1995 TOYOTA SUPRA ignition

Theft Deterrent Horn Circuit
CIRCUIT DESCRIPTION
When the theft deterrent system is activated, contact (a) and contact (b) in the ECU close alternately in cycles
of approximately 0.2 sec., causing the theft deterrent horn to blow (See the wiring diagram below).
In this condition, if any of the following operations is done, the contact (a) in the ECU opens, thus stopping the
theft deterrent horn from blowing:
(1) The front LH or RH door is unlocked with a key.
(2) The ignition switch is turned to ACC or ON position.
(3) Approximately 1 minute elapses.
BE±134± BODY ELECTRICAL SYSTEM
THEFT DETERRENT AND DOOR LOCK CONTROL SYSTEM

Headlight Control Relay Circuit
CIRCUIT DESCRIPTION
When the theft deterrent system is activated, it causes the Tr in the ECU to switch on and off at approximately
0.2 sec. intervals. This switches the headlight control relay on and off, thus flashing the headlights (See the wir-
ing diagram below).
In this condition, if any of the following operations is done, the Tr in the ECU goes off and the headlight control
relay switches off, thus stopping the headlights flashing:
(1) The front LH or RH door is unlocked with a key.
(2) The ignition switch is turned to ACC or ON position.
(3) Approximately 1 minute elapses.
BE±136± BODY ELECTRICAL SYSTEMTHEFT DETERRENT AND DOOR LOCK CONTROL SYSTEM

Taillight Control Relay Circuit
CIRCUIT DESCRIPTION
When the theft deterrent system is activated, it causes the Tr in the ECU to switch on and off at approximately
0.2 sec. intervals. This switches the taillight control relay on and off, thus flashing the taillights (See the wiring
diagram below).
In this condition, if any of the following operations is done, the Tr in the ECU goes off and the taillight control
relay switches off, thus stopping the taillights flashing:
(1) The front LH or RH door is unlocked with a key.
(2) The ignition switch is turned to ACC or ON position.
(3) Approximately 1 minute elapses.
BE±138± BODY ELECTRICAL SYSTEMTHEFT DETERRENT AND DOOR LOCK CONTROL SYSTEM

Ignition Switch Circuit
CIRCUIT DESCRIPTION
When the ignition switch is turned to the ACC position, battery positive voltage is applied to the terminal ACC
of the ECU. Also, if the ignition switch is turned to the ON position, battery voltage is applied to the terminals
ACC and IG of the ECU. When the battery positive voltage is applied to the terminal ACC of the ECU while the
theft deterrent system is activated, the warning stops. Furthermore, power supplied from the terminals ACC and
IG of the ECU is used as power for the door courtesy switch, and position switch, etc.
BE±140± BODY ELECTRICAL SYSTEMTHEFT DETERRENT AND DOOR LOCK CONTROL SYSTEM

(See page IN±30).
Check for short in all the harness and
components connected to the CIG and ECU±IG
fuses (See attached wiring diagram).
(1) Remove instrument panel.
(See BO section)
(2) Disconnect the ECU connector.
(3) Turn ignition switch ON.
Check and replace theft deterrent and door lock
ECU.
Measure voltage between terminal IG and ACC of
theft deterrent ECU connector and body ground.
Voltage: 10 ± 14 V
Check and repair harness and connector between theft deterrent and door lock ECU and battery
(See page IN±30).
Check voltage between terminals IG and ACC of theft deterrent and door
lock ECU and body ground.
Continuity
Remove CIG and ECU±IG fuses from J/B NO. 1.
Check continuity of CIG and ECU±IG fuses.
Check CIG and ECU±IG fuses.
INSPECTION PROCEDURE
± BODY ELECTRICAL SYSTEMBE±141
THEFT DETERRENT AND DOOR LOCK CONTROL SYSTEM

(See page IN±30).
(1) Remove deck trim rear cover.
(2) Turn ignition switch ON.
Repair or replace luggage compartment door
key lock and unlock switch.
Measure voltage between terminal 1 of luggage
compartment door key lock and unlock switch
connector and body ground, when the key si
turned to the unlock side and not turned.
Check and replace theft deterrent and door lock
ECU. *1.
Check harness and connector between theft deterrent and door lock ECU and
key unlock switch, key unlock switch and body ground (See page
IN±30).
Check voltage between terminal 1 of luggage compartment door key lock
and unlock switch connector and body ground.
Key operation
Turned to the unlock side.
Not turned
Voltage
0 V
Battery positive voltage
Check luggage compartment door key lock and unlock switch.
Key operation
Turned to the unlock side.
Not turned
Disconnect luggage compartment door key lock and
unlock switch connector.
Check continuity between terminals 1 and 2, when
the key si turned to the unlock side and not turned.
Continuity
12
Repair or replace harness or connector.
Check and replace theft deterrent
and door lock ECU.
INSPECTION PROCEDURE
*1: When there is a malfunction that the theft deterrent
system cannot be set, proceed to the next
numbered circuit inspection shown on the
matrix chart (See page Be±123).
± BODY ELECTRICAL SYSTEMBE±143THEFT DETERRENT AND DOOR LOCK CONTROL SYSTEM

side.
(1)Turn ignition switch ON.
(2)Measure voltage between terminals 2(3), 1(1) of door
lock control switch connector and body ground, when
door lock control switch is pressed to the lock side, un-
lock side and OFF position.
Remove the door trim.
Check voltage between terminals 2(3), 1(1) of door lock control switch
connector and body ground.
Switch position
Lock side
Unlock side
Terminal
The terminal number without brackets is for the LH,
the number with brackets is for the RH.
OFF
Proceed to next circuit inspection shown on matrix
chart (See page BE±123).
Disconnect the door lock control switch connector.
Check door lock control switch.
Switch position
Lock side
Unlock side
Terminal
The terminal number without brackets is for the LH,
the number with brackets is for the RH.
OFF
Replace door lock control switch.
Check continuity between terminals 2(3), 1(2), 8(4) of
door lock control switch connector, when door lock con-
trol switch is pressed to the lock side, and unlock side
and OFF position.
Check harness and connectors between ECU and door lock control
switch, switch and body ground (See page IN±30).
Check and replace ECU *1
Repair or replace harness or connector.
Lock and/or unlock using the Door Lock
Control Switch cannot be done, neither on
the driver's side nor on the passenger's
side.
*1:Malfunction of the ECU can be considered
possible only when the problem symptom
follows:
INSPECTION PROCEDURE
± BODY ELECTRICAL SYSTEMBE±157THEFT DETERRENT AND DOOR LOCK CONTROL SYSTEM

Key Unlock Warning Switch Circuit
CIRCUIT DESCRIPTION
The key unlock warning switch goes on when the ignition key is inserted in the key cylinder and goes off when
the ignition key is removed.
The ECU operates the key confinement prevention function while the key unlock warning switch is on.
BE±160± BODY ELECTRICAL SYSTEM
THEFT DETERRENT AND DOOR LOCK CONTROL SYSTEM