temp. Sensor
Engine Control Module
Mass Air Flow Meter
Short Connector
Throttle Control Motor
VSV (
EVAP)
Voltage Inverter V15
+B E2
E2G THA VG
HT AF+
+B AF- Throttle Position Sensor

2005 HIGHLANDER (EWD592U)
95
The engine control system utilizes a microcomputer and maintains overall control of the engine, transmission etc. An outline
of the engine control is given here.
1. Input Signals
(1) Engine coolant temp. signal circuit
The engine coolant temp. sensor detects the engine coolant temp. and has a built-in thermistor with a resistance, which
varies according to the engine coolant temp.. The engine coolant temp. which is input into TERMINAL THW of the
engine control module as a control signal.
(2) Intake air temp. signal circuit
The intake air temp. sensor is installed in the mass air flow meter and detects the intake air temp. which is input as a
control signal to TERMINAL THA of the engine control module.
(3) Vehicle speed signal circuit
The vehicle speed signal is input from the ABS speed sensor to skid control ECU with actuator, and are sent to the
engine control module through communication control.
(4) RPM signal circuit
Camshaft position and crankshaft position are detected by the camshaft position sensor and crankshaft position sensor.
Camshaft position is input as a control signal to TERMINAL G2+ of the engine control module, and engine RPM is input
into TERMINAL NE+.
(5) Throttle position signal circuit
The throttle position sensor detects the throttle valve opening angle as a control signal, which is input into TERMINALS
VTA1 and VTA2 of the engine control module.
(6) Battery signal circuit
Voltage is constantly applied to TERMINAL BATT of the engine control module. With the ignition SW turned on, the
voltage for engine control module start-up power supply is applied to TERMINALS +B and +B2 of the engine control
module via the EFI relay.
The current flowing through the IGN fuse flows to TERMINAL IGSW of the engine control module.
(7) Intake air volume signal circuit
Intake air volume is detected by the mass air flow meter and the signal is input to TERMINAL VG of the engine control
module as a control signal.
(8) Stop light SW signal circuit
The stop light SW is used to detect whether the vehicle is braking or not and the signal is input into TERMINAL STP of
the engine control module as a control signal.
(9) Starter signal circuit
To confirm whether the engine is cranking, the voltage is applied to the starter motor during cranking is detected and the
signal is input into TERMINAL STA of the engine control module as a control signal.
(10) Engine knock signal circuit
Engine knocking is detected by knock sensor and the signal is input into TERMINAL KNK1 as a control signal.
(11) Air fuel ratio signal system
The air fuel ratio is detected and input as a control signal into TERMINAL A1A+ of the engine control module.
(12) Oxygen sensor signal circuit
The oxygen density in the exhaust gases is detected and input as a control signal into TERMINAL OX1B of the engine
control module. To maintain stable detection performance by the heated oxygen sensor, a heater is used for warning the
sensor. The heater is also controlled by engine control module (O1B-).
(13) Fuel cut in a collision
The system receives the collision signal from center airbag sensor assembly in the vehicle has a collision and stops the
fuel pump operation on the side of the engine control module.
System Outline

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- DIAGNOSTICSSFI SYSTEM (2AZ-FE)(From August, 2004)
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:
DATA LIST/ACTIIVE TEST/SYSTEM CHECK/SYSTEM CHECK
1. DATA LIST
HINT:
Using the hand-held tester DATA LIST allows switch, sensor, actuator and other item values to be read with-
out removing any parts. Reading the DATA LIST early in troubleshooting is one way to shorten labor time.
NOTICE:
In the table below, the values listed under ºNormal Conditionº are reference values. Do not depend
solely on the these reference values when deciding whether a part is faulty or not.
(a) Warm up the engine.
(b) Turn the ignition switch OFF.
(c) Connect the hand-held tester or the OBD II scan tool to the DLC3.
(d) Turn the ignition switch ON.
(e) Turn ON the hand-held tester or the OBD II scan tool.
(f) Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DATA LIST.
(g) According to the display on tester, read the ºDATA LISTº.
Hand-held Tester DisplayMeasurement Item/Range
(Display)Normal Condition*Diagnostic Note
INJECTORInjection period/
Minimum: 0 ms, Maximum: 32.64 msIdling: 1.92 to 3.37 ms-
IGN ADVANCEIgnition timing advance/
Minimum: -64 deg., Maximum: 63.5 deg.Idling: BTDC 5 to 15 deg.-
CALC LOADCalculated load by ECM/
Minimum: 0 %, Maximum: 100 %
Idling: 3.3 to 26.7 %

Racing without load (2500 rpm):
12.0 to 14.7 %
-
MAFAir flow rate from MAF meter/
Minimum: 0 gm/s, Maximum: 655 gm/s

Idling:
0.58 to 4.67 gm/second

Racing without load (2,500 rpm):
3.33 to 9.17 gm/second
If value is approximately 0.0 gm/s:

