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Home >> Fiat >> 2018 >> 124 Spider Classica, Standard Trans >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 2 ((Aw6R31 Automatic Transmission Control Module (TCM) - Electrical Diagnostics)) >> DTC Troubleshooting >> U0155-00-Lost Communication With Cluster-CCN >> Diagnostic Test

Diagnostic Test

WARNING: This page is about a different variant/trim than selected.
  1. CHECK FOR PRESENCE OF SHORT CIRCUIT TO BATTERY ON THE CAN H (HS-CAN) LINE 
    1. Measure the voltage between pin F of the diagnostic connector (CAN H line) and body.

      Is a voltage of 12 V measured?

      Yes 

      • Short circuit to battery has occurred on the CAN H line.
      • Move on to Step.  3.

      No 

      • Move on to Step.  2.
  2. CHECK FOR PRESENCE OF SHORT CIRCUIT TO GROUND ON THE CAN H (HS-CAN) LINE 
    1. Measure the voltage between pin E of the diagnostic connector (CAN L line) and ground.

      Is voltage higher than 0 V?

      Yes 

      • Short circuit to ground has occurred on the CAN L line.
      • Move on to Step.  7.

      No 

      • Move on to Step.  5.
  3. CHECK FOR PRESENCE OF SHORT CIRCUIT TO BATTERY ON THE HS-CAN LINE 
    1. pin F of the diagnostic connector (CAN H line) and body
    2. pin E of the diagnostic connector (CAN L line) and body

      Is a voltage of 12 V measured between any one of these pins?

      Yes 

      • Short circuit to battery has occurred on the HS-CAN line.
      • Move on to Step.  4.

      No 

      • Move on to Step. 5.
  4. CHECK FOR PRESENCE OF SHORT CIRCUIT TO BATTERY OF THE INSTRUMENT PANEL NODE 
    1. Go to key-off condition.
    2. Disconnect the negative battery lead.
    3. Disconnect the Instrument Panel Node connector.
    4. Connect the negative battery lead.
    5. Go to key-on condition (engine off).
    6. Measure voltage on pins F and E of the diagnostic connector.

      Is the measured voltage 1.5 - 3.5 V?

      Yes 

      • Replace the Instrument Panel Node because subject to short circuit to battery.
      • If the error occurs again, move on to Step.  9.

      No 

      • Repair or replace the wiring between Instrument Panel Node and the rest of the system because the wiring is subject to short circuit to battery.
  5. CHECK FOR PRESENCE OF OPEN CIRCUIT ON THE HS-CAN LINE 
    1. pin F of the diagnostic connector (CAN H line) and body
    2. pin E of the diagnostic connector (CAN L line) and body

      Is the voltage between the terminals the same?

      Yes 

      • Short circuit has occurred between the terminals of the HS-CAN line.
      • Move on to Step.  6.

      No 

      • Check the electric connections again.
      • Replace the Instrument Panel Node if the error occurs again.
  6. CHECK FOR PRESENCE OF FAULT ON THE HS-CAN LINE CIRCUIT 
    1. pin F of the diagnostic connector (CAN H line) and body
    2. pin E of the diagnostic connector (CAN L line) and body

      Does the voltage between the pins correspond to 0V?

      Yes 

      • Short circuit to ground has occurred on the CAN H (HS-CAN) line.
      • Move on to Step.  7.

      No 

      • A short circuit between the CAN H and the CAN L (HS-CAN) has occurred.
      • Move on to Step.  8.
  7. CHECK FOR PRESENCE OF SHORT CIRCUIT TO GROUND ON THE INSTRUMENT PANEL NODE CAN LINE 
    1. Disconnect the Instrument Panel Node connector.
    2. pin B of Instrument Panel Node (wiring side) and body
    3. pin D of Instrument Panel Node (wiring side) and body

      Is short-circuit present?

      Yes 

      • Repair or replace the wiring between Instrument Panel Node and the rest of the system because the wiring is subject to short circuit to ground.

      No 

      • Replace the Instrument Panel Node because subject to short circuit to ground.
      • If the error occurs again, move on to Step.  9.
  8. CHECK FOR PRESENCE OF SHORT CIRCUIT BETWEEN THE INSTRUMENT PANEL NODE TERMINALS 
    1. Go to key-off condition.
    2. Disconnect the negative battery lead.
    3. Disconnect the Instrument Panel Node connector.
    4. Check continuity between pin F and pin E of the diagnostic connector.

      Is short-circuit present?

      Yes 

      • Repair or replace the wiring between Instrument Panel Node and the rest of the system because the wiring is subject to short circuit to between the terminals.

      No 

      • Replace the Instrument Panel Node because subject to short circuit to between the terminals.
      • If the error occurs again, move on to Step.  9.
  9. CHECK THAT THE TRANSMISSION CONTROL MODULE IS WORKING PROPERLY 
    1. Carry out the Transmission Control Module error deletion procedure.
    2. Check whether the error is still present.

      Is the error still present?

      Yes 

      • Repeat the checks from Step  1
      • Replace the Transmission Control Module if the error occurs again.

      No 

      • End of diagnosis.
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