Lexus RX300 (MCU15). Service manual - part 145

I05472

Wire Harness Side

I19116

Reclining

Front

Back

Forward

Rear

Lifter

Up

Down

Down

Front 
Vertical 
UP

–

BODY ELECTRICAL

POWER SEAT CONTROL SYSTEM

BE–127

LEXUS RX300   (RM785E)

2.

INSPECT DRIVER’S POWER SEAT SWITCH CIRCUIT

(a)

Disconnect the switch connector and connect the seat
wire harness to the floor wire harness.

(b)

Inspect the connector on the wire harness side.

Tester connection

Condition

Specified condition

4 – Ground

Constant

Continuity

1 – Ground

Constant

Battery positive voltage

If circuit is not as specified, inspect the circuits connected to oth-
er parts.

3.

INSPECT PASSENGER’S (LHD)/DRIVER’S (RHD)
POWER SEAT SWITCH CONTINUITY

Slide switch:

Switch position

Tester connection

Specified condition

FRONT

1 – 9

4 – 6

Continuity

OFF

4 – 6

4 – 9

Continuity

BACK

1 – 6

4 – 9

Continuity

Front vertical switch:

Switch position

Tester connection

Specified condition

UP

1 – 5

4 – 10

Continuity

OFF

4 – 5

4 – 10

Continuity

DOWN

1 – 10

4 – 5

Continuity

Lifter switch:

Switch position

Tester connection

Specified condition

UP

1 – 8

4 – 7

Continuity

OFF

4 – 7

4 – 8

Continuity

DOWN

1 – 7

4 – 8

Continuity

I05472

Wire Harness Side

I04161

RELEASE

FORWARD

I04162

Wire Harness Side

BE–128

–

BODY ELECTRICAL

POWER SEAT CONTROL SYSTEM

LEXUS RX300   (RM785E)

Reclining switch:

Switch position

Tester connection

Specified condition

FORWARD

1 – 3

2 – 4

Continuity

OFF

2 – 4

3 – 4

Continuity

REAR

1 – 2

3 – 4

Continuity

If continuity is not as specified, replace the switch.

4.

INSPECT PASSENGER’S POWER SEAT SWITCH CIR-
CUIT

(a)

Disconnect the switch connector and connect the seat
wire harness to the floor wire harness.

(b)

Inspect the connector on the wire harness side.

Tester connection

Condition

Specified condition

4 – Ground

Constant

Continuity

1 – Ground

Constant

Battery positive voltage

If circuit is not as specified, inspect the circuits connected to oth-
er parts.

5.

INSPECT LUMBAR SUPPORT SWITCH CONTINUITY

Switch position

Tester connection

Specified condition

FORWARD

1 – 4

2 – 3

Continuity

OFF

1 – 3

2 – 3

Continuity

RELEASE

1 – 3

2 – 4

Continuity

If continuity is not as specified, replace the switch.

6.

INSPECT LUMBAR SUPPORT SWITCH CIRCUIT

(a)

Disconnect the switch connector and connect the seat
wire harness to the floor wire harness.

(b)

Inspect the connector on the wire harness side.

N21865

(a)

(b)

2

1

1

2

N21866

2

1

N21867

2

1

N21865

(a)

(b)

2

1

1

2

–

BODY ELECTRICAL

POWER SEAT CONTROL SYSTEM

BE–129

LEXUS RX300   (RM785E)

Tester connection

Condition

Specified condition

3 – Ground

Constant

Continuity

4 – Ground

Constant

Battery positive voltage

If circuit is not as specified, inspect the circuits connected to oth-
er parts.

7.

INSPECT SLIDE MOTOR OPERATION

(a)

Connect the positive (+) lead from the battery to terminal
1 and the negative (–) lead to terminal 2, check that the
motor turns counterclockwise.

(b)

Reverse the polarity, check that the motor turns clock-
wise.

If operation is not as specified, replace the seat adjuster.

8.

INSPECT SLIDE MOTOR PTC THERMISTOR OPERA-
TION
( ): Passenger side

(a)

Connect the positive (+) lead from the battery to terminal
1 (2), the positive (+) lead from the ammeter to terminal
2 (1) and the negative (–) lead to the battery negative (–)
terminal, then move the seat cushion to the front position.

(b)

Continue to apply voltage, check that current changes to
less than 1 ampere within 4 to 90 seconds.

(c)

Disconnect the leads from terminals.

(d)

Approximately 60 seconds later, connect the positive (+)
lead from the battery to terminal 2 (1) and the negative (–)
lead to terminal 1 (2), check that the seat cushion begins
to move backwards.

If operation is not as specified, replace the seat adjuster.

9.

INSPECT FRONT VERTICAL MOTOR OPERATION

(a)

Connect the positive (+) lead from the battery to terminal
1 and the negative (–) lead to terminal 2, check that the
motor turns counterclockwise.

(b)

Reverse the polarity, check that the motor turns clock-
wise.

If operation is not as specified, replace the seat adjuster.

N22086

2

1

N22087

2

1

N21865

(a)

1

(b)

2

2

1

N22088

2

1

N22089

2

1

BE–130

–

BODY ELECTRICAL

POWER SEAT CONTROL SYSTEM

LEXUS RX300   (RM785E)

10.

INSPECT FRONT VERTICAL MOTOR PTC THERM-
ISTOR OPERATION

(a)

Connect the positive (+) lead from the battery to terminal
1, the positive (+) lead from the ammeter to terminal 2 and
the negative (–) lead to the battery negative (–) terminal,
then move the seat cushion to the highest position.

(b)

Continue to apply voltage, check that the current changes
to less than 1 ampere within 4 to 90 seconds.

(c)

Disconnect the leads from the terminals.

(d)

Approximately 60 seconds later, connect the positive (+)
lead from the battery to terminal 2 and the negative (–)
lead to terminal 1, check that the seat cushion begins to
descend.

If operation is not as specified, replace the seat adjuster.

11.

INSPECT LIFTER MOTOR OPERATION

(a)

Connect the positive (+) lead from the battery to terminal
1 and the negative (–) lead to terminal 2, check that the
motor turns counterclockwise.

(b)

Reverse the polarity, check that the motor turns clock-
wise.

If operation is not as specified, replace the seat adjuster.

12.

INSPECT LIFTER MOTOR PTC THERMISTOR OPERA-
TION

(a)

Connect the positive (+) lead from the battery to terminal
2, the positive (+) lead from the ammeter to terminal 1 and
the negative (–) lead to the battery negative (–) terminal,
then move the seat cushion to the highest position.

(b)

Continue to apply voltage, check that the current changes
to less than 1 ampere within 4 to 90 seconds.

(c)

Disconnect the leads from the terminals.

(d)

Approximately 60 seconds later, connect the positive (+)
lead from the battery to terminal 1 and the negative (–)
lead to terminal 2, check that the seat cushion begins to
descend.

If operation is not as specified, replace the seat adjuster.