Safety Warning

DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.

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HOMESERVICE MANUALSJEEP2009COMPASS LIMITED, ED3, FWD, AUTOMATIC CVTREPAIR AND DIAGNOSIS (SINGLE PAGE)ACCESSORIES & EQUIPMENTCOMMUNICATION DEVICESAUDIO SYSTEM (RADIO) - ELECTRICAL DIAGNOSTICSDTC TROUBLESHOOTINGU0020-CAN B BUS OFF PERFORMANCEDIAGNOSTIC TEST

2009 Jeep Compass Limited, ED3, FWD, Automatic CVT

Diagnostic Test

2009 Jeep Compass Limited, ED3, FWD, Automatic CVTSECTION Diagnostic Test

TEST FOR INTERMITTENT CONDITION
1. Turn the ignition on.
2. With the scan tool, record and erase DTCs.
3. Cycle the ignition from on to off 3 times.
4. Turn the ignition on.
5. With the scan tool, read DTCs.
  Does the scan tool display: U0020-CAN B BUS OFF PERFORMANCE?
  
  Yes
  - Go to step 2
  No
  - 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.
  - Perform the BODY VERIFICATION TEST. Refer to DTC-Based Diagnostics/MODULE, Totally Integrated Power (TIPM) - Standard Procedure .
CHECK FRONT CONTROL MODULE DTCs
1. With the scan tool, read Totally Integrated Power Module DTCs.
  Does the scan tool display any CAN B BUS DTCs - ACTIVE?
  
  Yes
  - Perform the appropriate diagnostic procedure. Refer to DTC-Based Diagnostics/MODULE, Totally Integrated Power (TIPM) - Diagnosis and Testing .
  No
  - Go to step 3
CAN B BUS (+) CIRCUIT OPEN

Fig 1: Checking CAN B BUS (+) Circuit
Courtesy of CHRYSLER LLC
1. Turn the ignition off.
2. Disconnect the Amplifier C1 harness connector.
3. Disconnect the Totally Integrated Power Module C3 harness connector.
4. 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
  - Go to step 4
  No
  - Repair the CAN B BUS (+) circuit for an open.
  - Perform the BODY VERIFICATION TEST. Refer to DTC-Based Diagnostics/MODULE, Totally Integrated Power (TIPM) - Standard Procedure .
CAN B BUS (-) CIRCUIT OPEN

Fig 2: Checking CAN B BUS (-) Circuit
Courtesy of CHRYSLER LLC
1. 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
  - Replace the Amplifier in accordance with the Service Information.
  - Perform the BODY VERIFICATION TEST. Refer to DTC-Based Diagnostics/MODULE, Totally Integrated Power (TIPM) - Standard Procedure .
  No
  - Repair the CAN B BUS (-) circuit for an open.
  - Perform the BODY VERIFICATION TEST. Refer to DTC-Based Diagnostics/MODULE, Totally Integrated Power (TIPM) - Standard Procedure .

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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.