Checking A Short-Circuit In CAN Cables

Connect an ohmmeter between the relevant CAN cable (CAN-L and CAN-H) and the power supply, and between the CAN cable and ground. Twist the connectors and turn the cable harness to different positions at each reading to determine any intermittent short-circuits.

Take the following readings: 

• The resistance between CAN-L and ground
• The resistance between CAN-L and voltage
• The resistance between CAN-H and ground
• The resistance between CAN-H and voltage

The resistance must be infinite or very high in all cases (greater than 1 MΩ).

HINT: The reading can be taken from the same connector if the CAN cables, power supply and ground are exposed. If possible, take readings on the rear of the connector to prevent damage to the terminals in the connector. If this is not possible, use the adapter wiring or loose terminal pins to obtain a good contact. 

Fig 1: Identifying Ohmmeter

Courtesy of VOLVO CARS OF NORTH AMERICA.

Was a fault detected? 

• YES 

  Refer to Identifying Fault Causes In The CAN Network 

• NO 

  Refer to Checking The Traffic Load On The CAN Cables