Toyota Sequoia (2005). Manual - part 93

A19288

A/F Relay

A23659

Wire Harness Side:

HT

A38

Sensor 1

A/F Sensor Connector

AF+

Front View

AF–

+B

A39

B17415

E7 ECM Connector

HA1A

A1A+

A1A–

A2A+

A2A–

HA2A

–

DIAGNOSTICS

ENGINE

DI–175

369

12

Check A/F relay.

PREPARATION:
Remove the A/F relay from the engine room J/B.
CHECK:
Inspect the A/F 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 A/F relay.

OK

13

Check for open and short in harness and connector between ECM and A/F sen-
sor.

PREPARATION:
(a)

Disconnect the A38 or A39 A/F sensor connector.

(b)

Turn the ignition switch to ON.

CHECK:
(a)

Measure the voltage between the +B terminal of the A/F
sensor connector and body ground.

OK:

Standard:

Tester Connections

Specified Conditions

+B (2) – Body ground

9 to 14 V

PREPARATION:
(a)

Turn the ignition switch to OFF.

(b)

Disconnect the E7 ECM connector.

CHECK:
(a)

Check the resistance.

OK:

Standard (Check for open):

Tester Connections

Specified Conditions

HT (A38–1) – HA1A (E7–2)

HT (A39–1) – HA2A (E7–1)

Below 1 

Ω

AF+ (A38–3) – A1A+ (E7–22)

AF+ (A39–3) – A2A+ (E7–23)

Below 1 

Ω

AF– (A38–4) – A1A– (E7–30)

AF– (A39–4) – A2A– (E7–31)

Below 1 

Ω

A23512

Reference (Bank 1 Sensor 1 System Drawing):

A/F Sensor

A/F Relay

Heater

Sensor

A1A+

HA1A

Duty 
Control

ECM

From 
Battery

A/F Heater 
Fuse

A1A–

To EFI Relay

DI–176

–

DIAGNOSTICS

ENGINE

370

Standard (Check for short):

Tester Connections

Specified Conditions

HT (A38–1) or HA1A (E7–2) – Body ground
HT (A39–1) or HA2A (E7–1) – Body ground

10 k

Ω

 or higher

AF+ (A38–3) or A1A+ (E7–22) – Body ground
AF+ (A39–3) or A2A+ (E7–23) – Body ground

10 k

Ω

 or higher

AF– (A38–4) or A1A– (E7–30) – Body ground
AF– (A39–4) or A2A– (E7–31) – Body ground

10 k

Ω

 or higher

NG

Replace or replace harness or connector.

OK

14

Replace air fuel ratio sensor.

NEXT

B17397

Vehicle Speed

Between 
38 mph and 75 mph 
(60 km/h and 120 km/h)

Idling

Ignition Switch OFF

3 to 5 minutes

Time

2 minutes

(a), (b), (c)

(e)

(d)

–

DIAGNOSTICS

ENGINE

DI–177

371

15

Perform confirmation driving pattern.

(a)

Connect the hand–held tester to the DLC3.

(b)

Turn the ignition switch to ON and turn the tester ON.

(c)

Clear DTCs (see page 

DI–43

).

(d)

Switch the ECM from normal mode to check mode using the tester (see page 

DI–44

).

(e)

Start the engine and warm it up with all the accessories switched OFF.

(f)

Drive the vehicle at between 38 mph and 75 mph (60 km/h and 120 km/h) and at an engine speed of
between 1,400 rpm and 3,200 rpm for 3 to 5 minutes.

HINT:
If the system is still malfunctioning, the MIL will be illuminated during step (e).
NOTICE:
If the conditions in this test are not strictly followed, no malfunction will be detected.

NEXT

16

Check whether DTC output recurs (DTC P0171, P0172, P0174 or P0175)

CHECK:
(a)

On the hand–held tester, select the following menu items: DIAGNOSIS / ENHANCED OBD II / DTC
INFO / PENDING CODES.

(b)

Read DTCs.

RESULT:

Display (DTC Output)

Proceed To

P0171, P0172, P0174 or P0175

A

No output

B

B

Go to step 5.

A

DI–178

–

DIAGNOSTICS

ENGINE

372

END