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Home >> Fiat >> 2016 >> 500 Turbo, Standard Trans >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 13 (Body Control Module (BCM) - DTCS B226A-00 To U1493-00 - 500 - Electric) >> DTC Troubleshooting >> U0020-88-Can B Bus Off Performance - Bus Off >> Diagnostic Test

Diagnostic Test

WARNING: This page is about a different variant/trim than selected.
  1. CHECK FOR AN ACTIVE DTC 
    NOTE:

    Check for any Technical Service Bulletins (TSBs) related to the condition. If a TSB applies, perform the procedure outlined in the TSB before continuing.

    1. Turn the ignition on.
    2. With the scan tool, read DTCs.

      Does the scan tool display this DTC as active?

      Yes 

      • Go To  2

      No 

      • Test complete, 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.
      • Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  2. MEASURE VOLTAGE AT THE DLC 
    Fig 1: Measuring Voltage Between Ground & CAN B Bus Circuits
    GC0154189Courtesy of CHRYSLER GROUP, LLC
    1. Disconnect the scan tool.
    2. Measure the voltage between ground and the CAN B Bus circuits.

      Does the voltage read approximately 4.65 - 4.98 volts on the (D42) CAN B Bus (-) and 0.39 - 0.46 volts on the (D41) CAN B (+) circuits?

      Yes 

      • Go To  3

      No - Voltage Between 0.3 - 0.7 Volt on Both Circuits 

      • Go To  9

      No - Voltage Reads 0 Volts on Either Circuit 

      • Go To  7

      No - Voltage Above 10 Volts on Either Circuit 

      • Go To  5
  3. CHECK THE (D41) CAN B BUS (+) CIRCUIT FOR AN OPEN 
    Fig 2: Checking CAN B Bus (+) Circuit For An Open
    GC0154190Courtesy of CHRYSLER GROUP, LLC
    1. Turn the ignition on.
    2. Reconnect the scan tool.
    3. With the scan tool, view the modules.
    4. Using a fused jumper wire, connect one end to ground and with the other end backprobe the (D41) CAN B Bus (+) circuit at the DLC harness connector.
      NOTE:

      This may cause some modules to no longer communicate on the Bus.

      Are some modules no longer communicating?

      Yes 

      • Using the Wiring Diagrams to further isolate the open in the circuit, repair the (D41) CAN B Bus (+) circuit for an open.
      • Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .

      No 

      • Go To  4
  4. CHECK THE (D42) CAN B BUS (-) CIRCUIT FOR AN OPEN 
    Fig 3: Checking CAN B Bus (-) Circuit For An Open
    GC0154191Courtesy of CHRYSLER GROUP, LLC
    1. Remove the fused jumper wire.
    2. Using a fused jumper wire, connect one end to ground and with the other end backprobe the (D42) CAN B Bus (-) circuit at the DLC harness connector.
      NOTE:

      This may cause some modules to no longer communicate on the Bus.

      Are some modules no longer communicating?

      Yes 

      • Using the Wiring Diagrams to further isolate the open in the circuit, repair the (D42) CAN B Bus (-) circuit for an open.
      • Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .

      No 

      • Inspect the wiring and connectors for damage. If OK, replace and program the module that set this DTC in accordance with the Service Information.
      • Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  5. CHECK THE (D41) CAN B BUS (+) CIRCUIT FOR A SHORT TO VOLTAGE 
    Fig 4: Measuring Voltage Between Ground & CAN B Bus Circuits
    GC0154189Courtesy of CHRYSLER GROUP, LLC
    1. Turn the ignition off.
    2. Disconnect the scan tool from the DLC.
    3. Turn the ignition on.
    4. Measure the voltage between the (D41) CAN B Bus (+) circuit and ground.

      Is the voltage above 10.0 volts?

      Yes 

      • Disconnect each CAN B Bus module one at a time while observing the voltage to determine if the short is caused by an internal short within a module. Replace the module, in accordance with the Service Information, that when disconnected eliminates the short to voltage. If the short condition is still present with all CAN B Bus modules disconnected use the Wiring Diagrams to help isolate and repair the (D41) CAN B Bus (+) circuit for a short to voltage.
      • Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .

