Lexus RX300 (MCU15). Service manual - part 320

I19255

Cruise Control ECU

PI

W–G

To
DLC3

17

1

R–W

3E

3A

J/B No.3

R–W

Instrument Panel J/B

7

1C

1K

13

B–Y

4

Ignition Switch

2

W–L

Instrument Panel J/B

AM1

HEATER

6

1

1A

W

3

Battery

CRUISE MAIN
Indicator Light
(in Combination Meter ECU)

C10

C12

5

C16

2

1

IE2

10

5

1

1C

ALT

5

W

AM1

IG1

FL BLOCK

W–G

W–G

DI–512

–

DIAGNOSTICS

CRUISE CONTROL SYSTEM

LEXUS RX300   (RM785E)

CRUISE MAIN Indicator Light Circuit

CIRCUIT DESCRIPTION

When the cruise control main switch is turned ON, CRUISE MAIN indicator light lights up.

WIRING DIAGRAM

DI090–36

I16979

ON

PI

(–)

(+)

–

DIAGNOSTICS

CRUISE CONTROL SYSTEM

DI–513

LEXUS RX300   (RM785E)

INSPECTION PROCEDURE

1

Check voltage between terminals PI and GND of cruise control ECU connector.

PREPARATION:
Tun ignition switch ON.
CHECK:
Measure voltage between terminals PI and GND of cruise con-
trol ECU connector when main switch is ON and OFF.
OK:

Switch position

Voltage

OFF

10 – 16 V

ON

Below 1.2 V

OK

Proceed to next circuit inspection shown in
problem symptom table (See page DI–483).

NG

2

Check combination meter (See page BE–68).

NG

Replace combination meter.

OK

Check and replace cruise control ECU (See
page IN–32).

I19256

Cruise Control ECU

5

10

TC

To
CRUISE MAIN
Indicator Light

J/B No. 5

3

IF

PI

C16

W–B

CG

P–B

C/C

1

C16

5B

13

4

TC

W–B

11

5B

W–G

W–G

DLC3

DI–514

–

DIAGNOSTICS

CRUISE CONTROL SYSTEM

LEXUS RX300   (RM785E)

Diagnosis Circuit

CIRCUIT DESCRIPTION

This circuit sends a signal to the ECU that outputs DTC.

WIRING DIAGRAM

DI091–24

N09214

AB0119

I14387

ON

Tc

CG

–

DIAGNOSTICS

CRUISE CONTROL SYSTEM

DI–515

LEXUS RX300   (RM785E)

INSPECTION PROCEDURE

1

Check voltage between terminals Tc and CG

 

of DLC3.

PREPARATION:
Turn ignition switch ON.
CHECK:
Measure voltage between terminals Tc and CG of DLC3.
OK:

Voltage: 10 – 14 V

OK

Proceed to next circuit inspection shown in
problem symptom table (See page DI–483).

NG

2

Check harness and connector between cruise control ECU and DLC3, DLC3 and
body ground (See page IN–32).

NG

Repair or replace harness or connector.

OK

Check and replace cruise control ECU (See
page IN–32).