Lexus RX300 (MCU15). Service manual - part 312

DI6QT–04

I19137

Cruise Control Actuator
D

 Actuator Motor

D

 Actuator Magnetic Clutch

Park/Neutral Position
Switch

CRUISE MAIN Indicator
Light

Cruise Control ECU

Stop Light Switch

Instrument Panel J/B
D

 GAUGE Fuse

D

 ECU–IG Fuse

D

 HEATER Fuse

Cruise Control Switch
D

 Main Switch

D

 Control Switch

LHD:

RHD:

CRUISE MAIN Indicator
Light

Instrument Panel J/B
D

 GAUGE Fuse

D

 ECU–IG Fuse

D

 HEATER Fuse

Stop Light Switch

Cruise Control ECU

Cruise Control Switch
D

 Main Switch

D

 Control Switch

DI–480

–

DIAGNOSTICS

CRUISE CONTROL SYSTEM

LEXUS RX300   (RM785E)

PARTS LOCATION

DI1KT–15

I00293

C16

–

DIAGNOSTICS

CRUISE CONTROL SYSTEM

DI–481

LEXUS RX300   (RM785E)

TERMINALS OF ECU

Symbols (Terminals No.)

Wiring Color

Condition

STD Voltage (V)

STP ↔ GND 

G W ↔ BR

Depress brake pedal

10 – 16 V

STP ↔ GND 

(C16–3 ↔ C16–16)

G–W ↔ BR

Release brake pedal

Below 1 V

D ↔ GND (C16 4 ↔ C16 16)

G B ↔ BR

Shift to positions except D

Below 1 V

D ↔ GND (C16–4 ↔ C16–16)

G–B ↔ BR

Shift to D position

10 – 16 V

PI ↔ GND (C16 5 ↔ C16 16)

W G ↔ BR

Ignition switch ON

Cruise control main switch ON

Below 1.2 V

PI ↔ GND (C16–5 ↔ C16–16)

W–G ↔ BR

Ignition switch ON

Cruise control main switch OFF

10 – 16 V

TC ↔ GND

Ignition switch ON

10 – 16 V

TC ↔ GND

 (C16–10 ↔ C16–16)

P–B ↔ BR

Ignition switch ON

Connect terminals Tc and E1 of diagnostic check connector

Below 1 V

ECT ↔ GND 

R Y ↔ BR

During driving 

Gear position 3rd

10 – 16 V

ECT ↔ GND 

(C16–6 ↔ C16–16)

R–Y ↔ BR

During driving 

Gear position O/D

Below 1 V

MC ↔ GND 

L R ↔ BR

During cruise control driving

COAST switch held ON

9 – 15 V

MC ↔ GND 

(C16–7 ↔ C16–16)

L–R ↔ BR

During cruise control driving

ACC switch held ON

Below 1 V

L ↔ GND 

L Y ↔ BR

During cruise control driving

9 – 15 V

L ↔ GND 

(C16–8 ↔ C16–16)

L–Y ↔ BR

Except during cruise control driving

Below 1 V

B ↔ GND 

(C16–2 ↔ C16–16)

B–R ↔ BR

Ignition switch ON

10 – 16 V

Ignition switch ON

10 – 16 V

Ignition switch ON

CANCEL switch held ON

6.0 – 11.0 V

CCS ↔ GND 

(C16–11 ↔ C16–16)

L ↔ BR

Ignition switch ON

SET/COAST switch held ON

4.0 – 7.9 V

(

)

Ignition switch ON

RES/ACC switch held ON

2.0 – 4.6 V

Ignition switch ON

MAIN switch held ON

Below 0.5 V

DI–482

–

DIAGNOSTICS

CRUISE CONTROL SYSTEM

LEXUS RX300   (RM785E)

SPD ↔ GND 

(C16 12 ↔ C16 16)

V–W ↔ BR

Engine start

Car stoppage.

Below 1.5 V or

4.7 – 16 V

(C16–12 ↔ C16–16)

V W ↔ BR

During driving (Pulse generated).

3 – 7 V

IDL ↔ GND 

B Y ↔ BR

Ignition switch ON

Throttle valve fully opened.

10 – 16 V

IDL ↔ GND 

(C16–13 ↔ C16–16)

B–Y ↔ BR

Ignition switch ON

Throttle valve fully closed.

