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HOMESERVICE MANUALSJEEP2008COMPASS LIMITED, AWD, STANDARDREPAIR AND DIAGNOSIS (SINGLE PAGE)ACCESSORIES & EQUIPMENTINFOTAINMENTAUDIO SYSTEM & VIDEO SYSTEM - ELECTRICAL DIAGNOSTICSAUDIO/VIDEO SYSTEMS - ELECTRICAL DIAGNOSTICSDTC TROUBLESHOOTINGU0020-CAN B BUS OFF PERFORMANCEDIAGNOSTIC TEST
2008 Jeep Compass Limited, AWD, Standard

Diagnostic Test

2008 Jeep Compass Limited, AWD, StandardSECTION Diagnostic Test
  1. TEST FOR INTERMITTENT CONDITION 

    Turn the ignition on.

    With the scan tool, record and erase DTCs.

    Cycle the ignition from on to off 3 times.

    Turn the ignition on.

    With the scan tool, read DTCs.

    Does the scan tool display: U0020-CAN B BUS OFF PERFORMANCE? 

    Yes 

    1. Go To  2.

    No 

    1. The conditions that caused this code to set are not present at this time. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors.
    2. Perform BODY VERIFICATION TEST - VER 1 .
  2. CHECK FRONT CONTROL MODULE DTCs 

    With the scan tool, read Totally Integrated Power Module DTCs.

    Does the scan tool display any CAN B BUS DTCs - ACTIVE? 

    Yes 

    1. Refer to the symptom list for problems related to Communication in the ELECTRONIC CONTROL MODULES - ELECTRICAL DIAGNOSTICS article .

    No 

    1. Go to  3.
  3. CAN B BUS (+) CIRCUIT OPEN 
    Fig 1: Measuring Resistance Of (D55) CAN B BUS (+) Circuit Between Totally Integrated Power Module C3 Harness Connector And Amplifier C1 Harness Connector
    GC0041332Courtesy of CHRYSLER LLC

    Turn the ignition off.

    Disconnect the Amplifier C1 harness connector.

    Disconnect the Totally Integrated Power Module C3 harness connector.

    Measure the resistance of the (D55) CAN B BUS (+) circuit between the Totally Integrated Power module C3 harness connector and the Amplifier C1 harness connector.

    Is the resistance below 2.0 ohms? 

    Yes 

    1. Go To  4.
    2. Perform BODY VERIFICATION TEST - VER 1 .

    No 

    1. Repair the CAN B BUS (+) circuit for an open.
    2. Perform BODY VERIFICATION TEST - VER 1 .
  4. CAN B BUS (-) CIRCUIT OPEN 
    Fig 2: Measuring Resistance Of (D54) CAN B BUS (-) Circuit Between Totally Integrated Power Module C3 Harness Connector And Amplifier C1 Harness Connector
    GC0041333Courtesy of CHRYSLER LLC

    Measure the resistance of the (D54) CAN B BUS (-) circuit between the Totally Integrated Power Module C3 harness connector and the Amplifier C1 harness connector.

    Is the resistance below 2.0 ohms? 

    Yes 

    1. Replace the Amplifier in accordance with the service information.
    2. Perform BODY VERIFICATION TEST - VER 1 .

    No 

    1. Repair the CAN B BUS (-) circuit for an open.
    2. Perform BODY VERIFICATION TEST - VER 1 .
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.