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Home >> Jeep >> 2019 >> Renegade High Altitude, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1349 (Body Control Module (BCM) - DTCS U1411-09 To U1990-83) >> DTC Troubleshooting >> U1801-08-Lin 1-Bus Signal/Message Failure >> Diagnostic Test

Diagnostic Test

WARNING: This page is about a different car, the 2020 Jeep Renegade. However, it is still accessible from the selected car via links, so may be relevant.
  1. CHECK FOR AN ACTIVE DTC 
    1. With the scan tool, read the Body Control Module (BCM) DTCs and record on the repair order.

      Is the DTC active?

      Yes 

      • Go To  2

      No 

      • The condition or conditions that originally set this DTC are not present at this time. Using the wiring diagrams as a guide, check all related splices and connectors for signs of water intrusion, corrosion, pushed out or bent terminals and correct pin tension. If no problems are found, test complete.
      • Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  2. CHECK THE INTELLIGENT BATTERY SENSOR (IBS) FOR AN INTERNAL SHORT 
    1. Turn the ignition off.
    2. Disconnect the IBS harness connector.
    3. Turn the ignition on.
    4. Wait 10 seconds.
    5. With the scan tool, read the BCM DTCs.

      Is the DTC active?

      Yes 

      • Go To  3

      No 

  3. CHECK THE LIGHT RAIN SENSING MODULE (LRSM) FOR AN INTERNAL SHORT 
    1. Turn the ignition off.
    2. Disconnect the LRSM harness connector.
    3. Turn the ignition on.
    4. Wait 10 seconds.
    5. With the scan tool, read the BCM DTCs.

      Is the DTC active?

      Yes 

      • Go To  4

      No 

  4. CHECK THE ALARM SILENT UNIT (ASU) FOR AN INTERNAL SHORT 
    1. Turn the ignition off.
    2. Disconnect the ASU harness connector.
    3. Turn the ignition on.
    4. Wait 10 seconds.
    5. With the scan tool, read the BCM DTCs.

      Is the DTC active?

      Yes 

      • Go To  5

      No 

      • Replace the Alarm Silent Unit (ASU) in accordance with the Service Information.
      • Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  5. CHECK THE VOLTAGE STABILITY MODULE (VSM) FOR AN INTERNAL SHORT 
    1. Turn the ignition off.
    2. Disconnect the VSM harness connector.
    3. Turn the ignition on.
    4. Wait 10 seconds.
    5. With the scan tool, read the BCM DTCs.

      Is the DTC active?

      Yes 

      • Go To  6

      No 

  6. CHECK THE VOLTAGE STABILITY MODULE 2 (VSM2) FOR AN INTERNAL SHORT 
    1. Turn the ignition off.
    2. Disconnect the VSM2 harness connector.
    3. Turn the ignition on.
    4. Wait 10 seconds.
    5. With the scan tool, read the BCM DTCs.

      Is the DTC active?

      Yes 

      • Go To  7

      No 

  7. CHECK THE (D401) LIN BUS 1 CIRCUIT FOR A SHORT TO VOLTAGE 
    1. Turn the ignition off.
    2. Disconnect the BCM C4 harness connector.
    3. Disconnect the BCM C6 harness connector.
    4. Turn the ignition on.
    5. Measure the voltage on the (D401) LIN Bus 1 circuit at the BCM C4 harness connector.
    6. Measure the voltage on the (D401) LIN Bus 1 circuit at the BCM C6 harness connector.

      Is there any voltage present at either connection?

      Yes 

      • Repair the short to voltage on the (D401) LIN Bus 1 circuit.
      • Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .

      No 

      • Go To  8
  8. CHECK THE (D401) LIN BUS 1 CIRCUIT FOR A SHORT TO GROUND 
    1. Turn the ignition off.
    2. Check for continuity between ground and the (D401) LIN Bus 1 circuit at the BCM C4 harness connector.
    3. Check for continuity between ground and the (D401) LIN Bus 1 circuit at the BCM C6 harness connector.

      Is there continuity between ground and the (D401) LIN Bus 1 circuit?

      Yes 

      • Repair the short to ground in the (D401) LIN Bus 1 circuit.
      • Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .

      No 

      • Go To  9
  9. 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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