light LEXUS SC400 1991 Service Repair Manual

TROUBLE SHOOTING:
Use the matrix chart below as a guide to repairs. Verify necessary inputs to the A/C Control Assembly from
the vehicle prior to disassembly. Use the repair manual, A/C system section, to validate such as B+, IL\
L+,
ground, etc.. SUSPECT AREA
SYMPTOM Control Switch Indicator Panel Control Lamp Circuit
Night Illumination does not come on
LCD back lighting does not come on
Indicator lamps of all switches are off
Indicator lamp of all switches are on
LCD is faulty
NOTE: If symptoms still exist after the suspect areas have been tested and fou\
nd not to be
faulty, replace the amplifier.
1LCD illumination bulbs are not serviceable, Control Switch must be repla\
ced if illumination
does not occur.
AIR CONDITIONING CONTROL DISASSEMBLY
:
1. Remove Air Conditioning Control Assembly.
2. Separate Control Panel from case. a. Cut the cloth tape on both sides of the case (See Fig. 2).
1992 - 1995 SC 300/400 A/C CONTROL ASSEMBLY SERVICE PARTS Page 2 of 6
Bulb Switch


1




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SENSOR INSPECTION FOR AIR CONDITIONING SYSTEM ± AC005-04 December 16, 2004
Page 2 of 12
1. Inspect Room Temperature Sensor.
A. Measure the sensor resistance.
Resistance Value at 77 5F
(25 5C)1700 +/± 85 W
NOTE:
Even slightly touching the sensor
may change the resistance value.
Be sure to hold the connector of
the sensor.
When measuring, the sensor
temperature must be the same as
the ambient temperature.
HINT:
As the temperature increases, the
resistance decreases.
TEMPERATURE 5F ( 5C)SPECIFICATION k W
50 (10)3.00 to 3.73
59 (15)2.45 to 2.88
68 (20)1.95 to 2.30
77 (25)1.60 to 1.80
86 (30)1.28 to 1.47
95 (35)1.00 to 1.22
104 (40)0.80 to 1.00
113 (45)0.65 to 0.85
122 (50)0.50 to 0.70
131 (55)0.44 to 0.60
140 (60)0.36 to 0.50
Inspection
Procedure
Resistance
k W
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
32
(0) 68
(20) 104
(40) 140
(60)
Temperature 5F ( 5C)
Max
Min
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SENSOR INSPECTION FOR AIR CONDITIONING SYSTEM ± AC005-04 December 16, 2004
Page 3 of 12
2. Inspect Ambient
Temperature Sensor.
A. Measure the sensor resistance according to the selected graph
(specification).
Resistance Value at 77 5F
(25 5C)1700 +/± 85 W
NOTE:
Even slightly touching the sensor
may change the resistance value.
Be sure to hold the connector of
the sensor.
When measuring, the sensor
temperature must be the same as
the ambient temperature.
HINT:
As the temperature increases, the
resistance decreases.
TEMPERATURE 5F ( 5C)SPECIFICATION k W
50 (10)3.00 to 3.73
59 (15)2.45 to 2.88
68 (20)1.95 to 2.30
77 (25)1.60 to 1.80
86 (30)1.28 to 1.47
95 (35)1.00 to 1.22
104 (40)0.80 to 1.00
113 (45)0.65 to 0.85
122 (50)0.50 to 0.70
131 (55)0.44 to 0.60
140 (60)0.36 to 0.50
Inspection
Procedure
(Continued)
Resistance
k W
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
32
(0) 68
(20) 104
(40) 140
(60)
Temperature 5F ( 5C)
Max
Min
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SENSOR INSPECTION FOR AIR CONDITIONING SYSTEM ± AC005-04 December 16, 2004
Page 4 of 12
3. Inspect Air Duct Sensor.
A. Measure the sensor resistanceaccording to the table and
graph (specification).
NOTE:
Even slightly touching the sensor
may change the resistance value.
Be sure to hold the connector of
the sensor.
When measuring, the sensor
temperature must be the same as
the ambient temperature.
HINT:
As the temperature increases, the
resistance decreases.
