TOYOTA SUPRA 1995 Service Repair Manual

INSPECTION PROCEDURE
(See page BE±123).
Check harness and connector between theft deterrent and door lock ECU
and indicator light, indicator light and body ground (See page IN±30).
(2) Remove instrument panel cluster finish panel.
(3) Disconnect telltale light RH connector.
Connect positive (+) lead to terminal 10 and neg-
ative (±) lead to terminal 9 of indicator light con-
nector.
Indicator light comes on.
Replace telltale light RH.
Repair or replace harness or connector.
Check and replace theft deterrent and door
lock ECU. *1*1: When there is a malfunction that the theft de-
terrent system cannot be set, proceed to the
next numbered circuit inspection shown on
matrix chart (See page BE±123).
Check indicator light
± BODY ELECTRICAL SYSTEMBE±129THEFT DETERRENT AND DOOR LOCK CONTROL SYSTEM

Starter Relay Circuit
CIRCUIT DESCRIPTION
When the theft deterrent system is activated, contact (a) in the ECU becomes open, creating an open circuit
in terminal ST circuit and making the starter inoperative (starter cut).
In this condition, if one of the following operations is done, the contact (a) in the ECU is grounded, thus can-
celling the starter cut:
(1) The front LH and RH door is unlocked with a key. BE±130
± BODY ELECTRICAL SYSTEM
THEFT DETERRENT AND DOOR LOCK CONTROL SYSTEM

INSPECTION PROCEDURE
HINT: This troubleshooting is based on the premise that engine cranking occurs.
If the engine does not crank, proceed to engine troubleshooting on page EG±381 or 487 (Vol. 1).
(See page IN±30).
(1)Remove instrument panel panel.
(See BO section.)
(2)Disconnect the ECU connector.
Measure voltage between terminal SRLY of theft
deterrent ECU connector and body ground when
ignition switch is turned on.
Voltage: 10 ± 14 V
Check and replace theft deterrent ECU.
Check voltage between terminal SRLY of theft deterrent and door lock
ECU connector and body ground.
Check and repair harness and connector between starter and theft deterrent and door lock ECU
± BODY ELECTRICAL SYSTEMTHEFT DETERRENT AND DOOR LOCK CONTROL SYSTEMBE±131

Horn Relay Circuit
CIRCUIT DESCRIPTION
When the theft deterrent system is activated, it causes the Tr in the ECU to switch on and off in approximately
0.2 sec. cycles. This switches the horn relay on and off, thus the horns blow (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 horn relay switches
off, thus stopping the horns 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±132± BODY ELECTRICAL SYSTEMTHEFT DETERRENT AND DOOR LOCK CONTROL SYSTEM

INSPECTION PROCEDURE
(See page IN±30).
Check and repair harness and connector between theft deterrent and door lock ECU and horn
relay (See page IN±30).
(1) Remove instrument panel.
(See BO section)
(2) Disconnect the ECU connector.
Voltage: 10 ± 14 V
Replace telltale light RH.
Check and replace theft deterrent and door lock
ECU.
Check voltage between terminal HORN of theft deterrent and door lock
ECU connector and body ground.
Measure voltage between terminal HORN of theft
deterrent ECU connector and body ground.
± BODY ELECTRICAL SYSTEMBE±133THEFT DETERRENT AND DOOR LOCK CONTROL SYSTEM

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

(See page IN±30).
Check voltage between terminal SH of theft deterrent horn connector
and body ground.
Remove the theft deterrent horn and disconnect the
connector.
Measure voltage between terminal 1 of theft deter-
rent horn connector and body ground.
Voltage: 10 ± 14 V
Check and repair harness and connector between
HORN fuse and theft deterrent horn.
Connect positive (+) lead to terminal 1 and negative
(±) lead to terminal 2 of theft deterrent horn connec-
tor.
Theft deterrent horn blows.
Replace theft deterrent horn.
Check theft deterrent horn.
Check harness and connector between theft deterrent and door lock ECU
and theft deterrent horn (See page IN±30).
Check and repair harness or connector.
Check and replace theft deterrent ECU.
INSPECTION PROCEDURE
± BODY ELECTRICAL SYSTEMBE±135THEFT 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

INSPECTION PROCEDURE
HINT: The flow chart below is based on the premise that the headlights light up normally whenever the light con±
trol switch is operated. If headlight operation is not normal when the light control switch is operated, pro±
ceed to troubleshooting on page BE±11.
Check and replace theft deterrent and door lock
ECU.
Measure voltage between terminal HEAD 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 headlight
control relay (See page IN±30).
Check voltage between terminal HEAD of theft deterrent and door lock
ECU connector and body ground.
(1) Remove instrument panel.
(See BO section)
(2) Disconnect the ECU connector.
± BODY ELECTRICAL SYSTEMBE±137THEFT 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