Checking traffic load on CAN cables

Fig 1: Identifying Ignition ON

Courtesy of VOLVO CARS OF NORTH AMERICA.

• Connect the battery
• Ignition on

  Also read: Battery, disconnecting

  Faults in the CAN network may be due to a control module sending faulty messages that disrupt "normal" communication. When messages are sent incorrectly, this results in a considerable increase in the amount of traffic on the CAN network. Check the load by measuring the average voltage value on the CAN cables in relation to ground.

  Connect a voltmeter between CAN-L and ground. The voltage must be approximately 2.3 V.

  Then connect a voltmeter between CAN-H and ground. The voltage must be approximately 2.8 V.

  HINT: If possible measure from the rear of the affected connectors so that they are not damaged. 

  Fig 2: Identifying Voltage Display

  Courtesy of VOLVO CARS OF NORTH AMERICA.

Is the value OK? 

• YES 

  Refer to Fault-tracing information 

• NO 

  Refer to Identifying a control module in CAN network