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 

SF–80

).

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 

DI–11

).

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