Toyota Sequoia (2005). Manual - part 88

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DIAGNOSTICS

ENGINE

DI–155

349

INSPECTION PROCEDURE

HINT:
Hand–held tester only:
Narrowing down the trouble area is possible by performing ACTIVE TEST of the following ”A/F CONTROL”
(Heated oxygen sensor or another can be distinguished).
(a)

Perform ACTIVE TEST by hand–held tester (A/F CONTROL).

HINT:
”A/F CONTROL” is the ACTIVE TEST which changes the injection volume to –12.5 % or +25 %.

(1)

Connect the hand–held tester to the DLC3 on the vehicle.

(2)

Turn the ignition switch ON.

(3)

Warm up the engine with the engine speed at 2,500 rpm for approximately 90 seconds.

(4)

Select the menu ”DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL”.

(5)

Perform ”A/F CONTROL” with the engine in an idle condition (press the right or left button).

RESULT:

Heated oxygen sensor reacts in accordance with increase and decrease of injection volume
+25 % 

→

 rich output: More than 0.5 V

–12.5 % 

→

 lean output: Less than 0.4 V

NOTICE:
There is a few seconds delay in the sensor 1 (front sensor) output. And there is approximately 20
seconds delay in the sensor 2 (rear sensor).

+25 %

–12.5 %

More than 0.5 V

Less than 0.4 V

Case 1

Case 2

Case 3

Case 4

Output voltage of A/F sensor 
(sensor 1: front sensor)

Injection volume

Output voltage

Output voltage of heated oxygen 
sensor (sensor 2: rear sensor)

Mainly suspected 
trouble area

OK

+25 %

–12.5 %

More than 0.5 V

Less than 0.4 V

Injection volume

Output voltage

+25 %

–12.5 %

More than 0.5 V

Less than 0.4 V

Injection volume

Output voltage

Sensor 1: front sensor
(sensor 1, heater, sensor 1 
circuit)

+25 %

–12.5 %

More than 0.5 V

Less than 0.4 V

Injection volume

Output voltage

+25 %

–12.5 %

Injection volume

Output voltage

NG

+25 %

–12.5 %

Injection volume

Output voltage

NG

+25 %

–12.5 %

Injection volume

Output voltage

NG

+25 %

–12.5 %

Injection volume

Output voltage

NG

Extremely rich or lean actual
air–fuel ratio
(Injector, fuel pressure, gas
leakage in exhaust system,
etc.)

OK

OK

OK

Almost
no reaction



Sensor 2: rear sensor
(sensor 2, heater, sensor 2 
circuit)

Almost
no reaction

Almost
no reaction

Almost
no reaction

DI–156

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DIAGNOSTICS

ENGINE

350

The following A/F CONTROL procedure enables the technician to check and graph the voltage output of
the heated oxygen sensors.
For displaying the graph indication, first enter ”ACTIVE TEST / A/F CONTROL / USER DATA,” then select
”A/F B1,2S1and O2S B1,2S2” by pressing ”YES” button, and push ”ENTER” button before pressing ”F4”
button.

HINT:

If different DTCs that are related to different system are output simultaneously while terminal E2 is used
as a ground terminal, terminal E2 may be open.

Read freeze frame data using 

the hand−held tester

. Freeze frame data records the engine conditions

when a malfunction is detected. When troubleshooting, it is useful for determining 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.

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DIAGNOSTICS

ENGINE

DI–157

351

1

Read output DTC.

PREPARATION:
(a)

Connect the hand–held tester to the DLC3.

(b)

Turn the ignition switch ON and push the hand–held tester main switch ON.

(c)

When using hand–held tester, enter the following menu: DIAGNOSIS / ENHANCED OBD II / DTC
INFO / CURRENT CODES.

CHECK:
Read the DTC using the hand–held tester.
RESULT:

Display (DTC Output)

Proceed to

P0138, P0158

A

P0137, P0157

B

P0136, P0156

C

HINT:
If any other codes besides P0136, P0137, P0138, P0156, P0157 and/or P0158 are output, perform the trou-
bleshooting for those DTCs first.

B

Go to step 14.

C

Go to step 7.

A

2

Check output voltage of heated oxygen sensor.

PREPARATION:
(a)

Connect the  hand–held tester to the DLC3.

(b)

After warming up the engine, run the engine at 2,500 rpm for 3 minutes.

(c)

When using hand–held tester, enter the following menu: DIAGNOSIS / ENHANCED OBD II / DATA
LIST / ALL / O2S B1S2 or B2S2.

(d)

Allow the engine to idle.

CHECK:
Read the Heated Oxygen (HO2) sensor output voltage while idling.
RESULT:

HO2 Sensor Output Voltages

Proceed To

More than 1.2 V

A

Less than 1.0 V

B

B

Go to step 5.

A

B17416

HT1B

ECM Connector

E7

OX1B

E8

HT2B

OX2B

A21341

+B

OX

E1

HT

H2

H4

Components Side:

Bank 1 Sensor 2, Bank 2 Sensor 2

DI–158

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DIAGNOSTICS

ENGINE

352

3

Check for short in harness and connector between terminal OX1B and HT1B,
OX2B and HT2B of ECM.

PREPARATION:
(a)

Turn the ignition switch to OFF and wait for 5 minutes.

(b)

Disconnect the E7 and E8 ECM connector.

CHECK:
(a)

Check the resistance.

OK:

Standard:

Tester Connections

Specified Conditions

HT1B (E8–1) – OX1B (E8–18)

10 k

Ω

 or higher

HT2B (E7–5) – OX2B (E5–33)

10 k

Ω

 or higher

OK

Replace ECM (See page 

SF–80

NG

4

Check resistance of heated oxygen sensor heater.

PREPARATION:
Disconnect the heated oxygen sensor connector.
CHECK:
Measure resistance between terminals of the heated oxygen
sensor.
OK:

Standard:

Tester Connection

Specified Condition

HT (1) – +B (2)

11 to 16 

Ω

 at 20

°

C (68

°

F)

+B (2) – OX (3)

10 k

Ω

 or higher

NG

Replace heated oxygen sensor.

OK

Repair or replace harness or connector.

5

Perform confirmation driving pattern.

NEXT