Toyota Tundra 2005 Service - Repair - Maintenance page 1103

DI−818
3 Read value output voltage of A/F sensor.
PREPARATION:
(a) Connect the hand−held tester to the DLC3.
(b) Start the engine and turn the scan tool ON.
(c) Warm up the Air−Fuel Ratio (A/F) sensor at an engine speed of 2,500 rpm for 90 seconds.
CHECK:
(a) Using the scan tool, check the A/F sensor voltage 3 times, once when the engine is in each of the fol-
lowing conditions:
(1) While idling (check for at least 30 seconds)
(2) At an engine speed of approximately 2,500 rpm (without any sudden changes in engine speed)
(3) Raise the engine speed to 4,000 rpm and then quickly release the accelerator pedal so that the
throttle valve is fully closed.
Standard:
Conditions
(1) and (2)
(3)
For more information, see the diagrams below.
Normal Condition:
(2) Approximately 2,500 rpm
(1) Idling
Engine
RPM
A/F
Sensor
Voltage
"Condition (1), (2)"
Change at approximately 0.66 V
HINT:
S
If the output voltage of the A/F sensor remains at approximately 0.66 V (see Malfunction Condition
diagram) under any conditions, including those above, the A/F sensor may have an open circuit. (This
will also happen if the A/F sensor heater has an open circuit.)
S
If the output voltage of the A/F sensor remains at either approximately 0.76 V or more, or 0.56 V or
less (see Malfunction Condition diagram) under any conditions, including those above, the A/F sensor
may have a short circuit.
S
The ECM stops fuel injection (fuel cut) during engine deceleration. This causes a lean condition and
results in a momentary increase in the A/F sensor output voltage.
DIAGNOSTICS
A/F Sensor Voltage Variations
Changes at approx 0.66 V
Increases to 0.76 V or more
(3) Approximately 4,000 rpm
(1) Idling
"Condition (3)"
0.76 V or More
Fuel Cut
− ENGINE (2UZ−FE)
Between 0.62 V and 0.7 V
This occurs during engine deceleration
(when fuel−cut performed)
Malfunction Condition:
(2) Approximately 2,500 rpm
(1) Idling
Engine
RPM
A/F
Sensor
Voltage
When A/F sensor circuit malfunctioning,
voltage output does not change
Reference
(3) Approximately 4,000 rpm
(1) Idling
Fuel Cut
B17393