Lexus SC300 / Lexus SC400. Service manual — part 972

148

CRUISE CONTROL

1E

12

1K

13

2

1

3F

4

1B

5

3E

1

B

BATT

A

1

A

14

SPD

GND

CMS

CCS

PI

TC

A

10

B

20

11

4

10

IG1

7

IK1

10

10A
DOME

15A
ECU–IG

10A
GAUGE

1H

10

CRUISE CONTROL
INDICATOR LIGHT
[COMB. METER]

TDCL

CHECK
CONNECTOR

CRUISE CONTROL ECU

CRUISE CONTROL SW
[COMB. SW]

E

CMS

CCS

MAIN

CANCEL

RESUME/
ACCEL

SET/
COAST

CRUISE CONTROL

A/D

TC

TC

Y–

B

Y–B

L

15

5

R

R

B–

R

Y

Y

PP

W–

B

BR

W–

B

Y–

B

P–

B

P–

B

P–

B

R–

L

L

Y–

B

P–

B

Y–

B

C19

C15

T 6

C 3

FROM POWER SOURCE SYSTEM (SEE PAGE 56)

IG1

13

IG1

15

3A

8

3H

12

3E

3

IH

IG

20

13

4

18

5

8

6

14

15

3A

4

3D

13

W–B

W–

B

P–

B

C12

, C1 4

A

B

3C

4

2

149

1K

4

1I

10

B

9

B

64

A

12

1

IJ2

2

IJ2

1

IJ1

6

PARKING
BRAKE SW

M

4

2

4

3

1

5

7

6

2

3

1

25A
STOP

7. 5A
ST

POTENTIO METER

CRUISE CONTROL ACTUATOR

GND

L

MC

MO

VR3

VR2

VR1

MA

G

N

E

T

IC

CL

UT

CH

S2

IDL1

OD1

ECT

IDL

OD

VR1

VR2

VR3

MC

MO

L

STP–

N&C

STP+

CRUISE CONTROL ECU

STOP
LIGHT
SW

B–W

B–W

W

B–

W

W

W

G–

W

BR

–

Y

R

W–

R

W–

R

R

BR

–

Y

R–

B

LG

–R

P

LG

G–

R

W

R–

L

R–

B

LG

–R

P

LG

G–

R

B–

W

W–

B

I 9

S12

C19

P 3

C 8

FROM POWER SOURCE SYSTEM (SEE PAGE 56)

R–

W

B

PKB

ENGINE AND ECT ECU

E 9

, E 1 0

I 7

EA

IE2

10

IE2

11

IE2

5

IE2

1

IE2

6

IE2

2

IG1

19

IJ2

9

B

(C

A

NA

DA

)

(US

A

)

R–

L

22

23

9

3

24

25

26

12

11

10

16

1

A

B

IJ2

10

I 9

C24

C23

CLUTCH
START SW

CRUISE
CONTROL
CLUTCH SW

(A/T)

B–

W

B

B–W

B–

W

B–

W

(A/

T

)

(A/T)

1

2

2

2

1

150

CRUISE CONTROL

CURRENT IS APPLIED AT ALL TIMES THROUGH STOP FUSE TO TERMINAL 1 OF THE CONTROL ECU TERMINAL 2 OF STOP LIGHT
SWITCH, AND ALSO THROUGH THE DOME FUSE TO TERMINAL 15 OF CRUISE CONTROL ECU.

WITH THE IGNITION SWITCH TURNED TO ON, THE CURRENT FLOWS THROUGH GAUGE FUSE TO TERMINAL (A)1 OF COMBINATION
METER AND THE CURRENT THROUGH ECU–IG FUSE FLOWS TO TERMINAL 14 OF CRUISE CONTROL ECU.

WHEN THE IGNITION SWITCH IS ON AND THE CRUISE CONTROL MAIN SWITCH IS TURNED ON, A SIGNAL IS INPUT FROM TERMINAL
15 OF CRUISE CONTROL MAIN SWITCH TO TERMINAL 4 OF CRUISE CONTROL ECU. AS A RESULT, THE CRUISE CONTROL ECU
FUNCTIONS AND THE CURRENT TO TERMINAL 14 OF CRUISE CONTROL ECU TO TERMINAL 13 OF CRUISE CONTROL ECU

→

GROUND, AND THE CRUISE CONTROL SYSTEM IS IN A CONDITION READY FOR OPERATION.

AT THE SAME TIME, THE CURRENT THROUGH THE GAUGE FUSE FLOWS FROM TERMINAL (A)1 OF CRUISE CONTROL INDICATOR
LIGHT

→

TERMINAL (B)20

→

TERMINAL 5 OF CRUISE CONTROL ECU

→

TERMINAL 13

→

TO GROUND, CAUSING THE CRUISE

CONTROL INDICATOR LIGHT TO LIGHT UP, INDICATING THAT THE CRUISE CONTROL IS READY FOR OPERATION.

