TOYOTA SUPRA 1995 Service Repair Manual

TROUBLESHOOTING
The table below will be useful for you in troubleshooting these electrical problems. The most likely causes
of the malfunction are shown in the order of their probability. Inspect each part in the order shown, and
replace the part when it is found to be faulty.
 
 Trouble
 
 Parts name (See page)
 
 
 
Mirror does not operate
 
 
 
1. RAD No.2 Fuse (BE±6)
2. Mirror Switch (BE±79)
3. Mirror Motor (BE±80)
4. Wire Harness
 
 
 Mirror operates abnormally
 
 
 
1. Mirror Switch (BE±79)
2. Mirror Motor (BE±80)
3. Wire Harness
MIRROR SWITCH INSPECTION
INSPECT SWITCH CONTINUITY
Left Side
 
 Switch position
 
 
Tester connection to
terminal number 
 Specified condition
 OFF ± No continuity
 
 UP
 
 
2±5
6±8 
 Continuity
 
 DOWN
 
 
2±6
5±8 
 Continuity
 
 LEFT
 
 
1±8
2±5 
 Continuity
 
 RIGHT 
 
1±2
5±8 
 Continuity
Right Side 
 Switch position
 
 Tester connection to
terminal number 
 Specified condition
 OFF ± No continuity 
 UP
 
 2±5
3±8 
 Continuity
 
 DOWN
 
 2±3
5±8 
 Continuity
 
 LEFT
 
 2±5
7±8 
 Continuity
 
 RIGHT
 
 2±7
5±8 
 Continuity
If continuity is not as specified, replace the switch.
± BODY ELECTRICAL SYSTEMPOWER MIRROR CONTROL SYSTEMBE±79

MIRROR MOTOR INSPECTION
INSPECT MOTOR OPERATION
(a) Connect the positive (+) lead from the battery to terminal 3
and negative (±) lead to terminal 4, check that the mirror turns
upward.
(b) Reverse the polarity, check that the mirror turns to downward.
(c) Connect the positive (+) lead from the battery to terminal 5
and negative (±) lead to terminal 4, check that the mirror turns
to left side.
(d) Reverse the polarity, check that the mirror turns to right side.
If operation is not as specified, replace the mirror. BE±80
± BODY ELECTRICAL SYSTEMPOWER MIRROR CONTROL SYSTEM

Frequency 30 kHz 300kHz 3 MHz 30 MHz300 MHz
Designation
Modulation method
Radio wave
LF
AMFM
VHF
Amplitude modulation
HFMF
Frequency modulation
AUDIO SYSTEM
SYSTEM DESCRIPTION
1. RADIO WAVE BAND
The radio wave bands used in radio broadcasting are as follows:
LF: low Frequency MF: Medium Frequency HF: High Frequency VHF: Very High Frequency
2. SERVICE AREA
There are great differences in the size of the service area for
AM, FM monaural, and FM stereo broadcasts cannot be re-
ceived even though AM comes in very clearly.
Not only does FM stereo have the smallest service area, but
it also picks up static and other types of interference (ºnoiseº)
easily.
± BODY ELECTRICAL SYSTEMAUDIO SYSTEMBE±81

3. RECEPTION PROBLEMS
Besides the problem of static, there are also the problems
called ºfadingº, ºmultipathº and ºfade outº. These problems
are caused not by electrical noise but by the nature of the ra-
dio waves themselves.
Fading
Besides electrical interference, AM broadcasts are also sus-
ceptible to other types of interference, especially at night.
This is because AM radio waves bounce off the ionosphere
at night. These radio waves then interfere with the signals
from the same transmitter that reach the vehicle's antenna di-
rectly. This type of interference is called ºfadingº.
Multipath
One type of interference caused by the bouncing of radio
waves off of obstructions is called ºmultipathº. Multipath oc-
curs when a signal from the broadcast transmitter antenna
bounces off buildings and mountains and interferes with the
signal that is received directly.
Fade Out
Because FM radio waves are of higher frequencies than AM
radio waves, they bounce off buildings, mountains, and other
obstructions. For this reason, FM signals often seem to grad-
ually disappear or fade away as the vehicle goes behind a
building or other obstruction. This is called ºfade outº. BE±82
± BODY ELECTRICAL SYSTEMAUDIO SYSTEM

4. COMPACT DISC PLAYER
Compact Disc (hereafter called ºCDº) Players use a laser
beam pick±up to read the digital signals recorded on the CD
and reproduce analog signals of the music, etc. There are 4.7
in. (12 cm) and 3.2 in. (8 cm) discs in the CD player.
HINT: Never attempt to disassemble or oil any part of the
player unit. Do not insert any object other than a disc into the
magazine.
NOTICE: CD players use an invisible laser beam which
could cause hazardous radiation exposure. Be sure to
operate the player correctly as instructed.
MAINTENANCE
Tape Player/Head Cleaning
(a) Raise the cassette door with your finger.
Next using a pencil or similar object, push in the guide.
(b) Using a cleaning pen or cotton applicator soaked in cleaner,
clean the head surface, punch rollers and capstans.
CD Player/Disc Cleaning
If the disc gets dirty, clean the disc by wiping the surfaces
from the center to outside in the radial directions with a soft
cloth.
NOTICE: Do not use a conventional record cleaner or anti
±static preservative.
± BODY ELECTRICAL SYSTEMAUDIO SYSTEMBE±83

