Short to B+ in CAN Bus Line

CAN COMMUNICATION: CAN COMMUNICATION SYSTEM: Short to B+ in CAN Bus Line
- Short to B+ in CAN Bus Line

DESCRIPTION

A short to B+ is suspected in the CAN bus wire when the resistance between terminals 6 (CANH) and 16 (BAT), or terminals 14 (CANL) and 16 (BAT) of the DLC3 is below 6 kOhms.

WIRING DIAGRAM

INSPECTION PROCEDURE

NOTICE:
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 TO B+ 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 (with earth terminal).

NOTICE:
* Before disconnecting the connector, make a note of where it is connected.
* Reconnect the connector to its original position.

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

Standard resistance:

(d) Reconnect DLC3 branch wire connector E44 to the CAN No. 2 J/C "A" side (with earth terminal).

NG -- REPAIR OR REPLACE DLC3 BRANCH WIRE OR CONNECTOR
OK -- Continue to next step.

2. CHECK FOR SHORT TO B+ 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 (with earth terminal).

(b) Using an ohmmeter, measure the resistance between terminals 6 (CANH) and 16 (BAT), and between terminals 14 (CANL) and 16 (BAT) of the DLC3 each time a connector is disconnected.

Standard resistance:

OK -- CHECK FOR SHORT TO B+ IN CAN NO. 1 BUS WIRE
NG -- Continue to next step.

3. CHECK FOR SHORT TO B+ IN CAN NO. 1 BUS WIRE

(a) Disconnect connectors from the CAN No. 2 J/C one at a time.

HINT
Disconnect the ECU and sensor connectors other than the DLC3 branch wires and CAN main bus wires between the CAN No. 2 J/C and CAN No. 5 J/C.

(b) Using an ohmmeter, measure the resistance between terminals 6 (CANH) and 16 (BAT), and between terminals 14 (CANL) and 16 (BAT) of the DLC3 each time a connector is disconnected.

NOTICE:
Do not reconnect the disconnected connectors until this inspection is complete because there may be a short to B+ in 2 or more CAN bus wires.

Result:

(c) When there is a short to B+ in one or more of the bus wires that connect to an ECU (or sensor):

(1) Reconnect all of the connectors to the CAN No. 2 J/C, except for the one that was disconnected last (the bus wire that is shorted to B+). Check that the resistance shown on the tester is normal (6 kOhms or higher) to confirm that there is a short to B+ in one bus 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 -- REPLACE CAN NO. 2 J/C

4. CHECK FOR SHORT TO B+ IN CAN NO. 1 BUS 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:

OK -- CHECK FOR SHORT TO B+ IN CAN NO. 1 BUS WIRE (CAN NO. 5 J/C WIRE)
NG -- Continue to next step.

5. CHECK FOR SHORT TO B+ 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.

Standard resistance:

HINT
* *1: w/ Navigation system
* *2: w/ Dynamic radar cruise control system or HID head light type
* *3: w/o Navigation system with multi-display

Result:

B -- RECONNECT CONNECTOR

C -- REPAIR OR REPLACE CAN NO. 1 BUS MAIN WIRE OR CONNECTOR (CAN NO. 2 J/C - CAN NO. 5 J/C)

A -- REPLACE CAN NO. 5 J/C

6. CHECK FOR SHORT TO B+ 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:

OK -- REPLACE CAN NO. 5 J/C
NG -- Continue to next step.

7. RECONNECT CONNECTOR

(a) Reconnect the connector of the bus wire that is shorted to B+ to the CAN No. 2 J/C or CAN No. 5 J/C (the connector that caused the bus wire resistance to change to 6 kOhms or more when it was disconnected).

NEXT -- Continue to next step.

8. CHECK FOR SHORT TO B+ IN CAN NO. 1 BUS WIRE

(a) Disconnect the connector that includes terminals CANH and CANL from the ECU (or sensor) to which the bus wire shorted to B+ is connected. Symptom Related Diagnostic Procedures

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

Standard resistance:

HINT
If the resistance changes to 6 kOhms or higher 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