      No 

      • Go To  6
  6. CHECK THE (D42) CAN B BUS (-) CIRCUIT FOR A SHORT TO VOLTAGE 
    Fig 5: Measuring Voltage Between Ground & CAN B Bus Circuits
    GC0154189Courtesy of CHRYSLER GROUP, LLC
    1. Measure the voltage between the (D42) CAN B Bus (-) circuit and ground.

      Is the voltage above 10.0 volts?

      Yes 

      • Disconnect each CAN B Bus module one at a time while observing the voltage to determine if the short is caused by an internal short within a module. Replace the module, in accordance with the Service Information, that when disconnected eliminates the short to voltage. If the short condition is still present with all CAN B Bus modules disconnected use the Wiring Diagrams to help isolate and repair the (D42) CAN B Bus (-) circuit for a short to voltage.
      • Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .

      No 

      • Inspect the wiring and connectors for damage. If OK, replace and program the module that set this DTC in accordance with the Service Information.
      • Perform the appropriate verification test for the module being replaced. If there is no verification test for the associated module Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  7. CHECK THE (D41) CAN B BUS (+) CIRCUIT FOR A SHORT TO GROUND 
    Fig 6: Checking CAN B Bus Circuit For A Short To Ground
    GC0154192Courtesy of CHRYSLER GROUP, LLC
    1. Turn the ignition off.
    2. Disconnect the scan tool from the DLC.
    3. Measure the resistance between ground and the (D41) CAN B Bus (+) circuit.

      Is the resistance above 1000.0 Ohms?

      Yes 

      • Go To  8

      No 

      • Disconnect each CAN B Bus module one at a time while observing the resistance to determine if the short is caused by an internal short within a module. Replace the module, in accordance with the Service Information, that when disconnected eliminates the short to ground. If the short condition is still present with all CAN B Bus modules disconnected use the Wiring Diagrams to help isolate and repair the (D41) CAN B Bus (+) circuit for a short to ground.
      • Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  8. CHECK THE (D42) CAN B BUS (-) CIRCUIT FOR A SHORT TO GROUND 
    Fig 7: Checking CAN B Bus Circuit For A Short To Ground
    GC0154192Courtesy of CHRYSLER GROUP, LLC
    1. Measure the resistance between ground and the (D42) CAN B Bus (-) circuit.

      Is the resistance above 1000.0 Ohms?

      Yes 

      • Inspect the wiring and connectors for damage. If OK, replace and program the module that set this DTC in accordance with the Service Information.
      • Perform the appropriate verification test for the module being replaced. If there is no verification test for the associated module Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .

      No 

      • Disconnect each CAN B Bus module one at a time while observing the resistance to determine if the short is caused by an internal short within a module. Replace the module, in accordance with the Service Information, that when disconnected eliminates the short to ground. If the short condition is still present with all CAN B Bus modules disconnected use the Wiring Diagrams to help isolate and repair the (D42) CAN B Bus (-) circuit for a short to ground.
      • Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  9. CHECK THE (D41) CAN B BUS (+) CIRCUIT FOR A SHORT TO THE (D42) CAN B BUS (-) CIRCUIT 
    Fig 8: Checking CAN B Bus (+) Circuit For A Short To CAN B Bus (-) Circuit
    GC0154193Courtesy of CHRYSLER GROUP, LLC
    1. Turn the ignition off.
    2. Disconnect the scan tool from the DLC.
    3. Measure the resistance between the (D41) CAN B Bus (+) circuit and (D42) CAN B Bus (-) circuit.

      Is the resistance below 1000.0 Ohms?

      Yes 

      • Disconnect each CAN B Bus module one at a time while observing the resistance to determine if the short is caused by an internal short within a module. Replace the module, in accordance with the Service Information, that when disconnected eliminates the short between the two circuits. If the short condition is still present with all CAN B Bus modules disconnected use the Wiring Diagrams to help isolate and repair the (D41) CAN B Bus (+) circuit for a short to the (D42) CAN B Bus (-) circuit.
      • Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .

      No 

      • Inspect the wiring and connectors for damage. If OK, replace and program the module that set this DTC in accordance with the Service Information.
      • Perform the appropriate verification test for the module being replaced. If there is no verification test for the associated module Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
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