Short in CAN Bus Lines

CAN COMMUNICATION SYSTEM: Short in CAN Bus Lines

Short in CAN Bus Lines

DESCRIPTION

The CAN bus wires are considered to be shorted when the resistance between terminals 6 (CANH) and 14 (CANL) of the DLC3 is below 54 Ohms.

WIRING DIAGRAM

INSPECTION PROCEDURE
NOTE:
Before measuring the resistance, leave the vehicle as is for at least 1 minute and do not operate the engine switch, any other switches, or the doors. If any doors need to be opened in order to check connectors, open the doors and leave them open.

PROCEDURE

1. CHECK FOR SHORT IN CAN NO. 1 BUS WIRE (DLC3 BRANCH WIRE)

(a) Turn the engine switch off.
(b) Disconnect DLC3 branch wire connector E44 from the CAN No. 2 J/C "A" side (without earth terminal).
NOTICE:
- Before disconnecting the connector, make a note of where it is connected.
- Reconnect the connector to its original position.

(d) Reconnect DLC3 branch wire connector E62 to the CAN No. 2 J/C "A" side (without earth terminal).
NG -- REPAIR OR REPLACE DLC3 BRANCH WIRE OR CONNECTOR
OK -- Continue to next step.
2. CHECK FOR SHORT IN CAN NO. 1 BUS WIRE (CAN NO. 2 J/C SIDE)

(a) Disconnect CAN main bus wire connector E42 from the CAN No. 2 J/C "A" side (without earth terminal).

(b) Connect the probes of an ohmmeter to terminals 6 (CANH) and 14 (CANL) of the DLC3.
(c) Measure the resistance according to the value(s) in the table below.
Standard resistance:

OK -- CHECK FOR SHORT IN CAN NO. 1 BUS WIRE (CAN NO. 5 J/C - CAN NO. 2 J/C)
NG -- Continue to next step.
3. CHECK FOR SHORT IN CAN NO. 1 BUS WIRE (CAN NO. 2 J/C BRANCH WIRE)
(a) Reconnect CAN main bus wire connector E42 to the CAN No. 2 J/C "A" side (without earth terminal).

(b) Connect the probes of an ohmmeter to terminals 6 (CANH) and 14 (CANL) of the DLC3.
(c) While observing the resistance value shown on the tester, disconnect connectors E43, E45, E46, and E47 from the CAN No. 2 J/C one by one until the resistance becomes normal (between 54 and 69 Ohms).
HINT: Disconnect the branch wire connectors other than those of the DLC3.

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

Result:

(d) When there is a short in one or more of the branch wires:
(1) Reconnect all of the connectors to the CAN No. 2 J/C, except for the one that was disconnected last (the short-circuited bus wire). Check that the resistance shown on the tester is normal (between 54 and 69 Ohms) to confirm that there is a short in one branch wire only.
HINT:
- The connectors connected to the CAN No. 2 J/C can be distinguished according to the color of the communication bus wires and the shape of the connectors.
- Reconnecting the connectors to non-specified positions on the CAN No. 2 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.

B -- RECONNECT CONNECTOR
A -- Continue to next step.
4. CHECK FOR SHORT IN CAN NO. 1 BUS WIRE (COMBINATION METER ECU MAIN BUS WIRE)

(a) Disconnect combination meter main bus wire connector E48 from the CAN No. 2 J/C "B" side (without earth terminal).
- Before disconnecting the connector, make a note of where it is connected.
- Reconnect the connector to its original position.

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

NG -- REPLACE CAN NO. 2 J/C
OK -- Continue to next step.
5. RECONNECT CONNECTOR
(a) Reconnect combination meter main bus wire connector E48 to the CAN No. 2 J/C "B" side (without earth terminal).
NEXT -- Continue to next step.
6. CHECK FOR SHORT IN CAN NO. 1 BUS WIRE (COMBINATION METER)

(a) Disconnect combination meter connector E19.

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

HINT: If the resistance changes to 1 MOhms or more when the connector is disconnected, there may be a short in the ECM.

NG -- REPAIR OR REPLACE CAN NO. 1 BUS MAIN WIRE OR CONNECTOR (COMBINATION METER MAIN BUS WIRE)
OK -- REPLACE COMBINATION METER
7. CHECK FOR SHORT IN CAN NO. 1 BUS WIRE (CAN NO. 5 J/C - CAN NO. 2 J/C)
(a) Reconnect CAN No. 2 J/C connector E42.

(b) Disconnect CAN No. 5 J/C connector E34.

NG -- REPAIR OR REPLACE CAN NO. 1 BUS MAIN WIRE OR CONNECTOR (CAN NO. 2 J/C - CAN NO. 5 J/C)
OK -- Continue to next step.
8. CHECK FOR SHORT IN CAN NO. 1 BUS WIRE (CAN NO. 5 J/C - CAN NO. 2 J/C)
(a) Reconnect CAN No. 5 J/C connector E34.

(b) Disconnect CAN No. 5 J/C connector A26.

OK -- CHECK FOR SHORT IN CAN NO. 1 BUS WIRE (CAN NO. 5 J/C WIRE)
NG -- Continue to next step.
9. CHECK FOR SHORT IN CAN NO. 1 BUS WIRE (CAN NO. 5 J/C WIRE)
(a) Reconnect CAN No. 5 J/C connector A26.
(b) Disconnect CAN No. 5 J/C connector E34.

HINT:
- *1: with Navigation system
- *2: with dynamic radar cruise control system or pre-collision system

NG -- RECONNECT CONNECTOR
OK -- REPLACE CAN NO. 5 J/C
10. CHECK FOR SHORT IN CAN NO. 1 BUS WIRE (CAN NO. 5 J/C WIRE)
(a) Disconnect CAN No. 5 J/C connector A26.

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

Result:

B -- RECONNECT CONNECTOR
A -- REPLACE CAN NO. 5 J/C
C -- Continue to next step.
11. CHECK FOR SHORT IN CAN NO. 1 BUS WIRE (ECM MAIN BUS WIRE)

(a) Disconnect ECM connector A10.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:

HINT: Measure the resistance with CAN No. 5 J/C connector A26 disconnected.

NG -- REPAIR OR REPLACE CAN NO. 1 BUS MAIN WIRE OR CONNECTOR (ECM - CAN NO. 5 J/C)
OK -- REPLACE ECM
12. RECONNECT CONNECTOR
(a) Reconnect the connector for the short-circuited branch wire to the CAN No. 2 J/C or CAN No. 5 J/C (the connector that caused the bus wire resistance to become normal (between 54 and 69 Ohms) when it was disconnected).
NEXT -- Continue to next step.
13. CHECK FOR SHORT IN CAN NO. 1 BUS WIRE

(a) Disconnect the connector that includes terminals CANH and CANL from the ECU (or sensor) to which the short-circuited branch wire is connected. Problem Symptoms Table
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:

HINT: If the resistance becomes normal (between 54 and 69 Ohms) when the connector is disconnected from the ECU (or sensor), there may be a short in the ECU (or sensor).

NG -- REPAIR OR REPLACE CORRESPONDING ECU OR SENSOR BRANCH WIRE OR CONNECTOR
OK -- REPLACE CORRESPONDING ECU OR SENSOR