Toyota Tundra. Manual — part 1422

HINT:

Malfunctioning areas can be identified by performing the Control the Injection Volume for A/F sensor function
provided in the Active Test. The Control the Injection Volume for A/F sensor function can help to determine
whether the Air-Fuel Ratio (A/F) sensor, Heated Oxygen (HO2) sensor and other potential trouble areas are
malfunctioning.

The following instructions describe how to conduct the Control the Injection Volume for A/F sensor operation
using the Techstream.

a. Connect the Techstream to the DLC3.

b. Start the engine and turn the Techstream ON.

c. Warm up the engine at an engine speed of 2500 RPM for approximately 90 seconds.

d. Enter the following menus: Powertrain/Engine and ECT/Active Test/Control the Injection Volume for

A/F sensor.

e. Perform the Active Test operation with the engine idling (press the RIGHT or LEFT button to change the

fuel injection volume).

f. Monitor the output voltages of the A/F and HO2 sensors (AFS B1 S1 and O2S B1 S2 or AFS B2 S1 and

O2S B2 S2) displayed on the Techstream.

HINT:



The Control the Injection Volume for A/F sensor operation lowers the fuel injection volume by 12.5% or
increases the injection volume by 25%.



Each sensor reacts in accordance with increases and decreases in the fuel injection volume.

Standard

FUEL INJECTION - VOLTAGE SPECIFICATION

A/F SENSOR (SENSOR 1) OUTPUT VOLTAGE SPECIFICATION

Tester Display (Sensor)

Injection Volume

Status

Voltage

AFS B1 S1 (A/F)

+25%

Rich

Less than 3.0

-12.5%

Lean

More than 3.35

O2S B1 S2 (HO2)

+25%

Rich

More than 0.55

-12.5%

Lean

Less than 0.4

AFS B2 S1 (A/F)

+25%

Rich

Less than 3.0

-12.5%

Lean

More than 3.35

O2S B2 S2 (HO2)

+25%

Rich

More than 0.55

-12.5%

Lean

Less than 0.4

NOTE:

The A/F sensor has an output delay of a few seconds and the HO2 sensor has a
maximum output delay of approximately 20 seconds.

A/F Sensor (Sensor 1) Output

HO2 Sensor (Sensor 2)

2008 Toyota Tundra

2008 ENGINE PERFORMANCE Engine Control System (2UZ-FE) - Tundra

Following the Control the Injection Volume for A/F Sensor procedure enables technicians to check and graph
the output voltages of both the A/F and HO2 sensors.

Enter the following menus: Powertrain/Engine and ECT/Active Test/Control the Injection Volume for A/F
Sensor/ A/F Control System/AFS B1 S1 and O2S B1 S2 or AFS B2 S1 and O2S B2 S2.

HINT:

Read freeze frame data using the Techstream. Freeze frame data records the engine condition when
malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was
moving or stationary, 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. CHECK HARNESS AND CONNECTOR (A/F SENSOR - ECM) (See INSPECTION

PROCEDURE )

NG : REPAIR OR REPLACE HARNESS OR CONNECTOR

OK : Go to Next Step

2. REPLACE AIR FUEL RATIO SENSOR

a. Replace the air fuel ratio sensor. (See REMOVAL ).

3. CHECK WHETHER DTC OUTPUT RECURS

a. Connect the Techstream to the DLC3.

b. Turn the ignition switch to ON and turn the Techstream ON.

Case

Voltage

Output Voltage

Main Suspected Trouble Area

1

-

2



A/F sensor



A/F sensor heater



A/F sensor circuit

3



HO2 sensor



HO2 sensor heater



HO2 sensor circuit

4



Injector



Fuel pressure



Gas leakage from exhaust
system (Air-fuel ratio
extremely rich or lean)

2008 Toyota Tundra

2008 ENGINE PERFORMANCE Engine Control System (2UZ-FE) - Tundra

c. Clear DTCs. (See DTC CHECK/CLEAR ).

d. Start the engine.

e. Allow the engine to idle for 5 minutes or more.

f. Enter the following menus: Powertrain/Engine and ECT/Trouble Codes/Pending.

g. Read pending DTCs.

