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Diagnostic Test

WARNING: This page is about a different car, the 2017 Jeep 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 HVAC Module DTCs.

      Did the DTC return?

      Yes 

      • Go To  2

      No 

  2. CHECK THE (L24) AUTO HEADLAMPS SIGNAL CIRCUIT FOR A SHORT TO VOLTAGE 
    1. Turn the ignition off.
    2. Disconnect the HVAC Module C1 harness connector.
    3. Turn the ignition on.
    4. Measure voltage on the (L24) Auto Headlamps Signal circuit.

      Is there any voltage present?

      Yes 

      • Repair the (L24) Auto Headlamps Signal circuit for a short to voltage.
      • Perform the HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .

      No 

      • Go To  3
  3. CHECK THE (L24) AUTO HEADLAMPS SIGNAL CIRCUIT FOR AN OPEN 
    1. Turn the ignition off.
    2. Disconnect the Sun Sensor harness connector.
    3. Measure the resistance of the (L24) Auto Headlamps Signal circuit between the HVAC Module C1 harness connector and the Sun Sensor harness connector.

      Is the resistance below 3.0 Ohms?

      Yes 

      • Go To  4

      No 

      • Repair the (L24) Auto Headlamps Signal circuit for an open.
      • Perform the HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .
  4. CHECK THE (G939) SENSOR GROUND CIRCUIT FOR AN OPEN 
    1. Measure the resistance of the (G939) Sensor Ground circuit between the HVAC Module C1 harness connector and the Sun Sensor harness connector.

      Is the resistance below 3.0 Ohms?

      Yes 

      • Go To  5

      No 

      • Repair the (G939) Sensor Ground circuit for an open.
      • Perform the HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .
  5. CHECK THE SUN SENSOR FOR PROPER OPERATION 
    1. Replace the Sun Sensor in accordance with the Service Information. Refer to SENSOR, SUN, REMOVAL .
    2. Perform the HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .

      Did the DTC return while performing the HVAC Verification Test?

      Yes 

      • Go To  6

      No 

      • Replacing the Sun Sensor corrected the condition.
  6. CHECK RELATED HARNESS CONNECTIONS 
    1. Disconnect all HVAC Module 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 HVAC Module 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 HVAC Module DTCs.

      Did the DTC return?

      Yes 

      No 

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