ANTI±THEFT SYSTEM
HINT: The words ºANTI±THEFT SYSTEMº are displayed on
the cassette tape slot cover.
For operation instructions for the anti±theft system, please
consult the audio system section in the Owner's Manual
(hereafter called O/M).
1. SETTING SYSTEM
The system is in operation once the customer has pushed the
required buttons and entered the customer±selected 3±digit
ID number.
(Refer to the O/M section, ºSetting the anti±theft systemº)
HINT:
w When the audio system is shipped the ID number has
not been input, so the anti±theft system is not in
operation.
w If the ID number has not been input, the audio system
remains the same as a normal audio system.
2. ANTI±THEFT SYSTEM OPERATION
If the normal electrical power source (connector or battery
terminal) is cut off, the audio system becomes inoperable,
even if the power supply resumes.
3. CANCELING SYSTEM
The ID number chosen by the customer is input to cancel the
anti±theft system.
(Refer to the O/M section, ºIf the system is activatedº)
HINT: To change or cancel the ID number, please refer to the
O/M section ºCancelling the systemº. BE±84
± BODY ELECTRICAL SYSTEMAUDIO SYSTEM

PARTS LOCATION
± BODY ELECTRICAL SYSTEMAUDIO SYSTEMBE±85

TROUBLESHOOTING
NOTICE: When replacing the internal mechanism (computer part) of the audio system, be careful
that no part of your body or clothing comes in contact with the terminals of the leads from the IC,
etc. of the replacement part (spare part).
HINT: This inspection procedure is a simple troubleshooting which should be carried out on the vehicle
during system operation and is based on the assumption that the cause of trouble lies with the system com-
ponents (except for the wires and connectors, etc.).
Always inspect the trouble taking the following items into consideration.
w Open or short circuit of the wire harness
w Connector or terminal connection fault
w Troubleshooting items marked *indicate that ºTroubleshooting for ANTI±THEFT SYSTEMº should be
carried out first.
 Problem No.  No power coming in. *1  Power coming in, but radio not operating. 2  Noise present, but AM±FM not operating. 3
  Either speaker does not work. 4
  Woofer speaker does not work. 5
 Radio Either AM or FM does not work. 6
  Reception poor (Volume faint). 6
  Few preset tuning bands. 6
  Sound quality poor. 7
  Cannot set station select button. 8
  Preset memory disappears. 8
  Cassette tape cannot be inserted. 9
Cassette tape inserts, but no power.*10  Power coming in, but tape player not operating. 11  Either speaker does not work. 12 Tape player Woofer speaker does not work. 13 y Sound quality poor (Volume faint). 14  Tape jammed, malfunction with tape speed or auto±reverse. 15  APS, SKIP, RPT buttons not operating. 16
  Cassette tape will not eject. *17
  CD cannot be inserted. 18
  CD inserts, but no power. 19
  Power coming in, but CD player not operating. 20
 CDplayer Sound jumps. 21
 CD player Sound quality poor (Volume faint). 22
  Either speaker does not work. 23
  Woofer speaker does not work. 24
  CD will not eject. 25
No power coming in.26 
Amplifier
 Power coming in, but woofer amplifier (Power amplifier) not operating. 27 Amplifier Either speaker does not work. 28  Woofer speaker does not work. 29
BE±86± BODY ELECTRICAL SYSTEMAUDIO SYSTEM

 Problem No.
 Noise Noise produced by vibration or shock while driving. 30
  Noise produced when engine starts. 31
 Antenna Antenna±related. 32
 ANTI±THEFT SYSTEM Troubleshooting for ANTI±THEFT SYSTEM 33
HOW TO USE DIAGNOSTIC CHART
Is tape player operating
Is ACC applied to radio?Tape player faulty.
Check if GND (wire harness side)
to radio is OK.
Radio faulty.Radio assembly faulty.
Check if CIG & RAD fuse is OK.Replace fuse.
Is ACC applied to radio?
Is ACC applied to tape player?
Is ACC applied to power amplifier?
ACC wire harness faulty?
NO POWER COMING INRadio
(1) Audio system type and symbol used.
HINT: Confirm the applicable type of audio system.
(2) Symbol for type of audio system the question applies to.
HINT: If the audio system type is not applicable, proceed to next question below.
(3) Junction without black circle.
HINT: Proceed to next question below.
(4) Junction with black circle.
HINT: Proceed to question for applicable audio system type.
(5) HINT: Select question for applicable audio system type.
± BODY ELECTRICAL SYSTEMAUDIO SYSTEMBE±87

1 Radio NO POWER COMING IN
Is tape player operating normally?
Is ACC applied to power amplifier?
Replace fuse.Check if RAD No. 2 fuse is OK?
Power amplifier faulty.
GND faulty.
Power amplifier faulty.
ACC wire harness faulty.Is ACC applied to radio assembly?
GND faulty.
ACC wire harness faulty.
Check if GND (wire harness side) to
radio is OK?
Radio assembly faulty.
Radio assembly faulty.
Check if GND (wire harness side)
to power amplifier is OK?
BE±88± BODY ELECTRICAL SYSTEMAUDIO SYSTEM