TEMPERATURE 5F ( 5C)SPECIFICATION k W
50 (10)9.48 to 10.49
59 (15)7.50 to 8.28
68 (20)5.95 to 6.57
77 (25)4.77 to 5.25
86 (30)3.85 to 4.21
95 (35)3.12 to 3.40
104 (40)2.53 to 2.79
113 (45)2.06 to 2.30
122 (50)1.69 to 1.91
131 (55)1.39 to 1.59
140 (60)1.15 to 1.33
Inspection
Procedure
(Continued)
Resistance
k W
15.0
10.0
5.0
0.0 32
(0) 68
(20) 104
(40) 140
(60)
Temperature 5F ( 5C)
Max
Min 176
(80)
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SENSOR INSPECTION FOR AIR CONDITIONING SYSTEM ± AC005-04 December 16, 2004
Page 6 of 12
A. Measure the sensor resistance according to the selected graph (specification)\
.
NOTE:
Even slightly touching the sensor may change the resistance value.
Be sure to hold the connector of the sensor.
When measuring, the sensor temperature must be the same as the
ambient temperature.
HINT:
As the temperature increases, the resistance decreases.
Graph 1:
TEMPERATURE 5F ( 5C)SPECIFICATION k W
14 (±10)7.30 to 9.10
23 (±5)5.65 to 6.95
32 (0)4.40 to 5.35
41 (5)3.40 to 4.15
50 (10)2.70 to 3.25
59 (15)2.14 to 2.58
68 (20)1.71 to 2.05
77 (25)1.38 to 1.64
86 (30)1.11 to 1.32
Graph 2:
TEMPERATURE 5F ( 5C)SPECIFICATION k W
14 (±10)7.40 to 9.20
23 (±5)5.65 to 7.00
32 (0)4.35 to 5.40
41 (5)3.40 to 4.20
50 (10)2.68 to 3.30
59 (15)2.10 to 2.60
68 (20)1.66 to 2.10
77 (25)1.32 to 1.66
86 (30)1.05 to 1.35
Inspection
Procedure
(Continued)
Resistance
k W
12.0
3.0
2.0
0.0 32
(0) 68
(20) 104
(40)
Temperature 5F ( 5C)
Max
Min
1.0 4.0 8.0
7.0
5.0 6.0 9.0
10.0 11.0
±4
(±20)
32
(0) 68
(20) 104
(40)
±4
(±20)
Resistance
k W
3.0
2.0
0.0 Temperature 5F ( 5C)
Max
Min
1.0 4.0 8.0
7.0
5.0 6.0 9.0
10.0
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SENSOR INSPECTION FOR AIR CONDITIONING SYSTEM ± AC005-04 December 16, 2004
Page 8 of 12
5. Inspect Solar Sensor.
Four types of solar sensors are used on Lexus vehicles depending on the \
vehicle
specifications. The inspection procedure for each type of sensor differs from the
others. Select the appropriate inspection procedure from the table below\
according to
vehicle specifications and perform the inspection.
EQUIPPED WITH AUTOMATICLIGHT CONTROL SYSTEMA/C SYSTEM WITH RIGHT/LEFT
INDEPENDENT TEMPERATURE CONTROLINSPECTION
PROCEDURE
NoNoA
NoYesB
YesYesC
YesNoD
Procedure A:
a. Disconnect the solar sensor connector.
b. Measure the resistance between terminals 1 and 2 of the solar
sensor under the
following conditions:
Cover the sensor with a cloth
to avoid direct light.
Expose the sensor to light
from a distance of 300 mm
(11.81 in.) or less with an
inspection light.
NOTE:
Terminal 1 of the sensor is always on
the right, when the lock is facing up.
When using an analog tester, connect
the positive (+) lead to terminal 2 and
negative (±) lead to terminal 1 of the
solar sensor.
HINT:
If the light is weak, the sensor may not react. Be sure to use an incand\
escent light for
an inspection light.
Standard:
CONDITIONSPECIFICATION
When the sensor is covered with a cloth
(to avoid direct light)Infinite ohms
When the sensor is exposed to lightLess than infinite resistance
InspectionProcedure
(Continued)
Lock
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SENSOR INSPECTION FOR AIR CONDITIONING SYSTEM ± AC005-04 December 16, 2004
Page 9 of 12
Procedure B:
a. Disconnect the solar sensor connector.
b. Measure the resistance between terminals 2 and 3 of the solar
sensor under the
following conditions:
Cover the sensor with a cloth
to avoid direct light.
Expose the sensor to light
from a distance of 300 mm
(11.81 in.) or less with an
inspection light.