1. SET OPERATION

WHEN THE CRUISE CONTROL MAIN SWITCH IS TURNED ON AND THE SET SWITCH IS PUSHED WITH THE VEHICLE SPEED WITHIN
THE SET LIMIT (APPROX. 40 KM/H, 2.5 MPH TO 200 KM/H, 124 MPH), A SIGNAL IS INPUT TO TERMINAL 18 OF THE CRUISE CONTROL
ECU AND THE VEHICLE SPEED AT THE TIME THE SET SWITCH IS RELEASED IS MEMORIZED IN THE ECU AS THE SET SPEED.

2. SET SPEED CONTROL

DURING CRUISE CONTROL DRIVING, THE ECU COMPARES THE SET SPEED MEMORIZED IN THE ECU WITH THE ACTUAL VEHICLE
SPEED INPUT INTO TERMINAL 20 OF THE CRUISE CONTROL ECU FROM THE SPEED SENSOR, AND CONTROLS THE CRUISE
CONTROL ACTUATOR TO MAINTAIN THE SET SPEED.

WHEN THE ACTUAL SPEED IS LOWER THAN THE SET SPEED, THE ECU CAUSES THE CURRENT TO THE CRUISE CONTROL
ACTUATOR TO FLOW FROM TERMINAL 12

→

TERMINAL 6 OF CRUISE CONTROL ACTUATOR

→

TERMINAL 7

→

TERMINAL 11 OF

CRUISE CONTROL ECU. AS A RESULT, THE MOTOR IN THE CRUISE CONTROL ACTUATOR IS ROTATED TO OPEN THE THROTTLE
VALVE AND THE THROTTLE CABLE IS PULLED TO INCREASE THE VEHICLE SPEED. WHEN THE ACTUAL DRIVING SPEED IS HIGHER
THAN THE SET SPEED, THE CURRENT TO CRUISE CONTROL ACTUATOR FLOWS FROM TERMINAL 11 OF ECU

→

TERMINAL 7 OF

CRUISE CONTROL ACTUATOR

→

TERMINAL 6

→

TERMINAL 12 OF CRUISE CONTROL ECU.

THIS CAUSES THE MOTOR IN THE CRUISE CONTROL ACTUATOR TO ROTATE TO CLOSE THE THROTTLE VALVE AND RETURN THE
THROTTLE CABLE TO DECREASE THE VEHICLE SPEED.

3. COAST CONTROL

DURING THE CRUISE CONTROL DRIVING, WHILE THE COAST SWITCH IS ON, THE CRUISE CONTROL ACTUATOR RETURNS THE
THROTTLE CABLE TO CLOSE THE THROTTLE VALVE AND DECREASE THE DRIVING SPEED. THE VEHICLE SPEED WHEN THE COAST
SWITCH IS TURNED OFF IS MEMORIZED AND THE VEHICLE CONTINUES AT THE NEW SET SPEED.

4. ACCEL CONTROL

DURING CRUISE CONTROL DRIVING, WHILE THE ACCEL SWITCH IS TURNED ON, THE CRUISE CONTROL ACTUATOR PULLS THE
THROTTLE CABLE TO OPEN THE THROTTLE VALVE AND INCREASE THE DRIVING SPEED.

THE VEHICLE SPEED WHEN THE ACCEL SWITCH IS TURNED OFF IS MEMORIZED AND THE VEHICLE CONTINUES AT THE NEW SET
SPEED.

5. RESUME CONTROL

UNLESS THE VEHICLE SPEED FALLS BELOW THE MINIMUM SPEED LIMIT (APPROX. 40 KM/H, 25 MPH) AFTER CANCELING THE SET
SPEED BY THE CANCEL SWITCH, PUSHING THE RESUME SWITCH WILL CAUSE THE VEHICLE TO RESUME THE SPEED SET BEFORE
CANCELLATION.

6. MANUAL CANCEL MECHANISM

IF ANY OF THE FOLLOWING OPERATIONS OCCURS DURING CRUISE CONTROL OPERATION, THE SAFETY MAGNETIC CLUTCH OF
THE ACTUATOR TURNS OFF AND THE MOTOR ROTATES TO CLOSE THE THROTTLE VALVE AND THE CRUISE CONTROL IS
RELEASED.

∗

PLACING THE SHIFT LEVER IN “N” RANGE (NEUTRAL START SWITCH ON)). “SIGNAL INPUT TO TERMINAL 2 OF ECU”

∗

DEPRESSING THE BRAKE LEVER (STOP LIGHT SWITCH ON). “SIGNAL INPUT TO TERMINAL 16 OF ECU”

∗

PULLING THE PARKING BRAKE PEDAL (PARKING BRAKE SWITCH ON). “SIGNAL INPUT TO TERMINAL 3 OF ECU”

∗

PUSHING THE CANCEL SWITCH (CANCEL SWITCH ON). “SIGNAL INPUT TO TERMINAL 18“

SYSTEM OUTLINE

151

7. AUTO CANCEL FUNCTION

A)

IF ANY OF THE FOLLOWING OPERATING CONDITIONS OCCURS DURING CRUISE CONTROL OPERATION, THE SET SPEED IS

ERASED, CURRENT FLOW TO MAGNETIC CLUTCH IS STOPPED AND THE CRUISE CONTROL IS RELEASED. (MAIN SWITCH TURNS
OFF).