Mass air flow meter power
source circuit open

VG circuit open or short
If value is 160.0 gm/s or more:

EVG circuit open
ENGINE SPDEngine Speed/
Minimum: 0 rpm, Maximum: 16,383 rpmIdling:
550 to 750 rpm-
COOLANT TEMPCoolant temperature/
Minimum: -40C, Maximum: 140CAfter warming up: 80 to 95°C
(176 to 203°F)

If value is -40C (-40F): sensor
circuit is open

If value is 140C (284F) or
more:
sensor circuit is shorted
INTAKE AIRIntake air temperature/
Minimum: -40C, Maximum: 140CEquivalent to ambient temperature
(after cold soak)

If value is -40C (-40F): sensor
circuit is open

If value is 140C (284F) or
more:
sensor circuit is shorted
THROTTLE POSAbsolute throttle position sensor/
Minimum: 0 %, Maximum: 100 %
Throttle fully closed: 6 to 16 %

Throttle fully open: 64 to 98 %Read value with ignition switch ON
(do not start engine)
CTP SWClosed throttle position switch/
ON or OFF
Throttle fully closed: ON

Throttle open: OFF-
VEHICLE SPDVehicle speed/
Minimum: 0 km/h, Maximum: 255 km/hVehicle stopped: 0 km/h (0 mph)Speed indicated on speedometer
ACCEL POS #1
Accelerator pedal position sensor No.1
output voltage/
Minimum: 0 V, Maximum: 5 V
Accelerator released:
0.5 to 1.1 V

Accelerator depressed:
2.6 to 4.5 V
Read value with ignition switch ON
(do not start engine)
ACCEL POS #2
Accelerator pedal position sensor No. 2
output voltage/
Minimum: 0 V, Maximum: 5 V
Accelerator released:
1.2 to 2.0 V

Accelerator depressed:
3.4 to 5.3 V
Read value with ignition switch ON
(do not start engine)

05EXA-04
05-406
- DIAGNOSTICSSFI SYSTEM (3MZ-FE)(From August, 2004)
596 Author
: Date
:
DATA LIST/ACTIVE TEST
1. DATA LIST
HINT:
Using the hand-held tester DATA LIST allows switch, sensor, actuator and other item values to be read with-
out removing any parts. Reading the DATA LIST early in troubleshooting is one way to shorten labor time.
NOTICE:
In the table below, the values listed under ºNormal Conditionº are reference values. Do not depend
solely on these reference values when deciding whether a part is faulty or not.
(a) Warm up the engine.
(b) Turn the ignition switch OFF.
(c) Connect the hand-held tester or the OBD II scan tool to the DLC3.
(d) Turn the ignition switch ON.
(e) Turn ON the hand-held tester.
(f) Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DATA LIST.
(g) According to the display on tester, read the ºDATA LISTº.
Hand-held Tester DisplayMeasurement Item/Range
(Display)Normal Condition *Diagnostic Note
INJECTOR
Injection period of the No. 1 cylin-
der/
Minimum: 0 ms, Maximum: 32.64
ms
Idling: 1.5 to 2.8 ms'
IGN ADVANCE
Ignition timing advance for No. 1
cylinder/
Minimum: -64 deg., Maximum:
63.5 deg.
Idling: BTDC 5 to 25°'
CALC LOADCalculated load by ECM/
Minimum: 0 %, Maximum: 100 %
Idling: 10.4 to 15.6 %

Running without load (2,500
rpm): 12.1 to 18.2 %
'
MAF
Air flow rate from MAF meter/
Minimum: 0 gm/s, Maximum: 655
gm/s
Idling: 2.0 to 3.7 gm/s

Running without load (2,500
rpm): 2.4 to 4.3 gm/s
If value is approximately 0.0 gm/s:

Mass air flow meter power
source circuit open

VG circuit open or short
If value is 160.0 gm/s or more:

E2G circuit open
ENGINE SPD
Engine speed/
Minimum: 0 rpm, Maximum:
16,383 rpm
Idling: 580 to 750 rpm'
COOLANT TEMP
Coolant temperature/
Minimum: -40C, Maximum:
140CAfter warming up: 80 to 97°C
(176 to 207°F)
If value is -40C (-40F): sensor
circuit is open
INTAKE AIR
Intake air temperature/
Minimum: -40C, Maximum:
140CEquivalent to ambient temp.
(after cold soak)
circuit is oen

If value is 140C (284F or
more): sensor circuit is shorted
THROTTLE POSAbsolute throttle position sensor/
Minimum: 0 %, Maximum: 100 %
Throttle fully closed: 10 to 24 %

Throttle fully open: 64 to 96 %Read value with ignition switch ON
(do not start engine)
CTP SWClosed throttle position switch/
ON or OFF
Throttle fully closed: ON

Throttle open: OFF'
VEHICLE SPD
Vehicle speed/
Minimum: 0 km/h, Maximum: 255
km/h
Actual vehicle speedSpeed indicated on speedometer
ACCEL POS #1
Accelerator pedal position sensor
No.1 output voltage/
Minimum: 0 V, Maximum: 5 V
Accelerator pedal released:
0.5 to 1.1 V

