1991 LEXUS SC400 relay

2. INSPECT ANTENNA MOTOR
(a) Install antenna nut.
(b) Disconnect connector from the motor antenna control relay.
(c) Connect the positive (+) lead from the battery to terminal 2and the negative (±) lead to terminal 5 on the wire harness
side connector.
(d) Check that the motor turns (moves upward).
NOTICE: These tests must be performed quickly (within 4±8
seconds) to prevent the coil from burning out.
(e) Then, reverse the polarity, check that the motor turns the opposite way (moves downward).
NOTICE: These tests must be performed quickly (within 4±8
seconds) to prevent the coil from burning out.
HINT: When the motor is normal, lower the antenna to the
lower most position.
If operation is not as specified, replace the antenna motor as-
sembly.
GLASS PRINTED ANTENNA
GLASS PRINTED ANTENNA
INSPECTION
1. INSPECT GLASS PRINTED ANTENNA(Use same procedure as for ºINSPECT DEFOGGER
WIRESº on page BE±173.)
2. REPAIR GLASS PRINTED ANTENNA (Use same procedure as for ºREPAIR DEFOGGER WIRESº
on page BE±174.)
BE±216
±
BODY ELECTRICAL SYSTEM AUDIO SYSTEM
WhereEverybodyKnowsYourName

32AntennaANTENNA±RELATED
Does antenna extend when radio switched ON?Wire harness faulty.
Is there battery voltage between the following
terminals with connector disconnected?


Motor antenna control relay 6 ± ground

Motor antenna control relay 14 ± ground

Motor antenna control relay 3 ± ground
Wire harness faulty.Replace fuses.
Radio receiver assembly faulty.
Check if ECU±IG, RADIO No. 1 and RADIO No.
2 fuse are OK.
ªAMº button turned ON.
Is there battery voltage between the following
terminals with connector connected?

Radio receiver assembly A9 (*A1) ± ground

Radio receiver assembly A8 ± ground

Radio receiver assembly D4 ± ground

Radio receiver assembly D10 ± ground Radio receiver side
faulty.
Motor antenna faulty.
Temporarily install another motor antenna is
radio operating normally?
Glass printed antenna faulty.
Check if glass printed antenna is OK.
Is there continuity between the following terminals
with connector disconnected?

Motor antenna control relay 4 ± ground
Continued on next page.
BE±260±
BODY ELECTRICAL SYSTEM AUDIO SYSTEM
WhereEverybodyKnowsYourName

Wire harness faulty.
Is there continuity between the following terminals
with connector disconnected?

Radio receiver assembly A9 (*A1) ± Motor anten-
na control relay 4

Radio receiver assembly A8 ± Motor antenna
control relay 5

Radio receiver assembly D4 ± Motor antenna
control relay 2

Radio receiver assembly D10 ± Motor antenna
control relay 12
Temporarily install another motor antenna con-
trol relay. Functions OK? Motor antenna control relay faulty.
Motor antenna control relay faulty.
±
BODY ELECTRICAL SYSTEM AUDIO SYSTEMBE±261
WhereEverybodyKnowsYourName

HORN RELAY
HORN RELAY INSPECTION
INSPECT RELAY CONTINUITY AND OPERATION
If operation is not as specified, replace the relay.
Troubleshooting
You will find the cause of trouble more easily by properly using the tabl\
e shown below. In this table, the
numbers indicate the order of priority of the causes of trouble. Check each part in \
the order shown. If neces-
sary, replace these part.
See page
BE±4 , 21BE±264BE±263BE±263
±
Trouble
Parts
name
HAZ±HORN FuseHorn SwitchHorn SwitchHornWire Harness
\
\
Horn system does not operate 1 2 3 4 5\


\
Horns blow all the time
 


 

1
 

2
 


 

3
\


\
One horn operates but other horn does not
Operate 


 


 


 


1 


2
\
\
Horns operate abnormally  1  2 3
BE±264±
BODY ELECTRICAL SYSTEM HORN SYSTEM
WhereEverybodyKnowsYourName

DESCRIPTION
The Power Seat Control System carries out seat slide, front vertical, rear \
vertical, reclining and lumbar support
position adjustments electrically. Power seat switch and lumbar support switch.
In addition, operation of the memory switch makes it possible to store the positions of the slide, front vertical,
rear vertical and reclining adjustments in memory and return to the posi\
tion.
The component parts of this system and their function are described in t\
he following table.
 Parts Name\
 \
Function
 








Driver's Seat ECU
\
 
\


\


\


\

\

The seat ECU controls power operation, memory operation, and position re\
turn
operation of the power seat. When input is received from the power seat \
switch,
the relay inside the ECU is controlled and the power seat operates. The \
seat
memory and position return are controlled by mutual communication betwee\
n the
electrically operated Tilt and Telescopic ECU and the seat ECU.
 

Power Seat Switch\
 
\

\

Operation of this switch sends slide, front vertical, rear vertical, rec\
lining signals
to ECU.
 