WHEN THIS OCCURS, THE IGNITION SWITCH MUST BE TURNED OFF ONCE BEFORE THE MAIN SWITCH WILL TURN ON.

∗

OVER CURRENT TO TRANSISTER DRIVING MOTOR AND/OR MAGNETIC CLUTCH.

∗

WHEN CURRENT CONTINUED TO FLOW TO THE MOTOR INSIDE THE ACTUATOR IN THE THROTTLE VALVE “OPEN” DIRECTION.

∗

OPEN CIRCUIT IN MAGNETIC CLUTCH.

∗

MOMENTARY INTERRUPTION OF VEHICLE SPEED SIGNAL.

∗

SHORT CIRCUIT IN CRUISE CONTROL SWITCH.

∗

MOTOR DOES NOT OPERATE DESPITE THE MOTOR DRIVE SIGNAL BEING OUTPUT.

B)

IF ANY OF THE FOLLOWING CONDITIONS OCCURS DURING CRUISE CONTROL OPERATION, THE SET SPEED IS ERASED AND

THE CRUISE CONTROL IS RELEASED. (THE POWER OF MAGNETIC CLUTCH IS CUT OFF UNTIL THE SET SWITCH IS “ON” AGAIN.)

∗

WHEN THE VEHICLE SPEED FALLS BELOW THE MINIMUM SPEED LIMIT, APPROX. 40 KM/H (2.5 MPH)

∗

WHEN THE VEHICLE SPEED FALLS MORE THAN 16 KM/H (10 MPH) BELOW THE SET SPEED, E.G. ON AN UPWARD SLOPE.

∗

WHEN POWER TO THE CRUISE CONTROL SYSTEM IS MOMENTARILY CUT OFF.

C)

IF ANY OF THE FOLLOWING CONDITIONS OCCURS DURING CRUISE CONTROL OPERATION, THE CRUISE CONTROL IS

RELEASED.

∗

OPEN CIRCUIT FOR TERMINAL 1 OF CRUISE CONTROL ECU AND SPLICE POINT “I 9”.

8. AUTOMATIC TRANSMISSION CONTROL FUNCTION

∗

IN OVERDRIVE. IF THE VEHICLE SPEED BECOMES LOWER THAN THE OVERDRIVE CUT SPEED (SET SPEED MINUS APPROX. 4

KM/H, 2.5 MPH) DURING CRUISE CONTROL OPERATION, SUCH AS DRIVING UP A HILL, THE OVERDRIVE IS RELEASED AND THE
POWER INCREASED TO PREVENT A REDUCTION IN VEHICLE SPEED.

∗

AFTER RELEASING THE OVERDRIVE, VEHICLE SPEED BECOMES HIGHER THAN THE OVERDRIVE RETURN SPEED (SET SPEED

MINUS APPROX. 2 M/H, 1.2 MPH) AND THE ECU JUDGES BY THE SIGNALS FROM POTENTIOMETER OF THE ACTUATOR THAT THE
UPWARD SLOPE HAS FINISHED, OVERDRIVE IS RESUMED AFTER APPROXIMATELY 6 SECONDS.

∗

DURING CRUISE CONTROL DRIVING, THE CRUISE CONTROL OPERATION SIGNAL IS OUTPUT FROM THE CRUISE CONTROL

ECU TO THE ENGINE AND TRANSMISSION ECU. UPON RECEIVING THIS SIGNAL, THE ENGINE AND TRANSMISSION ECU
CHANGES THE SHIFT PATTERN TO NORMAL.

TO MAINTAIN SMOOTH CRUISE CONTROL OPERATION (ON A DOWNWARD SLOPE ETC.), LOCK–UP RELEASE OF THE
TRANSMISSION WHEN THE IDLING POINT OF THE THROTTLE POSITION IS “ON” IS FORBIDDEN.

C 8

CRUISE CONTROL ACTUATOR

1–3 : APPROX. 2K

5–4 : APPROX. 38.5

C15

CRUISE CONTROL SW [COMB. SW]

15–6 :CONTINUITY WITH MAIN SW ON
5–6 :APPROX. 420

WITH CANCEL SW ON

APPROX. 70

WITH RESUME/ACCEL SW ON

APPROX. 200

WITH SET/COAST SW ON

C19

CRUISE CONTROL ECU

14–GROUND : APPROX. 12 VOLTS WITH IGNITION SW AT ON POSITION
1, 15–GROUND :

ALWAYS APPROX. 12 VOLTS

3–GROUND : CONTINUITY WITH PARKING BRAKE LEVER PULLED UP (ONE OF THE CANCEL SW) OR BRAKE LEVER WARNING

SW ON

20–GROUND : 1 PULSE WITH 40CM (DRIVER VEHICLE SLOWLY)
18–GROUND : APPROX. 420

WITH CANCEL SW ON IN CONTROL SW

APPROX. 200

WITH SET/COAST SW ON IN CONTROL SW

APPROX. 70

WITH RESUME/ACCEL SW ON IN CONTROL SW

13–GROUND : ALWAYS CONTINUITY

SERVICE HINTS