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Home >> Jeep >> 2024 >> Wagoneer Carbide, RWD >> Repair and Diagnosis >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> Heating And Air Conditioning (ATC) - DTCS B11FE-11 To B1E9A-11 >> DTC Troubleshooting >> B1E99-92-Front Left Heater Control 1-Performance Or Incorrect Operation >> Diagnostic Test

Diagnostic Test

  1. READ AND RECORD DTCS AND ENVIRONMENTAL DATA - ERASE DTCS AND CHECK FOR THE DTC TO RETURN 
      NOTE:

      This DTC will set if there is a fault on either the Seat Cushion or Seat Back temperature sensor circuits. This diagnostic procedure will cover checking both Heater Element Temperature Sensors and their related circuitry.

    2. With the scan tool, read Comfort Seat Module (CSM) DTCs and record on the repair order.
    3. For future reference, with the scan tool, run and save a vehicle Scan Report and all related recorded data.
    4. With the scan tool, erase all DTCs.
    5. Turn the ignition off for a minimum of 10.0 seconds.
    6. Turn the ignition on.
    7. Turn ON the Heated Seat.
    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 Next Step.

      No 

  2. CHECK RELATED HARNESS CONNECTIONS 
    1. Inspect related wiring harness and connectors between the Comfort Seat Module (CSM) and the Seat Cushion and Seat Back Heater for the following conditions:
      • Wiring insulation that has been torn, ripped or rubbed through on seat frame or other metal components that could cause a short to ground condition.
      • Corrosion.
      • Other signs of water intrusion.
      • Weather seal damage (if equipped).
      • Overheating due to a poor connection (terminal may be discolored due to excessive current draw).

      Were any of these conditions found?

      Yes 

      • Repair as necessary.

      No 

      • Go To Next Step.
  3. CHECK THE SENSOR SIGNAL CIRCUIT VOLTAGE 
    1. Turn the ignition off.
    2. Disconnect the Seat Cushion and Seat Back Heater harness connectors.
    3. Turn the ignition on.
    4. Measure the voltage of the Temperature Sensor Signal circuit at both the Seat Cushion and Seat Back Heater harness connectors.

      Is the voltage between 4.7 and 5.2 volts for both measurements?

      Yes 

      • Go To  7

      No 

      • Go To Next Step.
  4. ISOLATE AND CHECK THE TEMP SENSOR 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 ECU and component harness connectors containing the circuit being tested. Note:  Use the wiring diagram as a guide to follow the path of the circuit.
    3. Disconnect the Seat Cushion and Seat Back harness connectors.
    4. Disconnect the related CSM harness connector.
    5. Measure the resistance of the Temperature Sensor Signal circuit between the CSM and the Seat Cushion Heater harness connector.
    6. Measure the resistance of the Temperature Sensor Signal circuit between the CSM and the Seat Back Heater harness connector.

      Is the resistance below 3.0 Ohms for both measurements?

      Yes 

      • Go To Next Step.

      No 

      • Repair the circuit for an open or high resistance.
  5. ISOLATE AND CHECK THE TEMP SENSOR SIGNAL CIRCUIT FOR A SHORT TO GROUND 
    1. Turn the ignition off.
    2. Isolate the circuit by disconnecting the ECU and component harness connectors containing the circuit being tested. Note:  Use the wiring diagram as a guide to follow the path of the circuit.
    3. Before measuring the resistance of any circuit, first measure the resistance between the two leads of the DVOM. Note:  The meter leads can add resistance to the measurement value.
    4. Measure the resistance between ground and the Temperature Sensor Signal circuit at the Seat Cushion Heater harness connector.
    5. Measure the resistance between ground and the Temperature Sensor Signal circuit at the Seat Back Heater harness connector.
      NOTE:

      With the circuit isolated there should be no continuity between the circuit being tested and ground.

      Is there continuity between the circuit(s) being tested and ground?

      Yes 

      • Repair the circuit for a short to ground.

      No 

      • Go To Next Step.
  6. ISOLATE AND CHECK THE TEMP SENSOR SIGNAL CIRCUIT FOR A SHORT TO ANOTHER CIRCUIT AT THE CSM HARNESS CONNECTOR 
    1. The ignition must be off when performing a resistance check to find a short between circuits.
    2. Isolate the circuit by disconnecting the ECU and every component harness connector containing the circuit being tested. At this time leave all in-line connectors connected. Note:  Use the wiring diagram as a guide to follow the path of the circuit.
    3. Connect one lead of the DVOM to the Seat Cushion Temperature Sensor Signal circuit at the ECU harness connector.
    4. With the other lead of the DVOM probe all other circuits at the ECU harness connector.
    5. Connect one lead of the DVOM to the Seat Back Temperature Sensor Signal circuit at the ECU harness connector.
    6. With the other lead of the DVOM probe all other circuits at the ECU harness connector.
      NOTE:

      With the circuit isolated there should be no continuity between the circuit being tested and any other circuit.

