Lexus SC300 / Lexus SC400. Service manual — part 1013

188

SHIFT LOCK

1E

2

1E

17

1I

10

7

8

SHIFT LOCK
CONTROL SW

SHIFT LOCK
SOLENOID

TIMER

3

2

4

5

1

P1

–P

P2

SLS–

SLS+

1

2

IF

15A
CIG

15A
ECU–IG

15A
STOP

KEY INTERLOCK
SOLENOID
[IGNITION SW]

STOP LIGHT
SW

ACC

IG

STP

KLS+

E

L–R

L

G–W

G

G–R

V

W–

B

W–

B

W–

B

L–R

B–

R

G–

W

G–

W

W

B–

R

L–R

SHIFT LOCK ECU

FROM POWER SOURCE SYSTEM (SEE PAGE 56)

I15

S12

S10

1H

1

3A

5

3G

6

1E

20

IG1

12

1H

13

1J

1

1E

18

V

3A

1

3H

15

W–B

189

WHEN THE IGNITION SW IS TURNED TO ACC POSITION THE CURRENT FROM THE CIG FUSE FLOWS TO TERMINAL 1 OF THE SHIFT
LOCK ECU, IN THE ON POSITION, THE CURRENT FROM THE ECU–IG FUSE FLOWS TO TERMINAL 5 OF THE ECU.

1. SHIFT LOCK MECHANISM

WITH THE IGNITION SW ON, WHEN A SIGNAL THAT THE BRAKE PEDAL IS DEPRESSED (STOP LIGHT SW ON) AND A SIGNAL THAT
THE SHIFT LEVER IS PUT IN “P” RANGE (CONTINUITY BETWEEN P1 AND P OF THE SHIFT LOCK CONTROL SW) IS INPUT TO THE
ECU, THE ECU OPERATES AND CURRENT FLOWS FROM TERMINAL 5 OF THE ECU

→

TERMINAL SL+ OF THE SHIFT LOCK

SOLENOID

→

SOLENOID

→

TERMINAL SL–

→

TERMINAL 3 OF THE ECU

→

GROUND. THIS CAUSES THE SHIFT LOCK SOLENOID TO

TURN ON (PLATE STOPPER DISENGAGES) AND THE SHIFT LEVER CAN SHIFT INTO RANGE OTHER THAN THE “P” RANGE.

2. KEY INTER LOCK MECHANISM

WITH THE IGNITION SW ON OR ACC POSITION, WHEN THE SHIFT LEVER IS PUT IN “P” RANGE (NO CONTINUITY BETWEEN P2 AND P
OF SHIFT LOCK CONTROL SW), THE CURRENT FLOWING FROM TERMINAL 2 OF THE ECU

→

KEY INTER LOCK SOLENOID IS CUT

OFF. THIS CAUSES THE KEY INTER LOCK SOLENOID TO TURN OFF (LOCK LEVER DISENGAGES FROM LOCK POSITION) AND THE
IGNITION KEY CAN BE TURNED FROM ACC TO LOCK POSITION. IF THE IGNITION IS LEFT IN ACC OR ON POSITION WITH THE SHIFT
LEVER IN OTHER THAN “P” RANGE, THAN AFTER APPROX. ONE HOUR THE ECU OPERATES TO RELEASE THE LOCK.

S10

SHIFT LOCK ECU

1–GROUND : APPROX. 12 VOLTS WITH IGNITION SW AT ACC OR ON POSITION
5–GROUND : APPROX. 12 VOLTS WITH IGNITION SW AT ON POSITION
3–GROUND : ALWAYS CONTINUITY
4–GROUND : APPROX. 12 VOLTS WITH BRAKE PEDAL DEPRESSED

S12

STOP LIGHT SW

2–1 : CLOSED WITH BRAKE PEDAL DEPRESSED

: PARTS LOCATION

CODE

SEE PAGE

CODE

SEE PAGE

CODE

SEE PAGE

I15

29

S10

29

S12

29

: JUNCTION BLOCK AND WIRE HARNESS CONNECTOR

CODE

SEE PAGE

JUNCTION BLOCK AND WIRE HARNESS (CONNECTOR LOCATION)

