Lexus RX300 (MCU15). Service manual — part 397
I08332
TAM
SG–5
(+)
(–)
DI–818
–
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 form step 2.
1
Check ambient temp. sensor using hand–held tester.
PREPARATION:
Connect the hand–held tester to the DLC3.
CHECK:
Check the ambient temp. sensor using DATA LIST.
OK
Check and replace A/C ECU (Combination me-
ter ECU).
NG
2
Check voltage between terminals TAM and SG–5 of A/C ECU (combination meter
ECU).
PREPARATION:
Remove A/C ECU with connectors still connected.
CHECK:
(a)
Turn ignition switch ON.
(b)
Measure voltage between terminals TAM and SG–5 of
A/C ECU connector at each temperature.
OK:
Voltage :
at 25
°C (77°F) : 1.35 – 1.75 V
at 40
°C (104°F) : 0.85 – 1.25 V
HINT:
As the temperature increases, the voltage decreases.
NG
Go to step 3.
OK
Proceed to next circuit inspection shown on problem symptoms table (See page DI–812). Howev-
er, if DTC B1412/12 is displayed, check and replace ECM and A/C ECU (Combination meter ECU).
I08333
2
1
–
DIAGNOSTICS
AIR CONDITIONING SYSTEM
DI–819
LEXUS RX300 (RM785E)
3
Check ambient temperature sensor.
PREPARATION:
Disconnect ambient temperature sensor connector.
CHECK:
Measure resistance between terminals 1 and 2 of ambient tem-
perature sensor connector at each temperature.
OK:
Resistance :
at 25
°C (77°F) : 1.6 – 1.8 kΩ
at 50
°C (122°F) : 0.5 – 0.7 kΩ
HINT:
As the temperature increases, the resistance decreases.
NOTICE:
When installing the ambient temperature sensor, be sure to
connect the sensor connector before connecting the bat-
tery.
NG
Replace ambient temperature sensor.
OK
4
Check harness and connector between A/C ECU (combination meter ECU) and
ambient temperature sensor (See page IN–32).
NG
Repair or replace harness or connector.
OK
Check and replace A/C ECU (Combination
meter ECU).
I08334
A17
Evaporator
Temp. Sensor
1
2
B–Y
10
5 V
A/C ECU (Combina-
tion meter ECU)
TE
SG–1
B–R
6
IF1
IF1
4
G–Y
G–W
2
C10
C10
DI–820
–
DIAGNOSTICS
AIR CONDITIONING SYSTEM
LEXUS RX300 (RM785E)
DTC
B1413/13 Evaporator Temperature Sensor circuit
CIRCUIT DESCRIPTION
This sensor detects the temperature inside the cooling unit and sends the appropriate signals to the A/C ECU
(Combination meter ECU).
DTC No.
Detection Item
Trouble Area
B1413/13
Open or short in evaporator temperature sensor circuit.
S Evaporator temperature sensor.
S Harness or connector between evaporator temperature sen-
sor and A/C ECU (Combination meter ECU).
S A/C ECU (Combination meter ECU).
WIRING DIAGRAM
DI3FW–03
I08335
TE
SG–1
(+)
(–)
–
DIAGNOSTICS
AIR CONDITIONING SYSTEM
DI–821
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 form step 2.
1
Check evaporator temp. sensor using hand–held tester.
PREPARATION:
Connect the hand–held tester to the DLC3.
CHECK:
Check the evaporator temp. sensor using DATA LIST.
OK
Check and replace A/C ECU (Combination me-
ter ECU).
NG
2
Check voltage between terminals TE and SG–1 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 TE and SG–1 of A/C
ECU connector at each temperature.
OK:
Voltage :
at 0
°C (32°F) : 2.0 – 2.4 V
at 15
°C (59°F) : 1.4 – 1.8 V
HINT:
As the temperature increases, the voltage decreases.
NG
Go to step 3.
OK
Proceed to next circuit inspection shown on problem symptorms table (See page DI–812). How-
ever, if DTC B1413/13 is displayed, check and replace A/C ECU (Combination meter ECU).
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