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Home >> Jeep >> 2023 >> Wagoneer Carbide, RWD >> Repair and Diagnosis >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> Heating And Air Conditioning (ATC) - DTCS U0140-00 To U1519-00 >> DTC Troubleshooting >> U0247-00-Lost Communication With Comfort Seat And Wheel Module 1 >> Diagnostic Test

Diagnostic Test

  1. TESTING LIN BUS USING THE MOPAR SCOPE 
    NOTE:

    Some vehicles can have multiple LIN connections within a connector, make sure that you are testing the correct LIN circuit.

    For a complete LIN BUS SYSTEM wiring diagram, refer to the appropriate wiring information  .

    1. Connect the black pin for each test lead to Chassis ground. Connect the blue lead to the LIN circuit to be tested.
      GC0199043Courtesy of CHRYSLER GROUP, LLC
    2. Start the Mopar Scope.
    3. Turn the ignition on.
    4. Operate the systems connected to the LIN bus being tested to observe signal changes. Move connectors and wiring to look for any signal drop-out.
    5. When connected to the vehicle harness correctly, the LED on the breakout box will light up to indicate that there is activity on the bus.
    6. A waveform should appear.

      The image below is of a normal LIN bus waveform using the Mopar Scope.

      DESCRIPTION MEASUREMENT
      CHANNEL A 20 volts
      TIME BASE 1 ms/div [milliseconds / division control]
      ZOOM / VIEW X1 - HORIZONTAL & VERTICAL
      NOTE:

      The Mopar Scope has preset Guided Tests for Communications testing of the LIN bus.

      GC0199018Courtesy of CHRYSLER GROUP, LLC
    7. The waveform should reveal that data is being exchanged continuously along the LIN bus and the peak voltages are correct.
    8. Determine the type of LIN waveform fault (short, open, etc.) the vehicle presently has.

      Did the Mopar Scope show the LIN bus waveform fault?

      • Use the wiring diagrams as a guide to follow the path of the circuit(s) to isolate the fault further. Go To  2
      • The condition that originally caused the concern may not be present at this time.
      • Continue to use the Mopar Scope and wiring diagrams as a guide to trace the circuits and look for any in-line connectors where the fault could occur intermittently by wiggling the wire harness and connectors.
      • Look for any chafed, pierced, pinched, or partially broken wires.
      • Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the related wire harness connectors.
      • Perform any Technical Service Bulletins (TSBs) that may apply.
  2. READ AND RECORD DTCS AND ENVIRONMENTAL DATA - ERASE DTCS AND CHECK FOR DTC TO RETURN 
    1. With the scan tool, read DTCs in all Electronic Control Units (ECUs) and record on the repair order.
    2. With the scan tool, run a vehicle Scan Report, or record the Environmental Data related to the DTCs.
    3. With the scan tool, erase all DTCs.
    4. Turn the ignition off for a minimum of 10.0 seconds.
    5. Start the Engine.
    6. Turn the Left Front Heated Seat on.
    7. Using the recorded Environmental Data and the When Monitored Conditions, operate the vehicle in the conditions that set the DTC.
    8. With the scan tool, read Comfort Seat Module Left Front DTCs.

    Is the same DTC active?

    Yes 

    • Go To  3

    No 

  3. CHECK THE (F921) FUSED IGNITION CIRCUIT FOR AN OPEN (F62) 20A FUSE 

    Does the (F921) Fused Ignition Circuit have an open 20A fuse?

    Yes 

    No 

    • Go To  4
  4. ISOLATE AND LOAD TEST THE (F921) FUSED IGNITION CIRCUIT TO CHECK FOR AN OPEN OR HIGH RESISTANCE 
    1. The ignition must be off when performing a load test on a circuit.
    2. Isolate the circuit by disconnecting the Electronic Control Unit (ECU) and every component harness connector containing the circuit being tested.
    3. Connect the positive lead of the load test tool to the positive side of the Battery (A). Note:  Refer to the diagram below.
    4. Using an approved back probe tool, connect the negative lead of the load test tool to the circuit being tested at the one of the component harness connectors (B).
    5. Using an approved back probe tool and a fused jumper wire, connect the circuit being tested to the negative side of the Battery or a known good ground at the other component harness connector (C and D).
    6. The bulb on the load test tool should be illuminated and bright if there is no resistance in the circuit.
    NOTE:

    Note: Why load test a circuit?  A load test is used to determine if a circuit is capable of carrying the amperage needed to perform properly. The 3156 bulb in the load tool illustrated, is a simple but effective method of testing circuit functionality. A 3156 Bulb has approximately 6.0 Ohms of resistance when the bulb is powered  and draws approximately 2.0 amps of current. Read the CIRCUIT LOAD TESTING PROCEDURE for information on building a simple load test tool and for additional load testing information and alternative methods of load testing or voltage drop. Refer to CIRCUIT LOAD TESTING PROCEDURES .

