Toyota Sequoia (2005). Manual — part 74
A21341
+B
OX
E1
HT
H2
H4
Components Side:
Bank 1 Sensor 2, Bank 2 Sensor 2
A19288
EFI Relay
–
DIAGNOSTICS
ENGINE
DI–99
293
INSPECTION PROCEDURE
HINT:
Read freeze frame data using hand–held tester. Because freeze frame records the engine conditions when
the malfunction is detected. When troubleshooting, it is useful to determine whether the vehicle was running
or stopped, the engine was warmed up or not, the air–fuel ratio was lean or rich, etc. when a malfunction
occurred.
1
Check resistance of heated oxygen sensor heater.
PREPARATION:
Disconnect the H2 or H4 heated oxygen sensor connector.
CHECK:
Measure resistance between terminals of the heated oxygen
sensor.
OK:
Standard:
Tester Connection
Specified Condition
HTL2 (H2–1) – +B (H2–2)
11 to 16
Ω
(20
°
C)
HTR2 (H4–1) – +B (H4–2)
11 to 16
Ω
(20
°
C)
NG
Replace heated oxygen sensor.
OK
2
Check EFI relay.
PREPARATION:
Remove the EFI relay from the engine room J/B.
CHECK:
Inspect the EFI relay.
OK:
Standard:
Terminal No.
Condition
Specified Condition
3 – 5
Always
10 K
Ω
or higher
3 – 5
Apply B+ between
terminals 1 and 2
Below 1
Ω
NG
Replace EFI relay.
OK
B17411
HT1B
E7
HT2B
E8
DI–100
–
DIAGNOSTICS
ENGINE
294
3
Check voltage between terminals 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 HT1B to the bank 1 sensor 2.
Connect terminal HT2B to the bank 2 sensor 2.
OK:
Standard:
Tester Connection
Specified Condition
HT1B (E8–1) – Body ground
9 to 14 V
HT2B (E7–5) – Body ground
9 to 14 V
OK
Replace ECM (See page
NG
A23543
+B
OXR2
OXL2
E1
HTR2
HTL2
H2
H4
Wire Harness Side:
Bank 1 Sensor 2, Bank 2 Sensor 2
B17416
HT1B
ECM Connector
E7
OX1B
E8
HT2B
OX2B
H24254
Engine Room R/B:
EFI Relay
–
DIAGNOSTICS
ENGINE
DI–101
295
4
Check for open and short in harness and connector between ECM and heated
oxygen sensor, heated oxygen sensor – EFI relay.
PREPARATION:
(a)
Turn the ignition switch to OFF.
(b)
Disconnect the H2 or H4 oxygen sensor connector.
(c)
Disconnect the E7and E8 ECM connector.
CHECK:
Check the resistance.
OK:
Standard (Check for open):
Tester Connections
Specified Conditions
HTL2 (H2–1) – HT1B (E8–1)
Below 1
Ω
HTR2 (H4–1) – HT2B (E7–5)
Below 1
Ω
Standard (Check for short):
Tester Connections
Specified Conditions
HTL2 (H2–1) or HT1B (E8–1) –
Body ground
10 k
Ω
or higher
HTR2 (H4–1) or HT2B (E7–5) –
Body ground
10 k
Ω
or higher
PREPARATION:
(a)
Turn the ignition switch to OFF.
(b)
Disconnect the H2 or H4 oxygen sensor connector.
(c)
Remove EFI relay from engine room R/B.
CHECK:
Check the resistance.
OK:
Standard (Check for open):
Tester Connections
Specified Conditions
+B (A21–2) –EFI relay (3)
+B (A22–2) – EFI relay (3)
Below 1
Ω
Standard (Check for short):
Tester Connections
Specified Conditions
+B (H2–2) or EFI relay (3) – Body ground
+B (H2–2) or EFI relay (3) – Body ground
10 k
Ω
or higher
NG
Repair or replace harness or connector.
OK
Check for intermittent problems
(See page
FI6929
A09074
A09707
Power Transistor
Output
Voltage
A
B
B+
Temperature Sensor
Platinum Hot Wire
Temperature Sensor
Platinum Hot Wire
DI–102
–
DIAGNOSTICS
ENGINE
296
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 Condition
Trouble Area
P0100
Open or short in mass air flow meter circuit for more than 3
sec.
P0102
Open 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
DICEN–02
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