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Home >> Alfa Romeo >> 2019 >> Giulia Base, AWD >> Repair and Diagnosis >> Accessories & Equipment >> Communication Devices >> Body Control Module (BCM) - DTCS B12AE-15 To U1702-87 >> DTC Troubleshooting >> U0001-87-C1 Can Bus-Missing Message - With Security Gateway (SGW) >> Diagnostic Test

Diagnostic Test

  1. CHECK FOR AN ACTIVE DTC 
    NOTE:

    If the scan tool will not communicate with the vehicle, proceed to SCAN TOOL DOES NOT COMMUNICATE WITH VEHICLE. Refer to DIAGNOSIS AND TESTING .

    NOTE:

    Disconnecting the Radio Frequency (RF) Hub Module or Body Control Module (BCM) may result in a loss of ignition status messages and may cause scan tool communication concerns.

    NOTE:

    With a scan tool, refer to the Network Review screen to aid in identifying vehicle communication problems. The screen depicts a high level view of the vehicle network and any controllers reporting communication problems will appear in red.

    1. Turn the ignition on.
    2. With the scan tool, read the Body Control Module (BCM) DTCs and record on the repair order.
    3. With the scan tool, erase the BCM DTCs.
    4. Turn the ignition off and wait 10 seconds.
    5. Turn the ignition on.
    6. With the scan tool, read the BCM DTCs.

      Did the DTC return?

      Yes 

      • Go To  2

      No 

  2. CHECK THE (D1) CAN C1 BUS (+) CIRCUIT FOR A SHORT TO VOLTAGE 
    1. Turn the ignition off.
    2. Disconnect the scan tool.
    3. Disconnect the Security Gateway (SGW) Module C1 harness connector.
    4. Turn the ignition on.
    5. Measure the voltage on the (D1) CAN C1 Bus (+) circuit at the Security Gateway (SGW) Module C1 harness connector, terminal 5.

      Is the voltage above 10.0 volts?

      Yes 

      • A short to voltage on the (D1) CAN C1 Bus (+) circuit is present. Disconnect each module, one at a time, to assist in determining the location of the concern. Repair the circuit or replace the module, that when disconnected, allowed the CAN C1 Bus (+) voltage to return to normal.
      • Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .

      No 

      • Go To  3
  3. CHECK THE (D2) CAN C1 BUS (-) CIRCUIT FOR A SHORT TO VOLTAGE 
    1. Measure the voltage on the (D2) CAN C1 Bus (-) circuit at the Security Gateway (SGW) Module C1 harness connector, terminal 12.

      Is the voltage above 10.0 volts?

      Yes 

      • A short to voltage on the (D2) CAN C1 Bus (-) circuit is present. Disconnect each module, one at a time, to assist in determining the location of the concern. Repair the circuit or replace the module, that when disconnected, allowed the CAN C1 Bus (-) voltage to return to normal.
      • Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .

      No 

      • Go To  4
  4. CHECK THE (D1) CAN C1 BUS (+) CIRCUIT FOR A SHORT TO GROUND 
    1. Turn the ignition off.
    2. Disconnect and isolate the negative battery cable.
    3. If equipped with Engine Stop Start (ESS), disconnect and isolate the negative auxiliary battery cable.
    4. Check for continuity between ground and the (D1) CAN C1 Bus (+) circuit at the Security Gateway (SGW) Module C1 harness connector, terminal 5.

      Is there continuity between ground and the (D1) CAN C1 Bus (+) circuit?

      Yes 

      • A short to ground on the (D1) CAN C1 Bus (+) circuit is present. Disconnect each module, one at a time, to assist in determining the location of the concern. Repair the circuit or replace the module, that when disconnected, allowed the CAN C1 Bus (+) resistance to return to normal.
      • Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .

      No 

      • Go To  5
  5. CHECK THE (D2) CAN C1 BUS (-) CIRCUIT FOR A SHORT TO GROUND 
    1. Check for continuity between ground and the (D2) CAN C1 Bus (-) circuit at the Security Gateway (SGW) Module C1 harness connector, terminal 12.

      Is there continuity between ground and the (D2) CAN C1 Bus (-) circuit?

      Yes 

      • A short to ground on the (D2) CAN C1 Bus (-) circuit is present. Disconnect each module, one at a time, to assist in determining the location of the concern. Repair the circuit or replace the module, that when disconnected, allowed the CAN C1 Bus (-) resistance to return to normal.
      • Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .

      No 

      • Go To  6
  6. CHECK FOR CORRECT CAN C1 BUS TERMINATION RESISTANCE 
    1. Measure the resistance between the (D1) CAN C1 Bus (+) circuit and the (D2) CAN C1 Bus (-) circuit at Security Gateway (SGW) Module C1 harness connector terminals 5 and 12.

      Is the resistance below 53.5 Ohms?

      Yes 

      • A short between the (D1) CAN C1 Bus (+) circuit and the (D2) CAN C1 Bus (-) is present. Diagnose the short between the (D1) CAN C1 Bus (+) circuit and the (D2) CAN C1 Bus (-) circuit. Disconnect each module, one at a time, to assist in determining the location of the concern. Repair the circuit or replace the module, that when disconnected, allowed the CAN C1 Bus resistance to return to normal.
      • Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .

      No 

      • Go To  7
  7. CHECK RELATED HARNESS CONNECTIONS 
    1. Disconnect all BCM harness connectors.
    2. Disconnect all related in-line harness connections (if equipped).
    3. Disconnect the related component harness connectors.
    4. 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.

    5. Reconnect all BCM harness connectors. Be certain that all harness connectors are fully seated and the connector locks are fully engaged.
    6. Reconnect all in-line harness connectors (if equipped). Be certain that all connectors are fully seated and the connector locks are fully engaged.
    7. Reconnect all related component harness connectors. Be certain that all connectors are fully seated and the connector locks are fully engaged.
    8. With the scan tool, erase DTCs.
    9. Using the recorded Environmental Data, along with the When Monitored and Set Conditions above, operate the vehicle in the conditions that set the DTC.
    10. With the scan tool, read BCM DTCs.

      Did the DTC return?

      Yes 

      No 

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