Can Communication. Can Communication System (For Rhd) Short In Can Bus Lines

Symptom	Trouble Area
The resistance between terminals 6 (CANH) and 14 (CANL) of the DLC3 is below 54 Ω.	Short in CAN bus lines Skid control ECU Steering angle sensor Yaw rate sensor ECM Gateway ECU Seat belt control ECU Distance control ECU Power steering ECU Television camera ECU Center airbag sensor CAN LH J/C CAN RH J/C

WIRING DIAGRAM

Lexus Is250, Is220D. Gse20 Ale20.Can Communication.Can Communication System (For Lhd).Can Communication System (For Rhd) Short In Can Bus Lines

INSPECTION PROCEDURE

1.CHECK FOR SHORT IN CAN BUS LINES (DLC3 BRANCH LINE)

Disconnect the DLC3 branch line connector (J94) from the CAN RH J/C A side (with earth terminal).
NOTICE:
1. Before disconnecting the connector, make a note of where it is connected.
2. Reconnect the connector to its original position.

Measure the resistance according to the value(s) in the table below.
Standard resistance:
Tester Connection
Condition
Specified Value
J21-6 (CANH) - J21-14 (CANL)
Engine switch off
1 MΩ or higher

REPAIR OR REPLACE DLC3 BRANCH LINE OR CONNECTOR

OK

2.RECONNECT CONNECTOR

Reconnect the DLC3 branch line connector (J94) to the CAN RH J/C A side (with earth terminal) .

NEXT

3.CHECK FOR SHORT IN CAN BUS LINES (BRANCH LINE)

Connect the probes of an ohmmeter to terminals 6 (CANH) and 14 (CANL) of the DLC3.

While observing the resistance value shown on the tester, disconnect connectors J1, J3, J4, J5, J8, J82, J96, and J97 from the CAN LH J/C or CAN RH J/C one by one until the resistance becomes normal (between 54 and 69 Ω).

HINT:

Disconnect the branch line connectors other than those of the DLC3.

Wiring color:
CAN LH J/C A Side (with Earth Terminal)	Code	Color (CANH Side)	Color (CANL Side)
Power steering ECU	J1	P	W
ECM	J2	B	W
Seat belt control ECU	J3	V	W
Center airbag sensor	J4	R	W

Wiring color:
CAN LH J/C B Side (without Earth Terminal)	Code	Color (CANH Side)	Color (CANL Side)
Yaw rate sensor	J5	P	W
CAN main bus line (bus line connecting CAN LH J/C and CAN RH J/C)	J7	B	W
Television camera ECU	J8	L	W

Wiring color:
CAN RH J/C A Side (with Earth Terminal)	Code	Color (CANH Side)	Color (CANL Side)
CAN main bus line (bus line connecting CAN RH J/C and CAN LH J/C)	J81	B	W
Steering angle sensor	J82	P	W
DLC3	J94	G	W
Skid control ECU	J96	R	W

Wiring color:
CAN RH J/C B Side (without Earth Terminal)	Code	Color (CANH Side)	Color (CANL Side)
Gateway ECU	J84	B	W
Distance control ECU	J97	GR	W

NOTICE:

Do not reconnect the disconnected connectors until this inspection is complete because there may be a short in 2 or more branch lines.

Result:

Symptom	Proceed to
The resistance is still below 54 Ω when all the specified connectors are disconnected. (There are no shorts in the branch lines.)	A
The resistance becomes normal (between 54 and 69 Ω) when a connector is disconnected. (There is a short in one or more of the branch lines.)	B

When there is a short in one or more of the branch lines:
1. Reconnect all of the connectors to the CAN J/C, except for the one that was disconnected last (the short-circuited bus line). Check that the resistance shown on the tester is normal (between 54 and 69 Ω) to confirm that there is a short in the one branch line only.
  HINT:
  1. The connectors connected to the CAN J/C can be distinguished according to the color of the communication bus lines and the shape of the connectors.
  2. Reconnecting the connectors to non-specified positions on the CAN J/C does not affect system operation. However, it is preferred to reconnect the connectors to their specified positions to avoid negative effects on the wiring such as tension on the wiring harnesses, and to make future maintenance easier.

Go to step 9

A

4.CHECK FOR SHORT IN CAN BUS LINES (GATEWAY ECU MAIN BUS LINE)

Disconnect the gateway ECU main bus line connector (J84) from the CAN RH J/C B side (without earth terminal) .
NOTICE:
1. Before disconnecting the connector, make a note of where it is connected.
2. Reconnect the connector to its original position.

Measure the resistance according to the value(s) in the table below.