Accelerator pedal depressed:
2.6 to 4.5 V
Read value with ignition switch ON
(do not start engine)

A80089
AB B+
Power Transistor
Platinum Hot Wire
(Heater)
Output
Voltage
Temperature
Sensor
Platinum Hot Wire (Heater)
Temperature Sensor
- DIAGNOSTICSSFI SYSTEM (2AZ-FE)
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:
2005 HIGHLANDER REPAIR MANUAL (RM1144U)
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, changing 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 air flow 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
P0100When MAF meter circuit has an open or a short for more than
3 seconds
Open or short in MAF meter circuit

MAF meter

ECM
P0102When MAF meter circuit has an open for more than 3 seconds
Same as DTC No. P0100
P0103When MAF meter circuit has a short for more than 3 seconds
Same as DTC No. P0100
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).
Air Flow Value (g/s)Malfunction
Approximately 0.0
Open in MAF meter power source circuit

Open or short in VG circuit
271.0 or more
Open in EVG circuit
05ESV-05

A54396
+B (+) Wire Harness Side
M1
MAF Meter
05-84
- DIAGNOSTICSSFI SYSTEM (2AZ-FE)
274 Author
: Date
:
2005 HIGHLANDER REPAIR MANUAL (RM1144U)
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 READ VALUE OF HAND-HELD TESTER OR OBD II SCAN TOOL (MAF RATE)
(a) Connect the hand-held tester or the OBD II scan tool to the DLC3.
(b) Start the engine.
(c) Push the hand-held tester or the OBD II scan tool main switch ON.
(d) On the hand-held tester or the OBD II scan tool, enter the following menus: DIAGNOSIS / ENHANCED
OBD II / DATA LIST / ALL / MAF. Read the values.
Result:
Air Flow Rate (gm/second)Proceed to
0.0A
271.0 or moreB
MAF rate greater than 1 but less than 270.0 *C
HINT:
*: The value must change when the throttle valve is opened or closed.
B Go to step 6
C CHECK FOR INTERMITTENT PROBLEMS
(See page 05-9)
A
2 CHECK MASS AIR FLOW METER (POWER SOUCE VOLTAGE)
(a) Turn the ignition switch ON.
(b) Disconnect the M1 MAF meter connector.
(c) Measure the voltage of the wire harness side connector.
Standard:
Tester ConnectionSpecified Condition
M1-1 (+B) - Body ground9 to 14 V
NG Go to step 5
OK

A76903
VG (+) EVG (-)
E7
ECM
Y
A54396
A81699
A85482
Wire Harness Side
M1
MAF Meter
EVG VG
E7
ECM
EVG
VG
- DIAGNOSTICSSFI SYSTEM (2AZ-FE)
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275 Author
: Date
:
2005 HIGHLANDER REPAIR MANUAL (RM1144U)
3 INSPECT ECM (VG VOLTAGE)
(a) Start the engine.
(b) Measure the voltage of the ECM connector.
Standard:
Tester ConnectionConditionSpecified Condition
E7-30 (VG) - E7-29 (EVG)Engine is idling0.5 to 3.0 V
HINT:
The shift position should be P or N and the A/C switch should
be turned OFF.
OK REPLACE ECM (See page 10-9)
NG
4 CHECK WIRE HARNESS (MAF METER - ECM)
(a) Disconnect the M1 MAF meter connector.
(b) Disconnect the E7 ECM connector.
(c) Measure the resistance of the wire harness side connec-
tors.
Standard:
Tester ConnectionSpecified Condition
M1-3 (VG) - E7-30 (VG)
M1-2 (EVG) - E7-29 (EVG)Below 1 W
M1-3 (VG) or E7-30 (VG) - Body ground10 kW or higher
NG REPAIR OR REPLACE HARNESS AND
CONNECTOR
OK
REPLACE MASS AIR FLOW METER

Y
A54396
A81699
A85482
Wire Harness Side
M1
MAF Meter
EVG VG
E7
ECM
EVG
VG
- DIAGNOSTICSSFI SYSTEM (2AZ-FE)
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277 Author
: Date
:
2005 HIGHLANDER REPAIR MANUAL (RM1144U)
7 CHECK WIRE HARNESS (MAF METER - ECM)
(a) Disconnect the M1 MAF meter connector.
(b) Disconnect the E7 ECM connector.
(c) Measure the resistance of the wire harness side connec-
tors.
Standard:
Tester ConnectionSpecified Condition
M1-3 (VG) - E7-30 (VG)
M1-2 (EVG) - E7-29 (EVG)Below 1 W
M1-3 (VG) or E7-30 (VG) - Body ground10 kW or higher
NG REPAIR OR REPLACE HARNESS AND
CONNECTOR
OK
REPLACE MASS AIR FLOW METER