    NOTE:

    Note:  A 12-volt test light can be substituted for the load test tool, but only  if the test light draws enough current to effectively load test the circuit. Many high impedance test lights draw very little amperage (less than 0.1 amps) and are not reliable to load test a circuit. To perform a proper load test of a circuit, the tool being used should draw more than approximately 0.75 amps.

    NOTE:

    Note: Why perform a Voltage Drop Test?  To verify with certainty there is not any resistance in the circuit being tested, perform a simple voltage drop test across the 3156 bulb of the load test tool. To do so perform the following:

    • 1. Connect the leads of a DVOM to the alligator clips on the load test tool while the load test tool is connected in series with the circuit.
    • 2. Compare the voltage drop across the bulb to the voltage reading across the Battery terminals.
    • 3. The voltage dropped across the bulb should be equal to the voltage reading across the Battery terminals if there is no resistance in the circuit being tested.

    Example:  2.0 Ohms of resistance in the circuit being tested will cause the voltage measurement across the bulb to be 25% less than when compared to Battery voltage. The reason for this is that the 2.0 Ohms in the circuit makes up 25% of the total circuit resistance of 8.0 Ohms. Read the CIRCUIT LOAD TESTING PROCEDURE for information on building a simple load test tool and for additional load testing information and alternative methods of load testing or voltage drop. Refer to CIRCUIT LOAD TESTING PROCEDURES .

    GC0174954Courtesy of CHRYSLER GROUP, LLC
    WARNING:

    To avoid possible serious or fatal injury, DO NOT load test any air bag/restraint system components or circuits using the procedures listed here. Refer to the Service Information for proper air bag/restraint system testing procedures.

    CAUTION:

    Do not load test any circuits with components still connected to the circuit.

    NOTE:

    When probing a circuit at an Electronic Control Unit (ECU) harness connector, always use an appropriate back probing tool to prevent any possible damage to the ECU terminals.

    NOTE:

    Compare the brightness of the bulb in the load test tool to that of a direct connection to Battery.

    Is the load test bulb illuminated and bright?

    Yes 

    • Go To  5

    No 

    • Repair the (Z921) Fused Ignition circuit for an open or high resistance.
    • Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  5. ISOLATE AND LOAD TEST THE (Z921) GROUND CIRCUIT TO CHECK FOR AN OPEN OR HIGH RESISTANCE 
    1. The ignition must be off when performing a load test on a circuit.
    2. Isolate the circuit by disconnecting the Electronic Control Unit (ECU) and every component harness connector containing the circuit being tested.
    3. Connect the positive lead of the load test tool to the positive side of the Battery (A). Note:  Refer to the diagram below.
    4. Using an approved back probe tool, connect the negative lead of the load test tool to the circuit being tested at the one of the component harness connectors (B).
    5. Using an approved back probe tool and a fused jumper wire, connect the circuit being tested to the negative side of the Battery or a known good ground at the other component harness connector (C and D).
    6. The bulb on the load test tool should be illuminated and bright if there is no resistance in the circuit.
    NOTE:

    Note: Why load test a circuit?  A load test is used to determine if a circuit is capable of carrying the amperage needed to perform properly. The 3156 bulb in the load tool illustrated, is a simple but effective method of testing circuit functionality. A 3156 Bulb has approximately 6.0 Ohms of resistance when the bulb is powered  and draws approximately 2.0 amps of current. Read the CIRCUIT LOAD TESTING PROCEDURE for information on building a simple load test tool and for additional load testing information and alternative methods of load testing or voltage drop. Refer to CIRCUIT LOAD TESTING PROCEDURES .