NOTE:
When using an analog tester, connect
the positive (+) lead to terminal 3 and
negative (±) lead to terminal 2 of the
solar sensor.
HINT:
If the light is weak, the sensor may not react. Be sure to use an incand\
escent light for
an inspection light.
Standard:
CONDITIONSPECIFICATION
When the sensor is covered with a cloth
(to avoid direct light)Infinite ohms
When the sensor is exposed to lightLess than infinite resistance
InspectionProcedure
(Continued)
Lock
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SENSOR INSPECTION FOR AIR CONDITIONING SYSTEM ± AC005-04 December 16, 2004
Page 10 of 12
Procedure C:
a. Turn the ignition switch ON.
b. Measure the voltage between terminals TSR (+) and CLTE (±)
of the connector under the
following conditions:
Cover the sensor with a cloth
to avoid direct light.
Expose the sensor to light
from a distance of 300 mm
(11.81 in.) or less with an
inspection light.
HINT:
If the light is weak, the sensor may not react. Be sure to use an incandes\
cent light
for an inspection light.
Do not disconnect the solar sensor connector.
Standard:
CONDITIONSPECIFICATION
When the sensor is covered with a cloth
(to avoid direct light)Below 0.8 V
When the sensor is exposed to light4.3 +/± 0.3 V
c. Measure the voltage between
terminals TSL (+) and CLTE (±)
of the connector under the
following conditions:
Cover the sensor with a cloth
to avoid direct light.
Expose the sensor to light
from a distance of 300 mm
(11.81 in.) or less with an
inspection light.
HINT:
If the light is weak, the sensor may not react. Be sure to use an incand\
escent light
for an inspection light.
Do not disconnect the solar sensor connector.
Standard:
CONDITIONSPECIFICATION
When the sensor is covered with a cloth
(to avoid direct light)Below 0.8 V
When the sensor is exposed to light4.3 +/± 0.3 V
InspectionProcedure
(Continued)
CLTE
TSR
TSL
CLTE
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SENSOR INSPECTION FOR AIR CONDITIONING SYSTEM ± AC005-04 December 16, 2004
Page 11 of 12
Procedure D:
a. Turn the ignition switch ON.
b. Using the tester, measure the voltage between terminals
TSD (+) and CLTE (±) of the
connector under the
following conditions:
Cover the sensor with a cloth
to avoid direct light.
Expose the sensor to light
from a distance of 300 mm
(11.81 in.) or less with an
inspection light.
HINT:
If the light is weak, the sensor may not react. Be sure to use an incandes\
cent light
for an inspection light.
Do not disconnect the solar sensor connector.
Standard:
CONDITIONSPECIFICATION
When the sensor is covered with a cloth
(to avoid direct light)Below 0.8 V
When the sensor is exposed to light4.3 +/± 0.3 V
InspectionProcedure
(Continued)
TSD
CLTE
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Some SC 300/SC 400 vehicles may have a sunvisor which falls away slightly from the roof
when placed in the full upright position. To improve visor retention, the position of an internal
clip has been modified in production.
BODY
BO92±004
APRIL 24, 1992
SC 300/SC 400
PART NUMBER INFORMATION:
New Part NumberPrev. Part NumberDescriptionSide
NOTE:Before replacing the Sunvisor assembly, ensure that shaft is fully seated into the
sunvisor by pushing the sunvisor further onto the shaft. This may
seat the internal clip into
the groove on the shaft.
PRODUCTION EFFECTIVE:
FROM: November, 1991
VIN: SC 400: JT8UZ30C9N0011202
SC 300: JT8JZ30C9N0002890
Same
º
º
Same
º
º
Same
º
º
Same
º
º Medium Gray
SpruceIvory
SC 300/SC 400 IMPROVED SUNVISOR HINGE RETENTION (REVISED) Page 1 of 1
Medium Gray
SpruceIvory
Medium Gray SpruceIvory
Medium Gray SpruceIvory RH
RH
RH
RH w/Sunroof
RH w/Sunroof
RH w/Sunroof LH
LH
LH
LH w/Sunroof
LH w/Sunroof
LH w/Sunroof
74310±24120±03
74310±24120±07
74310±24120±08
74310±24130±03
74310±24130±07
74310±24130±08
74320±24130±03
74320±24130±07
74320±24130±08
74320±24080±03
74320±24080±07
74320±24080±08
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