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Diagnostic Test

WARNING: This page is about a different car, the 2018 Jeep Grand Cherokee. However, it is still accessible from the selected car via links, so may be relevant.
  1. CHECK FOR AN ACTIVE DTC 
    1. With the scan tool, read DTCs and record on the repair order.
    2. Record the Environmental Data.
    3. With the scan tool, erase DTCs.
    4. Using the recorded Environmental Data, along with the When Monitored and Set Conditions above, operate the vehicle in the conditions that set the DTC.
    5. With the scan tool, read Drivetrain Control Module (DTCM) DTCs.

      Did the DTC return?

      Yes 

      • Go To  2

      No 

      • Perform the TESTING FOR AN INTERMITTENT CONDITION procedure. Refer to TESTING FOR AN INTERMITTENT CONDITION . Ask the costumer what the driving conditions were when the DTC set. Driving in adverse conditions could cause this DTC to set (e.g. mud, snow, sand, abusive driving, or testing on a 2WD dynomometer).
  2. CHECK FOR OTHER DTCS 
    1. Using the recorded information, check for Controller Area Network (CAN) related DTCs and Body Control Module (BCM) Ambient Temperature sensor DTCs.

      Are any of the specified DTCs set?

      Yes 

      • Repair the other DTCs before continuing with this procedure.

      No 

      • Go To  3
  3. CHECK THE TRANSFER CASE FLUID LEVEL AND CONDITION 
    1. Check the transfer Case fluid level and condition in accordance with the Service Information. Refer to appropriate service information.

      Is the fluid in good condition and at the proper level?

      Yes 

      • Go To  4

      No 

      • Repair the Transfer Case fluid condition in accordance with the Service Information. Refer to appropriate service information.
      • Perform the DTCM VERIFICATION TEST. Refer to DTCM VERIFICATION TEST .
  4. CHECK THE (T315) SHIFT MOTOR CONTROL A 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. CHECK THE (T316) 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 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 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  6

      No 

      • Repair the circuit for an open or high resistance.
      • Perform the DTCM VERIFICATION TEST. Refer to DTCM VERIFICATION TEST .
  6. CHECK RELATED HARNESS CONNECTIONS 
    1. Disconnect all 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 

      • Go To  7

      No 

      • The wiring or poor connection problem has been repaired.
      • Perform the DTCM VERIFICATION TEST. Refer to DTCM VERIFICATION TEST .
  7. REPLACE THE TRANSFER CASE SHIFT MOTOR AND CHECK FOR THE DTC TO RETURN 
    1. Replace the Transfer Case Shift Motor in accordance with the Service Information. Refer to MOTOR, SHIFT, REMOVAL .
    2. Connect the Transfer Case Shift Motor related electrical connectors and DTCM 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  8

      No 

      • Replacing the Transfer Case Shift Motor corrected the condition.
      • Perform the DTCM VERIFICATION TEST. Refer to DTCM VERIFICATION TEST .
  8. CHECK THE TRANSFER CASE CLUTCH FOR EXCESSIVE WEAR AND DAMAGE 
    1. Disassemble the Transfer Case in accordance with the Service Information and inspect the Clutch for excessive wear and damage. Refer to appropriate service information.

      Is the Transfer Case Clutch in good condition?

      Yes 

      No 

      • Replace the Transfer Case Clutch in accordance with the Service information. Refer to appropriate service information.
      • Perform the DTCM VERIFICATION TEST. Refer to DTCM VERIFICATION TEST .
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