Lexus RX300 (MCU15). Manual — part 241

DI–196

–

DIAGNOSTICS

AUTOMATIC TRANSAXLE

LEXUS RX300 (RM785E)

3

Check harness and connector between cruise control ECU and Engine & ECT
ECU (See page IN–32).

NG

Repair or replace the harness or connector.

OK

Check and replace the Engine & ECT ECU
(See page IN–32).

D10061

1

3A

5

3E

R–W

1

C12
Combination Meter

R–W

11
IJ1

R–W

9

E9 ODLP

Engine & ECT ECU

R–W

13
1K

Heater

7

1C

B–Y

4 IG1

Ignition Switch

AM1 2

W–L

6

1C

AM1 2

1

1

1A

W

5

F11 Fusible Link
Block

ALT

3

W

Battery

W–B

O2
O/D Main Switch

6

3 GR–L

IJ1

16

GR–L

IH1

7

GR–L

12

E6 ODMS

IH

W–B

9

3H

8

3H

6

15
IJ1

(RHD)(LHD)

J/B No. 3

Instrument Panel J/B

Instrument Panel J/B

J/B No. 3

O/D OFF

–

DIAGNOSTICS

AUTOMATIC TRANSAXLE

DI–197

LEXUS RX300 (RM785E)

O/D Main Switch & O/D OFF Indictor Light Circuit

CIRCUIT DESCRIPTION

The O/D main switch is a momentary type switch. When pressing the O/D main switch, the O/D OFF indicator
light lights up and Engine & ECT ECU prohibits shifting to O/D, and when pressing it again, the O/D OFF
indicator light goes off and Engine & ECT ECU allows shifting to O/D. Turning the IG switch OFF will reset
the O/D OFF indicator light.

WIRING DIAGRAM

DI1AW–09

D07491

1

3

DI–198

–

DIAGNOSTICS

AUTOMATIC TRANSAXLE

LEXUS RX300 (RM785E)

INSPECTION PROCEDURE

1

Check operation of O/D main switch.

PREPARATION:
Turn the ignition switch ON.
CHECK:
(a)

Check O/D OFF indicator light when O/D main switch is
pushed in to ON.

(b)

Check O/D OFF indicator light when O/D main switch is
pushed again.

OK:

(a) O/D OFF indicator light lights up.
(b) O/D OFF indicator light goes off.

OK

Proceed to next inspection shown on symp-
toms problem tables (See page DI–160).

NG

2

Check and replace the combination meter (See page BE–68).

NG

Replace the

combination meter.

OK

3

Check O/D main switch.

PREPARATION:
Disconnect the O/D main switch connector.
CHECK:
Check continuity between terminals 1 and 3 of O/D main switch
connector.
OK:

O/D main switch condition

Specified condition

Press continuously O/D main switch

Continuity

Release O/D main switch

No continuity

NG

Replace and repair O/D main switch.

OK

D07186

ON

(–)

(+)

ODMS

D07185

ON

ODLP

(–)

(+)

–

DIAGNOSTICS

AUTOMATIC TRANSAXLE

DI–199

LEXUS RX300 (RM785E)

4

Check voltage between terminal ODMS of Engine & ECT ECU and body ground.

PREPARATION:
Turn the ignition switch ON.
CHECK:
Check voltage between terminal ODMS of Engine & ECT ECU
and body ground when O/D main switch is ON and OFF.
OK:

O/D main switch condition

Specified voltage

Press continuously O/D main switch

Below 1.0 V

Release O/D main switch

10 – 14 V

OK

Check and replace the Engine & ECT ECU (See
page IN–22).

NG

5

Check voltage between terminal ODLP of Engine & ECT ECU and body ground.

PREPARATION:
(a)

Disconnect the connector of Engine & ECT ECU.

(b)

Turn the ignition switch ON.

CHECK:
Check voltage between terminal ODLP of Engine & ECT ECU
and body ground.
OK:

Voltage: 7.5 – 14 V

OK

Check and replace the Engine & ECT ECU (See
page IN–22).

NG

Check and replace harness and connector between combination meter and Engine & ECT ECU,
O/D main switch and Engine & ECT ECU, O/D main switch and body ground (See page IN–22).