LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Jeep >> 2019 >> Compass Sport, Eng CD ED6, FWD >> Repair and Diagnosis >> Restraints >> Restraints Control Systems >> (Occupant Classification Module (OCM) - Electrical Diagnostics) >> DTC Troubleshooting >> U0056-00-Can Ch Bus Off Performance >> Diagnostic Test
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Diagnostic Test

  1. ATTEMPT TO DUPLICATE THE CONDITION 
    NOTE:

    This DTC sets when the CAN C bus is disabled. If the scan tool is able to read this DTC, then the fault is currently NOT active. This diagnostic procedure only troubleshoots an intermittent condition. Follow this procedure to attempt to locate the intermittent condition or induce the fault so the diagnostic procedures under SCAN TOOL DOES NOT COMMUNICATE WITH CAN C can be followed.

    1. With the scan tool, run a Vehicle Scan Report and attached it to the repair order.
    2. With the scan tool, erase DTCs.
    3. Using the Vehicle Scan Report, along with the When Monitored and Set Conditions above, operate the vehicle in the conditions that set the DTC.

      Is the fault now present?

      NOTE:

      If the fault is present, the scan tool will not communicate with modules on the CAN C bus.

      Yes 

      No 

      • Go To  2
  2. ATTEMPT TO LOCATE AN INTERMITTENT CIRCUIT FAULT 
    NOTE:

    The scan tool LOSS OF COMM TEST will force the modules on the CAN C bus to continuously ping each other.

    1. With the scan tool, initiate the LOSS OF COMM TEST.
      NOTE:

      A value above 0 under the NUMBER OF NO RESPONSES can help indicate the location of a circuit fault while wiggling the related CAN C bus circuits.

      NOTE:

      The scan tool lag time between pings is almost 1 full second. Keep this in mind while wiggling the wires and connectors.

    2. In a systematic manner, wiggle the applicable CAN C circuits at each related module, in-line connector, and Star Connector (if equipped) while monitoring the NUMBER OF NO RESPONSES on the scan tool.

      Did the above test help locate the fault?

      Yes 

      No 

      • Go To  3
  3. PERFORM VISUAL INSPECTION OF CONNECTORS, TERMINALS AND WIRES 
    1. Disconnect all CAN C related modules harness connectors.
    2. Disconnect all related in-line harness connections.
    3. Inspect harness connectors, component connectors, and all male and female terminals for the following conditions:
      • Proper connector installation.
      • Damaged connector locks.
      • Corrosion.
      • Other signs of water intrusion.
      • Weather seal damage (if equipped).
      • Bent terminals.
      • Overheating due to a poor connection (terminal may be discolored due to excessive current draw).
      • Terminals that have been pushed back into the connector cavity.
      • Perform a terminal drag test on each connector terminal to verify proper terminal tension.

      Repair any conditions that are found.

    4. Reconnect all CAN C related modules harness connectors. Be certain that all harness connectors are fully seated and the connector locks are fully engaged.
    5. Reconnect all in-line harness connectors. Be certain that all connectors are fully seated and the connector locks are fully engaged.
    6. With the scan tool, erase DTCs.
    7. Using the Vehicle Scan Report, along with the When Monitored and Set Conditions above, operate the vehicle in the conditions that set the DTC.
    8. With the scan tool, attempt to communicate with the CAN C bus.

      Does the scan tool communicate with the CAN C bus?

      Yes 

      • The conditions that caused this DTC to set are no longer present. Test complete.

      No 

scientia non olet · About LEMON Manuals