bulb LEXUS SC400 1991 Service Owner's Guide

1. REMOVE COVER(a) Remove the seven screws.
(b) Remove the cover from the meter case.
2. REMOVE METER GLASS (a) Remove the twelve screws.
(b) Remove the character plate from the meter plate.
3. REMOVE METER PLATE (a) Remove the four screws.
(b) Remove the meter plate from the meter case.
4. REMOVE METER CIRCUIT PLATE (a) Remove the sixteen screws.
(b) Disconnect the two connectors from the meter circuit plate.
(c) Remove bulbs from the meter circuit plate.
(d) Remove the meter circuit plate.
5. REMOVE ODOMETER/TRIP METER Remove the two screws and the odometer/trip meter.
±
BODY ELECTRICAL SYSTEM Combination MeterBE±105
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OKNG
OKNG
INSPECTION PROCEDURE
1Check ABS warning light.
See Combination Meter Troubleshooting on page BE±159.
Replace bulb or combination meter assembly.
2Check ABS solenoid relay.
C
OK
P
OK
C
Remove solenoid relay from R/B No. 6.
Check continuity between each terminal of ABS sole-
noid relay shown below.
1. Apply battery voltage between terminals 4 and 6.
2. Check continuity between each terminal of ABS so-
lenoid relay shown below.
Replace ABS solenoid relay.
Repair or replace and check for open in harness and connector between ch\
eck connector and ABS
solenoid relay and body ground (See page IN±33).
BR±146±
BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)
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Wiring and Connector Diagrams
Parts Inspection
(Defogger Switch)
REMOVAL AND INSTALLATION OF AIR
CONDITIONER CONTROL PANEL
ASSEMBLY
(See Instrument Panel on Pub. No. RM260U2, page BO±111)
INSPECTION OF DEFOGGER SWITCH
INSPECT SWITCH OPERATION
(a) Connect the positive (+) lead from the battery to terminal A6and negative (±) lead to terminal A7.
(b) Connect the positive (+) lead from the battery to terminal B10
through a 1.4 W test bulb.
BE±52
±
BODY ELECTRICAL SYSTEM Defogger System
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(c) Turn the defogger switch ON and check that the test bulb andindicator light turn ON, then turn OFF after about 15 minutes.
If operation is not as specified, replace the air conditioner control
panel assembly.
(Defogger Relay)
INSPECTION OF DEFOGGER RELAY
INSPECT RELAY CONTINUITY AND OPERATION
If continuity is not as specified, replace the relay.
(Defogger Wires)
INSPECTION AND REPAIR OF
DEFOGGER WIRES
1. INSPECT DEFOGGER WIRESNOTICE:
w When cleaning the glass, use a soft, dry cloth, and wipe
the glass in the direction of the wire. Take care not to
damage the wires.
w Do not use detergents or glass cleaners with abrasive
ingredients.
w When measuring voltage, wind a piece of tin foil around
the top of the negative probe and press the foil against
the wire with your finger as shown.
(a) Turn the ignition switch ON.
(b) Turn the defogger switch ON.
(c) Inspect the voltage at the center of each heat wire as
shown.
 Voltage Criteria
Approx. 5 VOkay (No break in wire) Approx. 10 V or 0 V Broken wire
HINT: If there is approximately 10 volts, the wire is broken be-
tween the center of the wire and the positive (+) end. If there
is no voltage, the wire is broken between the center of the
wire and ground.
±
BODY ELECTRICAL SYSTEM Defogger SystemBE±53
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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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1992 - 1995 SC 300/400 A/C CONTROL ASSEMBLY SERVICE PARTSPage 3 of 6
AIR CONDITIONING CONTROL DISASSEMBLY (Cont'd):
b. Remove 2 screws and release the 6 clips to separate the Control Panel from the case.
c. Disconnect 2 connectors to separate the Control Panel from the case.
d. Remove the wire harness (See Fig. 5).
3. Remove Control Switch. a. To replace the Control Switch remove 2 screws and release 4 clips (See Fig. 6).
b. Separate Control Switch from face plate.
4. Replace the Night Illumination Bulb. Using a flat±bladed screwdriver, remove and
replace the Night Illumination Bulb.
