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Home >> Jeep >> 2021 >> Gladiator Mojave, Part Time T/Case Control, Automatic Trans >> Repair and Diagnosis >> Transmission >> Transfer Case >> Drivetrain Control Module (DTCM) - DTCS C1477-4B To U0429-00 >> DTC Troubleshooting >> C147B-14-Front Axle Disconnect Sensor-Circuit Short To Ground Or Open >> Diagnostic Test

Diagnostic Test

  1. READ AND RECORD DTCS AND ENVIRONMENTAL DATA - ERASE DTCS AND CHECK FOR THE 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.
    3. With the scan tool, erase DTCs.
    4. Turn the ignition off for at least 10.0 seconds.
    5. Turn the ignition on.
    6. Using the recorded Environmental Data and the When Monitored Conditions, operate the vehicle in the conditions that set the DTC.
    7. With the scan tool, read DTCs.

    Did the DTC return?

    Yes 

    • Go To  2

    No 

  2. REVIEW FAD SCAN TOOL DATA 
    1. The ignition must be on, with engine off when performing this test.
    2. Place vehicle in park and 2wd selection.
    3. Under the DTCM listing, ocate the FAD actuator status under the data tab.
    NOTE:

    Under the conditions listed above the FAD status should show disengaged.

    Dose the scan tool show a disengaged status?

    Yes 

    • Go To 3

    No 

    • Go To  4
  3. FRONT AXLE DISCONNECT ACTUATOR TEST 
    1. The ignition must be on when performing this test.
    2. Raise the vehicle on a frame lift.
    3. Locate the FAD actuator wiring connector.
    4. Back probe the (G304) Circuit at the FAD connector, using a suitable back probing tool connected to a good ground source.
    NOTE:

    You should hear the FAD motor actuate engaging the FAD.

    Did you hear the FAD Actuate ?

    Yes 

    • Go To  4

    No 

    • Go To 6
  4. ISOLATE AND CHECK THE (G303) FRONT AXLE LOCK SIGNAL CIRCUIT FOR AN OPEN/HIGH RESISTANCE 
    1. The ignition must be off when checking the continuity of a circuit.
    2. Isolate the circuit by disconnecting the Electronic Control Unit (ECU) and the component harness connectors containing the circuit being tested. Note:  Use the wiring diagram as a guide to follow the path of the circuit. Check the disconnected connectors and related harnesses for damage, corrosion, and loose fitting terminals.
    3. Before testing a circuit, measure the resistance between the two leads of the Digital Volt-Ohm Meter (DVOM). Note:  Resistance in the meter leads can cause an error in the test results.
    4. Connect one lead of the DVOM to the circuit being tested at the component harness connector.
    5. Connect the other lead to the circuit being tested at the ECU harness connector and measure the resistance of the circuit.
    NOTE:

    When back-probing a circuit at a harness connector, always use an appropriate back probing tool to prevent damage to the connector terminals.

    Is the resistance below 3.0 Ohms?

    Yes 

    • Go To  5

    No 

    • Repair the circuit for an open or high resistance.
    • Perform the DTCM VERIFICATION TEST. Refer to DTCM VERIFICATION TEST .
  5. ISOLATE AND CHECK THE (G303) FRONT AXLE LOCK SIGNAL CIRCUIT FOR A SHORT TO GROUND 
    1. The ignition must be off when checking a circuit for continuity to ground.
    2. Isolate the circuit by disconnecting the ECU and the component harness connectors containing the circuit being tested. Note:  Use the wiring diagram as a guide to follow the path of the circuit. Check the disconnected connectors and related harnesses for damage, corrosion, and loose fitting terminals.
    3. Connect the negative lead of the DVOM to a known good ground.
    4. With the positive lead of the DVOM, probe the circuit being tested at the component harness connector and check for continuity between the circuit and ground.
    NOTE:

    When back-probing a circuit at a harness connector, always use an appropriate back probing tool to prevent damage to the connector terminals.

    Is there continuity between ground and the circuit being tested?

    Yes 

    • Repair the circuit for a short to ground. Use the wiring diagram as a guide to trace the circuit and identify any in-line connectors that may help isolate the location of the short.
    • Perform the DTCM VERIFICATION TEST. Refer to DTCM VERIFICATION TEST .

