Toyota FJ Cruiser (GSJ 10, 15 series). Instruction - part 343

MULTIPLEX COMMUNICATION  –  MULTIPLEX COMMUNICATION SYSTEM

MP–13

MP

OK:

Neither DTC B1214 nor DTC B1215 is output.

NOTICE:
Disconnect the connector in the operational 
sequence, and start the next step after the connector 
is reconnected.

OK

NG

(a) Check for a short-circuit in B+ or body ground.

Main Body ECU

Back Door ECU

MPX2

MPX2

B137555E01

REPLACE BACK DOOR ECU

2

CHECK HARNESS AND CONNECTOR (MAIN BODY ECU - BACK DOOR ECU)

Main Body ECU

Back Door ECU

MPX2

MPX2

B137554E01

MP–14

MULTIPLEX COMMUNICATION  –  MULTIPLEX COMMUNICATION SYSTEM

MP

(b) Disconnect the S2 back door ECU connector and E6 

main body ECU connector.
(1) Measure the voltage between the terminals of the 

S2 back door ECU or E6 main body ECU connector 
and body ground.

Standard voltage

(2) Check the resistance.

Standard resistance

(c) Reconnect the back door ECU connector and main body 

ECU connector.

NG

OK

23

22

26

18

10

25

13 14

16 17

19 20

11 12

15

24

27

30

29

28

21

1

2

3

4

5

6

7

8

9

1

8

7

6

5

4

3

2

Wire Harness Side:

Back Door ECU

Main Body ECU

S2

E6

MPX2

MPX2

Front View

Front View

B137571E03

Tester Connection

Condition

Specified Condition

E6-23 (MPX2) or S2-1 (MPX2) - Body 

ground

Ignition switch ON

Below 1 V

Tester Connection

Specified Condition

E6-23 (MPX2) or S2-1 (MPX2) - Body ground

10 k

Ω or higher

REPAIR OR REPLACE WIRE HARNESS 
BETWEEN MAIN BODY ECU AND BACK 
DOOR ECU

REPLACE MAIN BODY ECU

MULTIPLEX COMMUNICATION  –  MULTIPLEX COMMUNICATION SYSTEM

MP–15

MP

DESCRIPTION

DTC B1287 is output when communication between the back door ECU and the main body ECU stops for 
more than 10 seconds.

WIRING DIAGRAM

DTC

B1287

Back Door ECU Communication Stop

DTC No.

DTC Detection Condition

Trouble Area

B1287

Back door ECU communication stops

•

Back door ECU

•

Wire harness

POWER

Back Door ECU

Main Body ECU

J/B

ALT

Short 
Pin

ECU-B

Battery

BDR

BECU

GND

MPX2

MPX2

B137552E01

MP–16

MULTIPLEX COMMUNICATION  –  MULTIPLEX COMMUNICATION SYSTEM

MP

INSPECTION PROCEDURE

(a) Disconnect the E6 main body ECU and S2 back door 

ECU connectors.

(b) Check the resistance.

Standard resistance

(c) Reconnect the main body ECU and back door ECU 

connectors.

NG

OK

(a) Disconnect the S2 back door ECU connector.
(b) Measure the voltage between the terminals of the S2 

back door ECU connector and body ground.
Standard voltage

(c) Reconnect the ECU connector.

NG

1

CHECK COMMUNICATION LINE

23

22

26

18

10

25

13 14

16 17

19 20

11 12

15

24

27

30

29

28

21

1

2

3

4

5

6

7

8

9

1

8

7

6

5

4

3

2

Wire Harness Side:

Back Door ECU

Main Body ECU

S2

E6

MPX2

MPX2

Front View

Front View

B137571E03

Tester Connection

Specified Condition

E6-23 (MPX2) - S2-1 (MPX2)

Below 1 

Ω

REPAIR OR REPLACE HARNESS OR 
CONNECTOR

2

CHECK BACK DOOR ECU (POWER SOURCE)

1

8

7

6

5

4

3

2

Wire Harness Side:

Back Door ECU

BECU

S2

Front View

B137572E01

Tester Connection

Specified Condition

S2-5 (BECU) - Body ground

11 to 14 V

REPAIR OR REPLACE HARNESS OR 
CONNECTOR