Toyota FJ Cruiser (GSJ 10, 15 series). Instruction - part 341

MULTIPLEX COMMUNICATION  –  MULTIPLEX COMMUNICATION SYSTEM

MP–5

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HOW TO PROCEED WITH 
TROUBLESHOOTING

HINT:
•

Use this procedure to troubleshoot the multiplex 
communication system.

•

The intelligent tester should be used in step 2.

NEXT

(a) Check for DTCs and note any codes that are output.
(b) Delete the DTC.
(c) Recheck for DTCs. Try to prompt the DTC by simulating 

the original activity that the DTC suggests.
Result

B

A

(a) Terminals of ECU (See page 

MP-6

).

NEXT

NEXT

NEXT

1

VEHICLE BROUGHT TO WORKSHOP

2

CHECK FOR DTC

Result

Proceed to

DTC does not recur

A

DTC recurs

B

GO TO DTC CHART

3

OVERALL ANALYSIS AND TROUBLESHOOTING

4

ADJUST, REPAIR OR REPLACE

5

CONFIRMATION TEST

END

MP–6

MULTIPLEX COMMUNICATION  –  MULTIPLEX COMMUNICATION SYSTEM

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TERMINALS OF ECU

1.

CHECK MAIN BODY ECU
(a) Disconnect the 1B, 1E, 1F, 1L and E6 main body 

ECU connectors.

1

2

3

4

5

6

11

12

13

14

15

16

7

8

9

10

17

18

19

20

1

2

3

4

5

6

9

10

11

12

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14

7

8

15

16

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2

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5

6

13

14

7

8

15

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20

9

10

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22

11

12

23

24

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5

6

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9

10

11

12

13

10

6

9

5

6

5

8

4

4

7

3

3

6

2

2

5

1

1

4

16

3

15

2

14

1

13

22

12

30

29

18

17

28

27

26

25

24

23

21

11

20

10

19

9

18

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8

7

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11

10

9

8

16

15

14

13

24

7

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26

25

24

12

11

20

23

19

21

20

19

18

22

1

2

3

4

5

6

1

2

E6

1A

1B

1D

1F

1E

1C

E7

E8

E6

1A

1B

1D

1F

1E

1C

E7

E8

Main Body ECU:

Left View:

Rear View:

B136051E02

MULTIPLEX COMMUNICATION  –  MULTIPLEX COMMUNICATION SYSTEM

MP–7

MP

1

2

4

3

1

2

3

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6

7

8

9 10 11 12 13 14

15 16

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3

19

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22

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23

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24

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10

26

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27

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28

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29

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30

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31

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32

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17

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26

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27

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28

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29

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30

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31

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32

1

2

3

4

1

13

2

14

3

15

4

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5

17

6

18

19 20

7

9

21

10

22

11

23

12

24

1

2

3

4

5

6

8

1G

1L

1K

1J

1H

1G

1H

1L

1J

1K

Main Body ECU:

Front View:

B136052E02

MP–8

MULTIPLEX COMMUNICATION  –  MULTIPLEX COMMUNICATION SYSTEM

MP

(b) Measure the voltage of the wire harness side 

connectors.

Standard voltage:

If the result is not as specified, there may be a 
malfunction on the wire harness side.

2.

CHECK BACK DOOR ECU
(a) Disconnect the S2 ECU connector.

(b) Measure the voltage of the wire harness side 

connector.

Standard voltage:

If the result is not as specified, there may be a 
malfunction on the wire harness side.

Symbols (Terminals No.)

Wiring Color

Terminal Description

Condition

Specified Condition

BECU (1B-4) - Body 

ground

W-R - Body ground

Power source (+B)

Always

11 to 14 V

BECU (1L-4) - Body 

ground

W-R - Body ground

Power source (+B)

Always

11 to 14 V

BECU (1F-12) - Body 

ground

W-R - Body ground

Power source (+B)

Always

11 to 14 V

BDR1 (1E-9) - Body 

ground

B-Y - Body ground

Power source (+B)

Always

11 to 14 V

MPX2 (E6-23) - Body 

ground

BR-R - Body ground

Multiplex communication 

signal

During communication

Signal waveform

S2

S5

B062706E01

Symbols (Terminals No.)

Wiring Color

Terminal Description

Condition

Specified Condition

GND (S2-3) - Body ground

W-B - Body ground

Ground for main power 

supply

Ground for main power 

supply

Below 1 V

BECU (S2-5) - GND (S2-

3)

W-R - W-B

Power source (+B)

Always

11 to 14 V

BDR (S2-4) - GND (S2-3)

L-O - W-B

Power source (+B)

Always

11 to 14 V

MPX2 (S2-1) - Body 

ground

BR-R - Body ground

Multiplex communication 

signal

During communication

Signal waveform

SIG (S2-6) - Body ground

B-R - Body ground

Power source (IG)

Ignition switch ON

11 to 14 V