1E

20

INSTRUMENT PANEL WIRE

1H

1I

20

COWL WIRE

1J

20

COWL WIRE

3A

3G

22

INSTRUMENT PANEL WIRE

3H

: CONNECTOR JOINING WIRE HARNESS AND WIRE HARNESS

CODE

SEE PAGE

JOINING WIRE HARNESS AND WIRE HARNESS (CONNECTOR LOCATION)

IG1

36

INSTRUMENT PANEL WIRE AND COWL WIRE (R/B NO. 5)

: GROUND POINTS

CODE

SEE PAGE

GROUND POINTS LOCATION

IF

36

LEFT KICK PANEL

X

7

8

1

2

3

4

5

1

2

I1 5

S 1 0

S 1 2

B L A C K

SYSTEM OUTLINE

SERVICE HINTS

177

SRS AIRBAG

NOTICE: When inspecting or repairing the SRS AIRBAG, perform the operation in accordance with the
following precautionary instructions and the procedure and precautions in the Repair Manual for the applicable
model year.

Malfunction symptoms of the airbag system are difficult to confirm, so the diagnostic codes become the most
important source of information when troubleshooting.
When troubleshooting the airbag system, always inspect the diagnostic codes before disconnecting the
battery.

Work must be started after 30 seconds or longer from the time the Ignition SW is set to the “LOCK” position
and the negative (–) terminal cable is disconnected from the battery.
(The airbag system is equipped with a back–up power source so that if work is started within 30 seconds of
disconnecting the negative (–) terminal cable of the battery, the airbag may be deployed.)
When the negative (–) terminal cable is disconnected from the battery, memory of the clock and audio systems
will be cancelled. So before starting work, make a record of the contents memorized by each memory system.
Then when work is finished, reset the clock and audio system as before.
When the vehicle has tilt and telescopic steering, power seat, outside rear view mirror and power shoulder
belt anchorage, which are all equipped with memory function, it is not possible to make a record of the memory
contents. So when the operation is finished, it will be necessary to explain this fact to the customer, and
request the customer to adjust the features and reset the memory.
To avoid erasing the memory of each memory system, never use a back–up power supply from outside the
vehicle.

When removing the steering wheel pad or handling a new steering wheel pad, keep the pad upper surface
facing upward. Also, lock the lock lever of the twin lock type connector at the rear of the pad and take care
not to damage the connector.
(Storing the pad with its metallic surface up may lead to a serious accident if the airbag inflates for some
reason).

Store the steering wheel pad where the ambient temperature remains below 93

°

C (200

°

F), without high

humidity and away from electrical noise.

Never use airbag parts from another vehicle. When replacing airbag parts, replace them with new parts.

Never disassemble or repair the steering wheel pad, center airbag sensor assembly or front airbag sensors.

Before repairing the body, remove the airbag sensors if during repair shocks are likely to be applied to the
sensors due to vibration of the body or direct tapping with tools or other parts.

Do not reuse a steering wheel pad or front airbag sensors.
After evaluating whether the center airbag sensor assembly is damaged or not, decide whether or not to reuse
it. (See the Repair Manual for the method for evaluating the center airbag sensor assembly.)

When troubleshooting the airbag system, use a high–impedance (Min. 10k

Ω/

V) tester.

The vehicle wiring harness exclusively for the airbag system is distinguished by corrugated yellow tubing, as
are the connectors.

Do not measure the resistance of the airbag squib.
(It is possible this will deploy the airbag and is very dangerous.)

If the wire harness used in the airbag system is damaged, replace the whole wire harness assembly.
When the connector to the airbag front sensors can be repaired alone (when there is no damage to the wire
harness), use the repair wire specially designed for the purpose.
(Refer to the Repair Manual for the applicable Model year for details of the replacement method.)

INFORMATION LABELS (NOTICES) are attached to the periphery of the airbag components. Follow the
instructions on the notices.

178

SRS AIRBAG

The airbag system has connectors which possess the functions described below:

1. AIRBAG ACTIVATION PREVENTION MECHANISM

Each connector contains a short spring plate. When the
connector is disconnected, the short spring plate
automatically connects the power source and grounding
terminals of the squib to preclude a potential difference
between the terminals.

2. ELECTRICAL CONNECTION CHECK MECHANISM

This mechanism is designed to electrically check if
connectors are connected correctly and completely.
The electrical connection check mechanism is designed so
that the connection detection pin connects with the
diagnosis terminals when the connector housing lock is in
the locked condition.