DESCRIPTION
There may be a short circuit between one of the CAN bus lines and +B when no resistance exists between terminal 18 (CA4H) of the network gateway ECU and terminal 16 (BAT) of the DLC3, or terminal 17 (CA4L) of the network gateway ECU and terminal 16 (BAT) of the DLC3.
Symptom | Trouble Area |
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No resistance exists between terminal 18 (CA4H) of the network gateway ECU and terminal 16 (BAT) of the DLC3, or terminal 17 (CA4L) of the network gateway ECU and terminal 16 (BAT) of the DLC3. |
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WIRING DIAGRAM
CAUTION / NOTICE / HINT
Note
Before measuring the resistance of the CAN bus, turn the engine switch off and leave the vehicle for 1 minute or more without operating the key or any switches, or opening or closing the doors. After that, disconnect the cable from the negative (-) battery terminal and leave the vehicle for 1 minute or more before measuring the resistance.
After turning the engine switch off, waiting time may be required before disconnecting the cable from the negative (-) battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) battery terminal notices before proceeding with work.
Because the order of diagnosis is important to allow correct diagnosis, make sure to begin troubleshooting using How to Proceed with Troubleshooting when CAN communication system related DTCs are output.
After performing repairs, perform the DTC check procedure and confirm that the DTCs are not output again.
DTC check procedure: Drive the vehicle at a speed of 60 km/h (37 mph) or more for 5 minutes or more, and with the dynamic radar cruise control system operated for 3 seconds or more.
After the repair, perform the CAN bus check and check that all the ECUs and sensors connected to the CAN communication system are displayed.
Tech Tips
Operating the engine switch, any other switches or a door triggers related ECU and sensor communication on the CAN. This communication will cause the resistance value to change.
Even after DTCs are cleared, if a DTC is stored again after driving the vehicle for a while, the malfunction may be occurring due to vibration of the vehicle. In such a case, wiggling the ECUs or wire harness while performing the inspection below may help determine the cause of the malfunction.
PROCEDURE
CHECK FOR SHORT TO +B IN CAN BUS LINE (NETWORK GATEWAY ECU)
Disconnect the cable from the negative (-) battery terminal.
Disconnect the J75 network gateway ECU connector.
*1 | DLC3 | - | - |
*a | Front view of wire harness connector (to Network Gateway ECU) |
- | - |
Measure the resistance according to the value(s) in the table below.
Standard Resistance | |||||||
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Result | ||||||||
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A |
REPLACE NETWORK GATEWAY ECU Click here |
C |
CHECK FOR SHORT TO +B IN CAN BUS LINE (NO. 7 CAN JUNCTION CONNECTOR) Click here |
B |
CHECK FOR SHORT TO +B IN CAN BUS LINE (ECM)
Reconnect the J75 network gateway ECU connector.
*1 | DLC3 |
*a | Front view of wire harness connector (to ECM) |
Disconnect the A37 ECM connector.
Measure the resistance according to the value(s) in the table below.
Standard Resistance | |||||||
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Result | |||
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OK |
REPLACE ECM Click here |
NG |
REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (NETWORK GATEWAY ECU - ECM) |
CHECK FOR SHORT TO +B IN CAN BUS LINE (NO. 7 CAN JUNCTION CONNECTOR)
Reconnect the J75 network gateway ECU connector.
Disconnect the J99 No. 7 CAN junction connector.
Measure the resistance according to the value(s) in the table below.
*1 | DLC3 | - | - |
*a | Front view of wire harness connector (to No. 7 CAN Junction Connector) |
*b | to Engine Stop and Start ECU |
*c | to ECM | *d | to Network Gateway ECU |
Standard Resistance | |||||||||||||||||||
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Result | ||||||||
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A |
REPLACE NO. 7 CAN JUNCTION CONNECTOR |
B |
REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (NETWORK GATEWAY ECU - NO. 7 CAN JUNCTION CONNECTOR) |
C |
CHECK FOR SHORT TO +B IN CAN BUS LINE (ECU, SENSOR)
Reconnect all wire harness connectors.
Disconnect the connector that includes terminals CANH and CANL from the ECU or sensor to which the bus line shorted to +B is connected.
Measure the resistance according to the value(s) in the table below.
*1 | DLC3 | - | - |
*a | Component with harness connected (Network Gateway ECU) |
- | - |
Standard Resistance | |||||||
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Tech Tips
If the resistance changes to 6 kΩ or higher when the connector is disconnected from the ECU or sensor, there may be a short in the ECU or sensor.
Result | |||
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OK |
REPLACE CORRESPONDING ECU OR SENSOR |
NG |
REPAIR OR REPLACE CORRESPONDING ECU OR SENSOR CAN BUS LINE OR CONNECTOR |