Lexus RX300 (MCU15). Manual — part 130

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BODY ELECTRICAL

COMBINATION METER

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LEXUS RX300 (RM785E)

DISASSEMBLY

1.

REMOVE COMBINATION METER COVER

(a)

Remove the 9 screws.

(b)

Remove the combination meter cover.

2.

REMOVE A/C AND COMBINATION METER INTE-
GRATED ECU

(a)

Remove the 4 screws.

(b)

Remove the A/C and combination meter integrated ECU
and 2 combination meter wire.

3.

REMOVE COMBINATION METER CIRCUIT PLATE

(a)

Remove the 4 screws and 6 connectors.

(b)

Remove the combination meter circuit plate from the me-
ter case.

4.

REMOVE METER HOOD

5.

REMOVE COMBINATION METER GLASS

6.

REMOVE COMBINATION METER PLATE

Remove the screw and mater plate.
7.

REMOVE SPEEDOMETER ASSEMBLY

(a)

Remove the 2 screws and speedometer assembly.

(b)

Remove the No.4 combination meter plate.

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BODY ELECTRICAL

COMBINATION METER

LEXUS RX300 (RM785E)

INSPECTION

1.

INSPECT COMBINATION METER CIRCUIT

Disconnect connector ”A” and ”B” from the combination meter
and inspect the connectors on the wire harness side as shown
in the table.

Tester connection

Condition

Specified condition

A1

Ground

Ignition switch OFF or ACC

No voltage

A1 – Ground

Ignition switch ON

Battery voltage

A3 – Ground

Constant

Battery voltage

A9 – Ground

Light control switch HI or FLASH

Battery voltage

A11 – Ground

Constant

Continuity

A12 – Ground

Light control switch TAIL or HEAD

Battery voltage

A14 – Ground

Constant

Battery voltage

Float position of fuel sender gauge Full

Resistance 4.0 Ω

A15 – Ground

Float position of fuel sender gauge 2/1

Resistance Ω

Float position of fuel sender gauge Empty

Resistance 110.0 Ω

A20 – Ground

Light control switch HI or FLASH

Continuity

A22 – Ground

Constant

Continuity

B2 – Ground

Window washer level warning switch ON

Continuity

B6

B7

Rheostat nob fully right turn

Resistance 8 – 12 κΩ

B6 – B7

Light control rheostat nob fully left turn

Resistance 0 Ω

B10 – B7

Constant

Resistance 8 – 12 κΩ

B14 – B7

Light control rheostat nob fully left turn

No continuity

If circuit is not as specified, wiring diagram and inspect the cir-
cuits connected to other parts.

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BODY ELECTRICAL

COMBINATION METER

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LEXUS RX300 (RM785E)

2.

INSPECT INSTRUMENT PANEL INTEGRATION ECU
CIRCUIT

(a)

Remove the combination meter cover.

(b)

Inspect the connectors on the ECU as follows.

Tester connection

Specified condition

E1 – A14

Continuity

E2 – A14

Continuity

E3 – A1

Continuity

E4 – A1

Continuity

E5 – C22

Continuity

E11 – A22

Continuity

E12 – A22

Continuity

E13 – A22

Continuity

E14 – A11

Continuity

F1 – C13

Continuity

F2 – C14

Continuity

F3 – C15

Continuity

F4 – C16

Continuity

F5 – C17

Continuity

F6 – C19

Continuity

F7 – C21

Continuity

F8 – A9

Continuity

F10 – A20

Continuity

F11 – B5

Continuity

F12 – A6

Continuity

F13 – B2

Continuity

F14 – A19

Continuity

If circuit is not as specified, replace the circuit plate.
3.

INSPECT COMBINATION METER ECU CIRCUIT

(a)

Remove the combination meter cover.

(b)

Inspect the connectors on the instrument panel integra-
tion ECU as follows.

Tester connection

Check indicator light circuit

Specified condition

F1 – E11, E12, E13

Right turn signal indicator light

Continuity

F2 – E11, E12, E13

Left turn signal indicator light

Continuity

F3 – E3, E4

SLIP indicator light

Continuity

F4 – E3, E4

TRC OFF indicator light

Continuity

F5 – E3, E4

CRUISE MAIN indicator light

Continuity

F6 – E3, E4

Malfunction indicator light

Continuity

F8 – F10

HI–Beam indicator light

Continuity

F12 – E3, E4

O/D OFF indicator light

Continuity

F13 – E3, E4

Washer level warning light

Continuity

F11 – E3, E4

VSC Indicator Light

Continuity

If circuit is not as specified, replace bulb or combination meter
ECU.

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A

B

C

D

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BODY ELECTRICAL

COMBINATION METER

LEXUS RX300 (RM785E)

4.

INSPECT SPEEDOMETER ON–VEHICLE

Using a speedometer tester, inspect the speedometer for allow-
able indication error and check the operation of the odometer.
HINT:
Tire wear and tire over or under inflation will increase the indica-
tion error.

(mph)

(km/h)

Standard indication

Allowable range

Standard indication

Allowable range

20

20 – 23

20

18 – 23

40

40 – 44

40

40 – 44

60

60 – 64

60

60 – 65

80

80 – 85

80

80 – 85

100

100 – 105

100

100 – 105

120

120 – 126

120

120 – 125

140

140 – 146

160

160 – 167

If error is excessive, replace the speedometer.

5.

INSPECT SPEEDOMETER RESISTANCE

(a)

Remove the meter cover, A/C and combination meter in-
tegrated ECU and combination meter circuit plate.

(b)

Measure the resistance between terminals with fixing
pointer to the stopper.

Tester connection

Resistance (Ω)

A – B

140 – 185

C – D

130 – 175

If resistance value is not as the specified, replace the meter.

6.

INSPECT TACHOMETER ON–VEHICLE

(a)

Connect a tune–up test tachometer, and start the engine.

NOTICE:

S

Reversing the connection of the tachometer will dam-
age the transistors and diodes inside.

S

When removing or installing the tachometer, be care-
ful not to drop or subject it to heavy shocks.

(b)

Compare the tester and tachometer indications.
DC 13.5 V 25

°C at (77°F)

Standard indication

Allowable range

700

630 – 770

1,000

900 – 1,100

2,000

1,850 – 2,150

3,000

2,800 – 3,200

4,000

3,800 – 4,200

5,000

4,800 – 5,200

6,000

5,750 – 6,250

7,000

6,700 – 7,300