      Is there continuity between the either of the Temperature Sensor Signal circuits and any other circuit?

      Yes 

      • Repair the short between the circuits that have continuity. Use the wiring diagram as a guide to trace the circuits and look for any in-line connectors to help isolate the location of the short.

      No 

      • Go To  11
  7. ISOLATE AND CHECK THE TEMP SENSOR GROUND CIRCUIT FOR AN OPEN/HIGH RESISTANCE 
    1. The ignition must be off when checking the continuity of a circuit.
    2. Before measuring the resistance of any circuit, first measure the resistance between the two leads of the DVOM. Note:  The meter leads can add resistance to the measurement value.
    3. Disconnect the Seat Cushion and Seat Back Heater harness connectors.
    4. Disconnect the related CSM harness connector.
    5. Measure the resistance of the Sensor Ground circuit between the CSM and the Seat Cushion Heater harness connector.
    6. Measure the resistance of the Sensor Ground circuit between the CSM and the Seat Back Heater harness connector.

      Is the resistance below 3.0 Ohms for both measurements ?

      Yes 

      • Go To Next Step.

      No 

      • Repair the circuit for an open or high resistance.
  8. ISOLATE AND CHECK THE TEMP SENSOR GROUND CIRCUIT FOR A SHORT TO ANOTHER CIRCUIT AT THE CSM HARNESS CONNECTOR 
    1. The ignition must be off when performing a resistance check to find a short between circuits.
    2. Isolate the circuit by disconnecting the ECU and every component harness connector containing the circuit being tested. At this time leave all in-line connectors connected. Note:  Use the wiring diagram as a guide to follow the path of the circuit.
    3. Connect one lead of the DVOM to the circuit being tested at the ECU harness connector.
    4. With the other lead of the DVOM probe all other circuits at the ECU harness connector.
      NOTE:

      With the circuit isolated there should be no continuity between the circuit being tested and any other circuit.

      Is there continuity between the circuit being tested and any other circuit?

      Yes 

      • Repair the short between the circuits that have continuity. Use the wiring diagram as a guide to trace the circuits and look for any in-line connectors to help isolate the location of the short.

      No 

      • Go To Next Step.
  9. CHECK THE SEAT CUSHION TEMP SENSOR RESISTANCE 
    1. Turn the ignition off.
    2. Disconnect the Seat Cushion Heater harness connector
    3. Measure the resistance of the Seat Cushion Temp Sensor by connecting an ohmmeter between terminals 2 and 3 of the Seat Cushion Heater harness connector (component side).
      4. NOTE:

      The Temp Sensor resistance should be between 9K ohms (at 80*F) and 16K ohms (at 60*F)

    4. Is the resistance between 9, 000 and 16, 000 ohms?

      Yes 

      • Go To Next Step.

      No 

      • Replace the Seat Cushion Heater in accordance with the Service Information.
  10. CHECK THE SEAT BACK TEMP SENSOR RESISTANCE 
    1. Turn the ignition off.
    2. Disconnect the Seat Back Heater harness connector
    3. Measure the resistance of the Seat Back Temp Sensor by connecting an ohmmeter between terminals 2 and 3 of the Seat Back Heater harness connector (component side).
      4. NOTE:

      The Temp Sensor resistance should be between 9K ohms (at 80*F) and 16K ohms (at 60*F)

    4. Is the resistance between 9, 000 and 16, 000 ohms?

      Yes 

      • Go To Next Step.

      No 

      • Replace the Seat Back Heater in accordance with the Service Information.
  11. CHECK RELATED HARNESS CONNECTIONS 
    1. Disconnect all ECU 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 ECU 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. Turn the ignition on.
    9. With the scan tool, erase DTCs.
    10. Turn ON the Heated Seat.
    11. Test drive or operate the vehicle in accordance with the when monitored and set conditions.
    12. With the scan tool, read DTCs.

      Did the DTC return?

      Yes 

      • Replace the Comfort Seat Module in accordance with the Service Information.
      • Perform the HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .

      No 

      • Test complete. The wiring or poor connection problem has been repaired.
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