Measuring cables in CAN-network (HS-CAN)

Fig 1: Identifying Ignition OFF

Courtesy of VOLVO CARS OF NORTH AMERICA.

• Ignition off
• Disconnect the minus terminal on the battery.
• Connect a breakout box to the Engine Control Module (ECM).
  NOTE:

  Also connect the engine control module (ECM) to the adapter cable harness, otherwise the measured values will be incorrect.

  Measure the resistance between the connections below. Due to the network design, different measurement values will be obtained. For each measurement, twist the cable harness and wiggle the connections, where accessible, to detect any intermittent short-circuits or open circuits.

  NOTE:

  The following resistance measurements only measure the main paths in the high-speed network, not the junctions that exist for some control modules. An open circuit in one path cannot be detected by this measurement. However, a short-circuit in a branch can be detected.

  Measure the resistance between #B58 (#C58) and #B45 (#C45). The resistance shall be approx. 60 Ω. Permitted values approx. 55-65 Ω.

  Also measure the resistance between each connection and the voltage as well as ground. The resistance must be infinite or very large (more than 1 MΩ).

  HINT: If a malfunction is detected, then try to separate the junction with the measured malfunction at an appropriate point further along the cable. Unplug any connector/control module nearest to the previous measurement point and measure again. In this manner, try to find the malfunction. 

  Remedy the cables as necessary.

  Other information 

  • See Battery, disconnecting
  • See Connecting the breakout box
  • See Signal description
  • See Checking wiring and terminals

Was a malfunction detected? 

• YES 

  Refer to Verification 

• NO 

  Refer to Checking the traffic load on the CAN cables