Lexus SC300 / Lexus SC400. Manual — part 624

Disconnect terminals TE1 and E1 of the check connector.
And maintain engine at 2,500 rpm.

Repair (Over rich)

Replace the oxygen sensor.

Repair (Over rich)

Measure voltage between terminals VF1 (VF2) and E1.

Disconnect the PCV hose.

Measure voltage between terminals VF1 (VF2) and E1.

Disconnect the water temp. sensor connector and connect
resistor with a resistance of 4 – 8 k

or another coded water

temp. sensor.

Connect terminals TE1 and E1 of the check connector.

Warm up the oxygen sensors with the engine at 2,500 rpm for
approx. 120 seconds. and maintain engine at 2,500 rpm.

Measure voltage between terminals VF1 (VF2) and E1.

5 V

CONTINUED FROM PAGE

FI–114

0 V

0 V

0 V

5 V

More than 0 V

FI–115

EFI SYSTEM – Electronic Control System (Main Oxygen Sensors)

3.

DISCONNECT CABLE FROM NEGATIVE TERMINAL OF
BATTERY
CAUTION: Work must be started after approx. 20 se-
conds or longer from the time the ignition switch is
turned to the ”LOCK” position and the negative (–) termi-
nal cable is disconnected from the battery.

4. INSPECT

HEATER

RESISTANCE OF MAIN OXYGEN

SENSORS
(a) Disconnect the oxygen sensor connectors.
(b) Using an ohmmeter, measure the resistance between

the terminals +B and HT.

Resistance: 5.1–6.3

at 20

°

C (68

°

F)

If the resistance is not as specified, replace the sensor.

Torque: 44 N

⋅

m (450 kgf

⋅

cm, 33 ft

⋅

lbf)

(c) Reconnect the oxygen sensor connectors.

5. RECONNECT CABLE TO NEGATIVE TERMINAL OF

BATTERY

FI–116

EFI SYSTEM – Electronic Control System (Main Oxygen Sensors)

Sub–Oxygen Sensors

COMPONENTS FOR REMOVAL AND
INSTALLATION

FI–117

– Electronic Control System (Sub–Oxygen Sensors)

EFI SYSTEM

INSPECTION OF SUB–OXYGEN
SENSORS

1.

INSPECT SUB–OXYGEN SENSORS
(a) Cancel diagnostic code. (See TR section)
(b) Allow the engine to warm up to normal operating

temperature.

(c) Drive for 5 minutes or more between 80km/h (50 mph)

and 100 km/h (62 mph) in ”D” range.

(d) Following the conditions in step (c), press fully on the

accelerator pedal for 2 seconds or more.

HINT: Do not exceed 100 km/h (62 mph), or diagnostic code
will be cancelled.
(e) Stop the vehicle, and turn the ignition switch to OFF.
(f) Carry

out steps (b), (c) and (d) again to test acceleration.

If code No.27 reappears again, check the sub–oxygen sen-
sor circuit. If the circuit is normal, replace the sub–oxygen
sensor.

2.

DISCONNECT CABLE FROM NEGATIVE TERMINAL OF
BATTERY
CAUTION: Work must be started after approx. 20 se-
conds or longer from the time the ignition switch is
turned to the ”LOCK” position and the negative (–) termi-
nal cable is disconnected from the battery.

3.

REMOVE TRANSMISSION SHIFT LEVER KNOB
(a) Push down the lever cover.

(b) Remove the two screws and shift lever knob.
(c) Remove the lever cover.

FI–118

EFI SYSTEM – Electronic Control System (Sub–Oxygen Sensors)