    No 

    • Go To  6
  6. CHECK THE (F946) FUSED IGNITION RUN/START CONTROL OUTPUT CIRCUIT FOR AN OPEN OR HIGH RESISTANCE BY LOAD TESTING THE CIRCUIT 
    1. Disconnect the applicable ECU harness connector.
    2. Connect the positive lead of the load test tool to the 12.0 volt supply circuit at the ECU harness connector. Note:  refer to (A) in the diagram below.
    3. Connect the negative lead of the load test tool to the ground circuit of the Battery or a good chassis ground.
    4. Make sure that the circuit being tested is being powered on. If the 12.0 volt circuit being tested is an ignition feed for example, the ignition must be on. If testing an output from a relay, verify that the relay is energized and on.
    5. The bulb on the load test tool should be illuminated and bright if there is no resistance in the circuit ry.
    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 LOAD TESTING A BATTERY OR IGNITION FEED CIRCUIT procedure in CIRCUIT VOLTAGE DROP AND LOAD TESTING PROCEDURES for information on building a simple load test tool and for additional load testing information and alternative methods of load testing or voltage drop testing a circuit. Refer to STANDARD PROCEDURE .

    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:

    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 LOAD TESTING A BATTERY OR IGNITION FEED CIRCUIT for information on building a simple load test tool and for additional load testing information and alternative methods of load testing or voltage drop testing a circuit. Refer to STANDARD PROCEDURE .

    GC0174938Courtesy of CHRYSLER GROUP, LLC
    NOTE:

    When back-probing a circuit at a harness connector, always use an appropriate back probing tool to prevent damage to the connector 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  7

    No 

    • Check the applicable fuse. If the fuse is open, repair the short to ground in the (F946) Fused Ignition Run/Start Control Output circuit.
    • Perform the HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .
  7. CHECK THE (F525) FUSED IGNITION SWITCH OUTPUT (RUN) CIRCUIT FOR AN OPEN OR HIGH RESISTANCE BY LOAD TESTING THE CIRCUIT 
    1. Disconnect the Front Axle Disconnect (FAD) Actuator harness connector.
    2. Connect the positive lead of the load test tool to the 12.0 volt supply circuit at the FAD Actuator harness connector. Note:  refer to (A) in the diagram below.
    3. Connect the negative lead of the load test tool to the ground circuit of the Battery or a good chassis ground.
    4. Make sure that the circuit being tested is being powered on. If the 12.0 volt circuit being tested is an ignition feed for example, the ignition must be on. If testing an output from a relay, verify that the relay is energized and on.
    5. The bulb on the load test tool should be illuminated and bright if there is no resistance in the circuit ry.
    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 LOAD TESTING A BATTERY OR IGNITION FEED CIRCUIT procedure in CIRCUIT VOLTAGE DROP AND LOAD TESTING PROCEDURES for information on building a simple load test tool and for additional load testing information and alternative methods of load testing or voltage drop testing a circuit. Refer to STANDARD PROCEDURE .

    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:

    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 LOAD TESTING A BATTERY OR IGNITION FEED CIRCUIT for information on building a simple load test tool and for additional load testing information and alternative methods of load testing or voltage drop testing a circuit. Refer to STANDARD PROCEDURE .

    GC0174938Courtesy of CHRYSLER GROUP, LLC
    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  8

    No 

    • Repair the 12.0 volt circuit for an open or high resistance.
    • Perform the HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .
  8. REPLACE THE FAD ACTUATOR AND CHECK FOR THE DTC TO RETURN 
    1. Replace the FAD Actuator in accordance with the Service Information. .
    2. Connect the FAD and all other harness connectors.
    3. Turn the ignition on.
    4. With the scan tool, erase DTCs.
    5. Using the recorded Environmental Data and the When Monitored conditions, operate the vehicle in the conditions that set the DTC.
    6. With the scan tool, read DTCs.

    Did the DTC return?

    Yes 

    • Go To  9

    No 

    • Replacing the FAD corrected the condition.
    • Perform the DTCM VERIFICATION TEST. Refer to DTCM VERIFICATION TEST .
  9. CHECK RELATED HARNESS CONNECTIONS 
    1. Disconnect all Drivetrain Control Module (DTCM) 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.
      • Perform a terminal drag test on each connector terminal to verify proper terminal tension.

      Repair any conditions that are found.

    5. Reconnect all DTCM harness connectors. Be certain that all harness connectors are fully seated and the connector locks are fully engaged.
    6. Reconnect all in-line harness connectors (if equipped). Be certain that all connectors are fully seated and the connector locks are fully engaged.
    7. Reconnect 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. Using the recorded Environmental Data, along with the When Monitored and Set Conditions above, operate the vehicle in the conditions that set the DTC.
    10. With the scan tool, read DTCM DTCs.

      Did the DTC return?

      Yes 

      No 

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