Driving Position
Memory and Return
Switch\
 
\


\

\

Memory and Return Signals are sent to the seat ECU via the Tilt and Telescopic
ECU.
 






Lumbar Support
Switch
\
 
\


\


\

\

This switch is supplied with power from the DOOR fuse. When the switch i\
s
operated, power is supplied to the lumbar support motor controlling the \
direction
in which the motor turns and turning the current ON and OFF. This switch is not
connected to the ECU and the adjustment position cannot be stored in mem\
ory
for return operation.
 

Position Sensor
\
 
\

\
This sensor sends signals on the position of each motor (slide, front v\
ertical, rear
vertical and reclining) to the ECU for use in memory and return.
 

*Motor
\
 
\

\

These motors operate on current from the driver's seat ECU moving the various
parts of the seat directly. Each motor has a built±in circuit breaker.
*: Slide, Front Vertical, Rear Vertical, Lumbar Support and Reclining.
Motors contained in each seat are described in the following table.
 Motor Slide Front
Vertical
 Rear
Vertical
 Reclining Lumbar
Support 

Seat 

Motor 


Vertical
Motor
 


Vertical
Motor
 


g
Motor 


Support
Motor
 Driver's Seat O* O* O* O* O
*: Operated by the memory and return functions. BE±266
±
BODY ELECTRICAL SYSTEM Power Seat Control System (Driver's Seat)
WhereEverybodyKnowsYourName

Replacement of Fuse
HINT: If replacing the fuse, be sure to replace it with a fuse
with an equal amperage rating.
NOTICE:
1. Turn off all electrical components and the ignition switchbefore replacing a fuse. Do not exceed the fuse amperage
rating.
2. Always use a fuse puller for removing and inserting a fuse. Remove and insert straight in and out without
twisting. Twisting could force open the terminals too
much, resulting in a bad connection.
If a fuse continues to blow, a short circuit is indicated. The
system must be checked by a qualified technician.
HINT: The puller is located at Relay Block No. 2.
How to Inspect for System Inspection
This inspection precedure is a simple troubleshooting which
should be carried out on the vehicle during system operation
and is based on the assumption of system component
trouble (except for the wires and connectors, etc.).
Always inspect the trouble taking the following items into con-
sideration.
wGround point fault
w Open or short circuit of the wire harness
w Connector or terminal connection fault
w Fuse or fusible link fault
NOTICE:
1. This is an on±vehicle inspection during system
operation. Therefore, inspect the trouble with due regard
for safety.
2. If connecting the battery directly, be careful not to short circuit, and select the applicable voltage.
BE±4±
BODY ELECTRICAL SYSTEM General Information
WhereEverybodyKnowsYourName

Check for Voltage
(a) Establish conditions in which voltage is present at thecheck point.
Example:
(A)±Ignition SW on
(B)±Ignition SW and SW 1 on
(C)±Ignition SW, SW 1 and Relay on (SW 2 off)
(b) Using a voltmeter, connect the negative (±) lead to a good ground point or negative (±) battery terminal and
the positive (+) lead to the connector or component
terminal. This check can be done with a test bulb instead
of a voltmeter.
Check for Continuity and Resistance
(a) Disconnect the battery terminal or wire so there is no voltage between the check points.
(b) Connect the two leads of an ohmmeter to each of the check points.
If the circuit has diodes, reverse the two leads and check
again.
When contacting the negative (±) lead to the diode positive
(+) side and the positive (+) lead to the negative (±) side,
there should be continuity. When contacting the two leads in
reverse, there should be no continuity.
HINT: Specifications may vary depending on the type of tes-
ter, so refer to the tester's instruction manual before perform-
ing the inspection.
Check LED (Light Emitting Diode) in the same manner as that
for diodes.
HINT:
w Use a tester with a power source of 3 V or greater to
overcome the circuit resistance.
w If a suitable tester is not available, apply battery voltage
and check that the LED lights up.
±
BODY ELECTRICAL SYSTEM General InformationBE±5
WhereEverybodyKnowsYourName

(c) Use a volt/ohmmeter with high impedance (10 k/Vminimum) for troubleshooting of the electrical circuit.
Check the Bulb
(a) Remove the bulb.
(b) There s hould be continuity between the respective
terminals of the bulb together with a certain amount of
resistance.
(c) Apply the two leads of the ohmmeter to each of the terminals.
(d) Apply battery voltage and check that the bulb light up.
Check for Short Circuit
(a) Remove the blown fuse and eliminate all loads from the fuse.
(b) Connect a test bulb in place of the fuse.
(c) Establish conditions in which the test bulb comes on.
Example:
(A)±Ignition SW on
(B)±Ignition SW and SW 1 on
(C)±Ignition SW, SW 1 and Relay on (Connect the Relay) and
SW 2 off (or Disconnect SW 2)
(d) D i s c onnect 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.
BE±6
±
BODY ELECTRICAL SYSTEM General Information
WhereEverybodyKnowsYourName