Below 1.5 V

OD ↔ GND

Y G ↔ BR

During cruise control driving

OD switch ON.

10 – 16 V

OD ↔ GND

(C16–14 ↔ C16–16)

Y–G ↔ BR

During cruise control driving

OD switch OFF (3rd driving)

Below 1 V

MO ↔ GND 

L B ↔ BR

During cruise control driving

ACC switch hold ON

9 – 15 V

MO ↔ GND 

(C16–15 ↔ C16–16)

L–B ↔ BR

During cruise control driving

COAST switch hold ON

Below 1 V

GND ↔ Body  Ground

(C16–16 ↔ Body  Ground)

BR ↔ Body

Ground

Constant

Below 1 V

DI08L–22

–

DIAGNOSTICS

CRUISE CONTROL SYSTEM

DI–483

LEXUS RX300   (RM785E)

PROBLEM SYMPTOMS TABLE

Symptom

Suspect Area

See page

SET not occurring or CANCEL occurring.

(DTC is Normal)

13.Main Switch Circuit (Cruise control switch)

14.Vehicle Speed Sensor

15.Control Switch Circuit (Cruise control switch)

16.Stop Light Switch Circuit

17.Neutral Start Switch Circuit

18.Actuator Motor Circuit

19.Cruise Control Cable

20.Cruise Control ECU

DI–502

DI–492

DI–502

DI–505

DI–507

DI–484

DI–516

IN–32

SET not occurring or CANCEL occurring.

(DTC dose not output)

1. ECU Power Source Circuit

2. Cruise Control ECU

DI–499

IN–32

Actual vehicle speed deviates above or below the set speed.

1. Cruise Control Cable

2. Vehicle Speed Signal Abnormal

3. Electronically  Controlled Transmission

Communication Circuit

4. Actuator Motor Circuit

5. Idle Signal Circuit (Main throttle position sensor)

6. Cruise Control ECU

DI–516

DI–492

DI–517

DI–484

DI–496

IN–32

Gear shifting frequent between 3rd O/D when driving on uphill

road. (Hurting)

1. Electronically  Controlled Transmission

 Communication Circuit

2. Cruise Control ECU

DI–517

IN–32

Cruise control not cancelled, even when brake pedal is de-

pressed.

1. Cruise Control Cable

2. Stop Light Switch Circuit

3. Actuator Motor Circuit

4. Cruise Control ECU

DI–516

DI–505

DI–484

IN–32

Cruise control not cancelled, even when transmission is shifted to

”N” position.

1. Cruise Control Cable

2. Neutral Start Switch Circuit

3. Actuator Motor Circuit

4. Cruise Control ECU

DI–516

DI–507

DI–484

IN–32

Cruise control not cancelled, even when clutch pedal is de-

pressed.

1. Cruise Control Cable

2. Actuator Motor Circuit

3. Cruise Control ECU

DI–516

DI–484

IN–32

Control switch does not operate.

(SET/COAST, ACC/RES, CANCEL not possible)

1. Cruise Control Cable

2. Control Switch Circuit

3. Actuator Motor Circuit

4. Cruise Control ECU

DI–516

DI–510

DI–484

IN–32

SET possible at 40 km/h (25 mph) or less, or CANCEL does not

operate at 40 km/h (25 mph) or less.

1. Cruise Control Cable

2. Vehicle Speed Signal Abnormal

3. Actuator Motor Circuit

4. Cruise Control ECU

DI–516

DI–495

DI–484

IN–32

Poor response is in ACCEL and RESUME modes.

1. Cruise Control Cable

2. Electronically  Controlled Transmission

Communication Circuit

3. Actuator Motor Circuit

4. Cruise Control ECU

DI–516

DI–517

DI–484

IN–32

O/D does not resume, even though the road is not uphill.

1. Electronically  Controlled Transmission

 Communication Circuit

2. Cruise Control ECU

DI–517

IN–32

DTC memory is erased.

Cruise Control ECU

IN–32

DTC is not output, or is output when should not be.

1. Diagnosis Circuit

2. Cruise Control ECU

DI–514

IN–32

Cruise MAIN indicator light remains ON or falls to light up.

Cruise MAIN Indicator Light Switch Circuit

DI–514