Lexus RX300 (MCU15). Manual — part 117

I04481

S Engine Room Junction Block

S Fusible Link Block (Inside Engine Room Junction Block)

Fuse

Relay

1. –

2. H–LP R LWR Fuse

3. H–LP L LWR Fuse

4. HAZARD Fuse

5. AM2 Fuse

6. TEL Fuse

7. FL DOOR Fuse

8. SHORT PIN

9. ALT–S Fuse

10. HORN Fuse

11. EFI Fuse

12. DOME Fuse

13. ECU–B Fuse

14. RAD No. 1 Fuse

15. –

16. –

17. –

18. MAIN M–Fuse

A. Headlight Control Relay

B. Starter Relay

C. RR DEF Relay

D. MG CLT Relay

E. HORN Relay

F. EFI Relay

Fuse

1. ABS H–Fuse

2. ALT H–Fuse

3. RDI FAN M–Fuse

4. CDS FAN M–Fuse

5. RR DEF M–Fuse

6. HEATER M–Fuse

–

BODY ELECTRICAL

POWER SOURCE

BE–15

LEXUS RX300 (RM785E)

I04480

Fuse

1. AM1 M–Fuse

2. POWER M–Fuse

3. IGN Fuse

4. RADIO No. 2 Fuse

5. CIG Fuse

6. D RR DOOR Fuse

7. PWR OUTLET Fuse

8. FR FOG Fuse

9. SRS–IG Fuse

10. ECU IG Fuse

11. WIPER Fuse

12. P RR DOOR Fuse

13. P FR DOOR Fuse

14. S/ROOF Fuse

15. HEATER Fuse

16. GAUGE Fuse

17. RR WIP Fuse
18. STOP Fuse

19. ODB Fuse

20. SEAT HTR Fuse

21. STARTER Fuse
22. WASHER Fuse

24. FR DEF Fuse

25. SRS–B Fuse
26. TAIL Fuse

S Instrument Panel Junction Block

27. PANEL Fuse

Relay

A. Taillight Control Relay

B. Fog Light Relay

C. ACC Relay

23. RR FOG Fuse

BE–16

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BODY ELECTRICAL

POWER SOURCE

LEXUS RX300 (RM785E)

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S Relay Block No. 1

Relay

A. Circuit Opening Relay

B. Rear Fog Light Relay

C. Mirror Heater Relay

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BODY ELECTRICAL

POWER SOURCE

BE–17

LEXUS RX300 (RM785E)

The power source supplies power to each of the vehicle’s electrical devices. It is composed of the battery,
fuses and relays, which are located centrally at engine room junction block, engine room No. 1 relay block,
fusible link block and engine room No. 2 relay block in the engine compartment, and instrument panel junc-
tion block in the cabin near the driver’s feet.

BE0U8–02

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BE–18

–

BODY ELECTRICAL

POWER SOURCE

LEXUS RX300 (RM785E)

INSPECTION

1.

INSPECT ENGINE ROOM JUNCTION BLOCK CIRCUIT

(a)

Remove the fuse from the junction block and inspect the connection on the junction block side.

Fuse

Tester connection

Condition

Specified condition

MAIN

2 – Ground

Constant

Battery voltage

H–LP R LWR

3 – Ground

Light control switch HEAD and headlight dimmer

switch LOW beam

Battery voltage

H–LP L LWR

6 – Ground

Light control switch HEAD and headlight dimmer

switch LOW beam

Battery voltage

HAZARD

8 – Ground

Constant

Battery voltage

AM2

9 – Ground

Constant

Battery voltage

TEL

12 – Ground

Constant

Battery voltage

FL DOOR

13 – Ground

Constant

Battery voltage

ALT–S

17 – Ground

Constant

Battery voltage

HORN

20 – Ground

Constant

Battery voltage

EFI

21 – Ground

Constant

Battery voltage

DOME

24 – Ground

Constant

Battery voltage

ECU–B

26 – Ground

Constant

Battery voltage

RAD No.1

27 – Ground

Constant

Battery voltage

If the circuit is as specified, inspect the circuits connected to other parts.
(b)

Remove the relay from the junction block and inspect the connector on the junction block side.

Relay

Tester connection

Condition

Specified condition

HEAD LAMP

29 – Ground

31 – Ground

32 – Ground

Constant

Light control switch HEAD

Constant

Battery voltage

Continuity

Battery voltage

Starter

33 – Ground

34 – Ground

IG switch START and PNP switch P or N position

Constant

Battery voltage

Continuity

Starter

36 – Ground

Constant

Battery voltage