    NOTE:

    Note:  A 12-volt test light can be substituted for the load test tool, but only  if the test light draws enough current to effectively load test the circuit. Many high impedance test lights draw very little amperage (less than 0.1 amps) and are not reliable to load test a circuit. To perform a proper load test of a circuit, the tool being used should draw more than approximately 0.75 amps.

    NOTE:

    Note: Why perform a Voltage Drop Test?  To verify with certainty there is not any resistance in the circuit being tested, perform a simple voltage drop test across the 3156 bulb of the load test tool. To do so perform the following:

    • 1. Connect the leads of a DVOM to the alligator clips on the load test tool while the load test tool is connected in series with the circuit.
    • 2. Compare the voltage drop across the bulb to the voltage reading across the Battery terminals.
    • 3. The voltage dropped across the bulb should be equal to the voltage reading across the Battery terminals if there is no resistance in the circuit being tested.

    Example:  2.0 Ohms of resistance in the circuit being tested will cause the voltage measurement across the bulb to be 25% less than when compared to Battery voltage. The reason for this is that the 2.0 Ohms in the circuit makes up 25% of the total circuit resistance of 8.0 Ohms. Read the CIRCUIT LOAD TESTING PROCEDURE for information on building a simple load test tool and for additional load testing information and alternative methods of load testing or voltage drop. Refer to CIRCUIT LOAD TESTING PROCEDURES .

    GC0174954Courtesy of CHRYSLER GROUP, LLC
    WARNING:

    To avoid possible serious or fatal injury, DO NOT load test any air bag/restraint system components or circuits using the procedures listed here. Refer to the Service Information for proper air bag/restraint system testing procedures.

    CAUTION:

    Do not load test any circuits with components still connected to the circuit.

    NOTE:

    When probing a circuit at an Electronic Control Unit (ECU) harness connector, always use an appropriate back probing tool to prevent any possible damage to the ECU terminals.

    NOTE:

    Compare the brightness of the bulb in the load test tool to that of a direct connection to Battery.

    Is the load test bulb illuminated and bright?

    Yes 

    • Go To  6

    No 

    • Repair the (Z921) Fused Ignition circuit for an open or high resistance.
    • Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  6. CHECK FOR ACTIVE DTCS 
    1. With the scan tool, record and erase the DTCs.
    2. Cycle the ignition off, wait 10 seconds, then cycle the ignition on.
    3. With the scan tool, read the Active DTCs.

      Does the scan tool display; U0247-00-LOST COMMUNICATION WITH COMFORT SEAT AND WHEEL MODULE?

      Yes 

      • Go To  7

      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 poor pin fit.
      • Perform the BODY VERIFICATION TEST. Refer to DIAGNOSIS AND TESTING .
  7. REPLACE THE COMFORT SEAT MODULE LEFT FRONT AND RETEST FOR DTCS 
    1. Turn the ignition off.
    2. Replace the component in accordance with the Service Information. Refer to MODULE, COMFORT FRONT SEAT (CFSM), REMOVAL AND INSTALLATIONMODULE, COMFORT REAR SEAT (CRSM), REMOVAL AND INSTALLATIONMODULE, COMFORT STEERING WHEEL SURFACE (CSWSM), REMOVAL AND INSTALLATION .
    3. Connect the Comfort Seat Module Left Front harness connectors.
    4. Turn the ignition on.
    5. With the scan tool, erase all DTCs.
    6. Turn the ignition off for a minimum of 10.0 seconds.
    7. Turn the ignition on.
    8. Using the When Monitored and Set Conditions above and recorded data, operate the vehicle in the conditions that set the DTC.
    9. With the scan tool, read DTCs.

      Did the DTC return?

      Yes 

      • Go To  8

      No 

      • Replacing the faulty component repaired the fault.
      • Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  8. CHECK RELATED HARNESS CONNECTIONS 
    1. Disconnect all CSM 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.
      • Check for spread terminals and verify proper terminal tension.

      Repair any conditions that are found.

    5. Connect all CSM harness connectors. Be certain that all harness connectors are fully seated and the connector locks are fully engaged.
    6. Connect all in-line harness connectors (if equipped). Be certain that all connectors are fully seated and the connector locks are fully engaged.
    7. Connect 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. Test drive or operate the vehicle in accordance with the when monitored and set conditions.
    10. With the scan tool, read DTCs.

      Did the DTC return?

      Yes 

      No 

      • Test complete. The wiring or poor connection problem has been repaired.
      • Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
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