Result

RESULT REFERENCE

B : REPLACE ECM (See REMOVAL )

A : END

DTC P2420 EVAPORATIVE EMISSION SYSTEM SWITCHING VALVE CONTROL CIRCUIT
HIGH

DTC SUMMARY

DTC SUMMARY

HINT:

The vent valve is built into the canister pump module.

DESCRIPTION

The description can be found in the EVAP (Evaporative Emission) System. (See DESCRIPTION ).

Result

Proceed

To

No DTC is output

A

P2237, P2238, P2239, P2240, P2241, P2242, P2252, P2253, P2255 or P2256 is
output

B

DTC

Monitoring

Item

Malfunction Detection

Condition

Trouble Area

Detection

Timing

Detection

Logic

P2420

Vent valve
stuck open
(vent)

Following condition met
during key-off EVAP
monitor:



EVAP pressure
change when vent
valve closed (ON)
less than 0.3 kPa-g
(2.25 mmHg-g)



Canister pump module
(Reference orifice, leak
detection pump, vent
valve)



Connector/wire harness
(Canister pump module
- ECM)



ECM

While
ignition
switch off

2 trip

2008 Toyota Tundra

2008 ENGINE PERFORMANCE Engine Control System (2UZ-FE) - Tundra

INSPECTION PROCEDURE

Refer to the EVAP SYSTEM .

MONITOR DESCRIPTION

5 hours* after the ignition switch is turned off, the leak detection pump creates negative pressure (vacuum) in
the EVAP system. The ECM monitors for leaks and actuator malfunctions based on the EVAP pressure.

HINT:

*: If the engine coolant temperature is not below 35°C (95°F) 5 hours after the ignition switch is turned off, the
monitor check starts 2 hours later. If it is still not below 35°C (95°F) 7 hours after the ignition switch is turned
off, the monitor check starts 2.5 hours later.

MONITOR DESCRIPTION

Sequence

Operation

Description

Duration

-

ECM activation

Activated by soak timer 5, 7 or 9.5 hours after ignition switch
turned off.

-

A

Atmospheric
pressure
measurement

Vent valve turned OFF (vent) and EVAP system pressure
measured by ECM in order to register atmospheric pressure.
If pressure in EVAP system not between 70 kPa-a and 110
kPa-a (525 mmHg-a and 825 mmHg-a), ECM cancels EVAP
system monitor.

10

seconds

B

First reference
pressure
measurement

In order to determine reference pressure, leak detection pump
creates negative pressure (vacuum) through reference orifice
and then ECM checks if leak detection pump and vent valve
operate normally.

60

seconds

C

EVAP system
pressure
measurement

Vent valve turned ON (closed) to shut EVAP system.
Negative pressure (vacuum) created in EVAP system, and
EVAP system pressure then measured.
Write down measured value as it will be used in leak check.
If EVAP pressure does not stabilize within 15 minutes, ECM
cancels EVAP system monitor.

15

minutes

(1)

D

Purge VSV monitor

Purge VSV opened and then EVAP system pressure measured
by ECM.
Large increase indicates normality.

10

seconds

E

Second reference
pressure
measurement

After second reference pressure measurement, leak check
performed by comparing first and second reference pressure.
If stabilized system pressure higher than second reference
pressure, ECM determines that EVAP system leaking.

60

seconds

-

Final check

Atmospheric pressure measured and then monitoring result
recorded by ECM.

-

(1)

If only a small amount of fuel is in the fuel tank, it takes longer for the EVAP pressure to stabilize.

2008 Toyota Tundra

2008 ENGINE PERFORMANCE Engine Control System (2UZ-FE) - Tundra