Lexus RX300 (MCU15). Manual — part 398
N16207
Thermometer
Ice
More than
10 cm (3.94in.)
DI–822
–
DIAGNOSTICS
AIR CONDITIONING SYSTEM
LEXUS RX300 (RM785E)
3
Check evaporator temperature sensor.
PREPARATION:
Remove evaporator temperature sensor (See page AC–67).
CHECK:
Measure resistance between terminals 1 and 2 of evaporator
temperature sensor connector at each temperature.
OK:
Resistance :
at 0
°C (32°F) : 4.5 – 5.2 kΩ
at 15
°C (59°F) : 2.0 – 2.7 kΩ
HINT:
As the temperature increases, the resistance decreases.
NG
Replace evaporator temperature sensor.
OK
4
Check harness and connector between A/C ECU (Combination meter ECU) and
evaporator temperature sensor (See page IN–32).
NG
Repair or replace harness or connector.
OK
Check and replace A/C ECU (Combination
meter ECU).
Resistance of photodiode
High
Low
Weak
Strong
Strength of solar radiation
I08369
Solar Sensor
A/C ECU (Combina-
tion meter ECU)
1
2
Y–B
L
C11
15
TS
S5–3
16
C11
–
DIAGNOSTICS
AIR CONDITIONING SYSTEM
DI–823
LEXUS RX300 (RM785E)
DTC
B1421/21 Solar Sensor Circuit
CIRCUIT DESCRIPTION
A photo diode in the solar sensor detects solar radiation and
sends signals to the A/C ECU (Combination meter ECU).
DTC No.
Detection Item
Trouble Area
B1421/21
Open or short in solar sensor circuit.
Please note that display of diagnostic trouble code 21 is not
abnormal when the sensor is not receiving solar radiation.
S Solar sensor.
S Harness or connector between solar sensor and A/C ECU
(Combination meter ECU).
S A/C ECU (Combination meter ECU).
WIRING DIAGRAM
DI3FX–02
I08337
TS
S5–3
(+)
(–)
DI–824
–
DIAGNOSTICS
AIR CONDITIONING SYSTEM
LEXUS RX300 (RM785E)
INSPECTION PROCEDURE
HINT:
In case of using the hand–held tester, start the inspection step 1 and in case of not using the hand–held
tester, start from step 2.
1
Check solar sensor using hand–held tester.
PREPARATION:
Connect the hand–held tester to the DLC3.
CHECK:
Check the solar sensor using DATA LIST.
OK
Check and replace A/C ECU (Combination me-
ter ECU).
NG
2
Check voltage between terminals TS and S5–3 of A/C ECU (Combination meter
ECU) connector.
PREPARATION:
Remove A/C ECU with connectors still connected.
CHECK:
(a)
Turn ignition switch ON.
(b)
Measure voltage between terminals TS and S5–3 of A/C
ECU connector when the solar sensor is subjected to an
electric light, and when the sensor is covered by al cloth.
OK:
Condition
Voltage
Sensor subjected to electric light
0.8 – 4.3 V
Sensor covered by a cloth
Below 0.8 V
HINT:
As the inspection light is moved away from the sensor, the volt-
age increases.
NG
go to step 3.
OK
Proceed to next circuit inspection shown on problem symptoms table (See page DI–812). Howev-
er, if DTC B1421/21 is displayed, check and replace A/C ECU (Combination meter ECU).
I08357
2
1
–
DIAGNOSTICS
AIR CONDITIONING SYSTEM
DI–825
LEXUS RX300 (RM785E)
3
Check solar sensor.
PREPARATION:
Remove solar sensor.
CHECK:
(a)
Cover the sensor by a cloth.
(b)
Measure resistance between terminals 1 and 2 of solar
sensor connector.
HINT:
Connect positive (+) lead of ohmmeter to terminal 1 and nega-
tive (–) lead to terminal 2 of the solar sensor.
OK:
Resistance : ∞ Ω (no continuity)
PREPARATION:
(a)
Remove the cloth from the solar sensor and subject the
sensor to electric light.
(b)
Measure resistance.
OK:
Resistance : Approx. 4 kΩ (continuity)
HINT:
As the electric light is moved away from the sensor, the resis-
tance increases.
NG
Replace solar sensor.
OK
4
Check harness and connector between A/C ECU (Combination meter ECU) and
solar sensor (See page IN–32).
NG
Repair or replace harness or connector.
OK
Check and replace A/C ECU (Combination
meter ECU).
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