Checking the bus wire

Fig 1: Disconnecting Connector

Courtesy of VOLVO CARS OF NORTH AMERICA.

• Disconnect the anti-lock braking system (ABS) from the bus wire, that is, disconnect connector from control unit.

  Check resistance on connector between 10 and 11 (or 19 and 20).

  NOTE:

  Be careful not to damage the connector when testing directly.

  HINT: Connect the test box only to the connector, not to the control unit. This helps to find out where a fault might be on the bus wire. 

  NOTE:

  To maintain the correct values the battery should be disconnected when measuring resistance.

  Additional information: 

  • If the vehicle has a switch button with the text "DSTC" on the center console, 19 and 20 apply instead of 10 and 11.
  • The resistance should be approximately 120 Ohms. If another value is displayed there may be an open circuit on the bus wire.
  • To connect the test box to the ABS control unit, see Connecting the ABS breakout box
  • To disconnect the battery, see Battery, disconnecting
  Fig 2: Identifying Ohm Meter

  Courtesy of VOLVO CARS OF NORTH AMERICA.

Does the measuring instrument show a resistance of approximately 120 Ohms? 

• YES 

  Refer to Replacement of ABS control unit 

• NO 

  Refer to Open-circuit in Control Area Network bus. High speed network. Permanent fault