Standard resistance:

Tester Connection	Condition	Specified Value
J21-6 (CANH) - J21-14 (CANL)	Engine switch off	108 to 132 Ω

Result:

Symptom	Proceed to
The resistance is still below 54 Ω when the gateway ECU connector is disconnected. (There are no shorts in the gateway ECU main bus lines.)	A
The resistance falls within the specified range (between 108 and 132 Ω) (either of the terminating resistances is normal) when the gateway ECU connector is disconnected. (There is a short in the gateway ECU main bus lines.)	B

Go to step 11

A

5.CHECK FOR SHORT IN CAN BUS LINES (ECM MAIN BUS LINE)

Disconnect the ECM main bus line connector (J2) from the CAN LH J/C A side (with earth terminal) .
NOTICE:
1. Before disconnecting the connector, make a note of where it is connected.
2. Reconnect the connector to its original position.

Measure the resistance according to the value(s) in the table below.

Standard resistance:

Tester Connection	Condition	Specified Value
J21-6 (CANH) - J21-14 (CANL)	Engine switch off	1 MΩ or more

HINT:

Measure the resistance with the gateway ECU main bus line connector (J84) disconnected.

Result:

Symptom	Proceed to
The resistance is still below 1 MΩ when the ECM connector is disconnected. (There are no shorts in the ECM main bus lines.)	A
The resistance becomes 1 MΩ or more when the ECM connector is disconnected. (There is a short in the ECM main bus lines.)	B

Go to step 13

A

6.CHECK CAN RH J/C

Disconnect the CAN main bus line connector (J81) from the CAN RH J/C A side (with earth terminal) .
NOTICE:
1. Before disconnecting the connector, make a note of where it is connected.
2. Reconnect the connector to its original position.

Measure the resistance according to the value(s) in the table below.
Standard resistance:
Tester Connection
Condition
Specified Value
J21-6 (CANH) - J21-14 (CANL)
Engine switch off
1 MΩ or more

REPLACE CAN RH J/C

OK

7.RECONNECT CONNECTOR

Reconnect the CAN main bus line connector (J81) to the CAN RH J/C A side (with earth terminal).

NEXT

8.CHECK CAN LH J/C

Disconnect the CAN main bus line connector (J7) from the CAN LH J/C B side (without earth terminal) .
NOTICE:
1. Before disconnecting the connector, make a note of where it is connected.
2. Reconnect the connector to its original position.

Measure the resistance according to the value(s) in the table below.
Standard resistance:
Tester Connection
Condition
Specified Value
J21-6 (CANH) - J21-14 (CANL)
Engine switch off
1 MΩ or higher

REPLACE CAN LH J/C

REPAIR OR REPLACE CAN MAIN BUS LINE (CAN LH J/C - CAN RH J/C)

9.RECONNECT CONNECTOR

Reconnect the connector for the short-circuited branch line to the CAN J/C (the connector that caused the bus line resistance to become normal (between 54 and 69 Ω) when it was disconnected).

NEXT

10.CHECK FOR SHORT IN CAN BUS LINES

Disconnect the connector that includes terminals CANH and CANL from the ECU (or sensor) to which the short-circuited branch line is connected. (Click here)

Measure the resistance according to the value(s) in the table below.
Standard resistance:
Tester Connection
Condition
Specified Value
J21-6 (CANH) - J21-14 (CANL)
Engine switch off
1 MΩ or higher
HINT:
If the resistance becomes normal (between 54 and 69 Ω) when the connector is disconnected from the ECU (or sensor), there may be a short in the ECU (or sensor).

REPAIR OR REPLACE CORRESPONDING ECU OR SENSOR BRANCH LINE OR CONNECTOR

REPLACE CORRESPONDING ECU OR SENSOR

11.RECONNECT CONNECTOR

Reconnect the gateway ECU main bus line connector (J84) to the CAN RH J/C B side (without earth terminal) .

NEXT

12.CHECK FOR SHORT IN CAN BUS LINES (GATEWAY ECU)

Disconnect the gateway ECU connector (J76).

Measure the resistance according to the value(s) in the table below.
Standard resistance:
Tester Connection
Condition
Specified Value
J21-6 (CANH) - J21-14 (CANL)
Engine switch off
108 to 132 Ω
HINT:
If the resistance becomes normal (between 108 to 132 Ω) when the connector is disconnected, there may be a short in the gateway ECU.

REPAIR OR REPLACE CAN MAIN BUS LINE (GATEWAY ECU MAIN BUS LINE)

REPLACE GATEWAY ECU

13.RECONNECT CONNECTOR

Reconnect the ECM main bus line connector (J2) to the CAN LH J/C A side (with earth terminal) .

NEXT

14.CHECK FOR SHORT IN CAN BUS LINES (ECM)

Disconnect the ECM connector (A5).

Measure the resistance according to the value(s) in the table below.
Standard resistance:
Tester Connection
Condition
Specified Value
J21-6 (CANH) - J21-14 (CANL)
Engine switch off
1 MΩ or higher
HINT:
1. Measure the resistance with the gateway ECU main bus line connector (J84) disconnected.
2. If the resistance changes to 1 MΩ or more when the connector is disconnected, there may be a short in the ECM.

REPAIR OR REPLACE CAN MAIN BUS LINE (ECM MAIN BUS LINE)

REPLACE ECM