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1992 - 1995 SC 300/400 A/C CONTROL ASSEMBLY SERVICE PARTSPage 4 of 6
INSPECTION PROCEDURE:
1. Bulb Circuit:
Bulb Inspection ± Perform the following test
on suspect Night Illumination Bulbs. Check
for continuity as shown. Replace the bulb if
there is no continuity.

Bulb Circuit Inspection ± Verify continuity
between terminals 22 and 24. If there is
no continuity, replace Control Switch.
2. Switch Circuit:
Switch Continuity Inspection ± Check that there
is continuity between the terminals while the
switch is pressed.
If there is no continuity between even one pair
of terminals, replace the Control Switch.
SWITCH
A/C
MODE/R>
MODE/L<
REAR - DEF
FRONT - DEF FRESH
RECIRC OFF
FAN - DOWN FAN - UP 13 - 17
13 - 16
13 - 15
12 - 17
12 - 16
12 - 15
12 - 14
11 - 17
11 - 16
11 - 15
INSPECTION
TERMINALS
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1992 - 1995 SC 300/400 A/C CONTROL ASSEMBLY SERVICE PARTSPage 6 of 6
MODEL
YEAR
Control Panel
Control Switch
Bulb
PART NUMBER INFORMATION:
PART NAME PART NUMBER MODEL APPLICATION QTY 55902-24010 `92-`94 SC 300/SC 400 1
55902-24020 `95 SC 300/SC 400 1
88601-24020 `92-`94 SC 300/SC 400 1
88601-24030 `95 SC 300/SC 400 1
84999-60360 `92-`94 SC 300/SC 400 3
84999-60340 `95 SC 300/SC 400 3
88650-24150 `92 SC 300 1
88650-24160 `92 SC 400 1
Amplifier with Case 88650-24190 `93-`94 SC 300 1
88650-24200 `93-`94 SC 400 1
88650-24231 `95 SC 300/SC 400 1
Wire Harness 88484-24010 `92-`95 SC 300/SC 400 1
Screws 90094-90416 `92-`95 SC 300/SC 400 *
* Screw Replacement not required for repair
WARRANTY INFORMATION
:
OPCODE DESCRIPTION TIME* OPN T1 T2
883851 A/C Control Assy, R&R 0.6 55900-XXXXX ** **
Combo ªAº Control Panel R&R 0.2 22902-XXXXX ** **
Combo ªCº Bulbs R&R 0.2 84999-XXXXX ** **
Combo ªDº Amplifier with Case R&R 0.2 88650-XXXXX ** ** Combo ªEº Wire Harness R&R 0.2 88484-XXXXX ** **
Combo ªGº Control Switch R&R 0.2 88601-XXXXX ** **
* Listed time for sub±operations are to be added to base operation to R\
&R the A/C control Assembly and include all necessary checks and tests.
** As applicable per the Lexus Universal Flat Rate Manual.
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11
FINDING A SHORT CIRCUIT
(a) Remove the blown fuse and disconnect all loads of thefuse.
(b) Connect a test bulb in place of the fuse.
(c) Establish conditions in which the test bulb comes on.
Example: ± Ignition SW on
± Ignition SW and SW 1 on
± Ignition SW, SW 1 and Relay on (Connect theRelay) and SW 2 off (or Disconnect SW 2)
(d) Disconnect and reconnect the connectors while watching the test bulb.
The short lies between the connector where the test
bulb stays lit and the connector where the bulb goes
out.
(e) Find the exact location of the short by lightly shaking the problem wire along the body.
CAUTION:
(a) Do not open the cover or the case of the ECU unlessabsolutely necessary. (If the IC terminals are touched,
the IC may be destroyed by static electricity.)
(b) When replacing the internal mechanism (ECU part) of the digital meter, be careful that no part of your body or
clothing comes in contact with the terminals of leads
from the IC, etc. of the replacement part (spare part).
DISCONNECTION OF MALE AND FEMALE
CONNECTORS
To pull apart the connectors, pull on the connector itself, not the
wire harness.
HINT: Check to see what kind of connector you are disconnecting
before pulling apart.
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