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Rear Heated Seat Malfunction



Rear Heated Seat Malfunction

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview)provides an overview of each diagnostic category.



Circuit/System Description

Battery positive voltage is supplied to the rear heated seat module through the ignition 3 voltage circuit and the REAR HTD SEATS Fuse that is located in the left rear fuse block. This voltage is used to power up the heated seat module and to supply power to the seat heater elements. This voltage supply allows the heated seat system to operate only with the ignition switch in the ON position. The rear heated seat module is grounded through the module ground circuit and G402.


Diagnostic Aids

When performing resistance measurements on the heated seat system, make sure the seats are cooled. If the seat heating elements are still warm, resistance readings may be affected.


Reference Information
Schematic Reference

Heated/Cooled Seat Schematics (Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Rear Heated Seats Description and Operation (Rear Heated Seats Description and Operation)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Control Module References (Programming and Relearning)for Scan Tool Information


Circuit System Verification

1. Ignition ON, observe the rear heated seat cushion and seat back elements while activating the related heated seat switch. The heated seat cushion and seat back should heat when the switch is activated for each rear seat.

• If the heated seat cushion and seat back are inoperative for both rear seats, refer to Rear Heated Seat Malfunction.
• If the heated seat cushion or seat back is inoperative for only one seat, refer to Rear Heated Seat Element Malfunction.

2. Observe the rear heated seat temperature indicators while activating each rear heated seat switch to the low, medium, and high settings. The heated seat indicators should illuminate as the switch is activated.

• If one or all of the heated seat indicators are inoperative, refer to Rear Heated Seat Switch Indicator Malfunction.




Circuit/System Testing


Rear Heated Seat Malfunction
1. Ignition OFF, disconnect the X2 harness connector at the rear heated seat module.
2. Ignition OFF, test for less than 5 ohms between the ground circuit terminal A and ground.

• If greater than the specified range, test the ground circuit for an open/high resistance.

3. Ignition ON, test for B+ between the ignition 3 B+ circuit terminal C and ground.

• If not the specified value, test the B+ circuit for a short to ground or an open/high resistance.

4. Ignition OFF, connect the X2 harness connector at rear heated seat module.
5. Disconnect the harness connector at the rear HVAC control module.
6. Ignition ON, test for B+ between the rear heated seat switch B+ circuit terminal A5 and ground.

• If not the specified value, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the rear heated seat module.

7. Ignition OFF, connect the harness connector rear HVAC control module.
8. Disconnect the X3 harness connector at the rear heated seat module.
9. Connect a test lamp between the signal circuit terminal 4 and ground.
10. Ignition ON, observe the test lamp while pressing the right rear heated seat switch. The test lamp should illuminate ON and OFF as the switch is activated.

• If the test lamp does not illuminate, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the rear HVAC control module.
• If the test lamp is always ON, test the signal circuit for a short to voltage. If the circuit tests normal, replace the rear HVAC control module.

11. Connect a test lamp between the signal circuit terminal 5 and ground.
12. Ignition ON, observe the test lamp while pressing the left rear heated seat switch. The test lamp should illuminate ON and OFF as the switch is activated.

• If the test lamp does not illuminate, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the rear HVAC control module.
• If the test lamp is always ON, test the signal circuit for a short to voltage. If the circuit tests normal, replace the rear HVAC control module.

13. If all circuits test normal, replace the rear heated seat module.



Rear Heated Seat Element Malfunction
1. Ignition OFF, disconnect the X3 harness connector at the rear heated seat module.
2. Connect a test lamp between the inoperative rear heated seat switch signal circuit terminal and ground.
3. Ignition ON, observe the test lamp while pressing the appropriate heated seat switch. The test lamp should illuminate ON and OFF as the switch is activated.

• If the test lamp does not illuminate, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the rear HVAC control module.
• If the test lamp is always ON, test the signal circuit for a short to voltage. If the circuit tests normal, replace the rear HVAC control module.

4. Ignition OFF, connect the X3 harness connector at the rear heated seat module.
5. Disconnect the harness connector at the inoperative cushion heated seat element.
6. Ignition OFF, test for less than 10 ohms between the cushion heater element terminal A and terminal B at the cushion element.

• If greater than the specified range, replace the appropriate cushion heated seat element.

7. Test for 850-11.50K ohms between the inoperative cushion temperature sensor terminal C and terminal D.

• If not within the specified range, replace the appropriate cushion heated seat element.

8. Disconnect the harness connector at the inoperative back heated seat element.
9. Test for less than 10 ohms between the seat back heater element terminal A and terminal B at the seat back element.

• If greater than the specified range, replace the appropriate seat back heated seat element.

10. Ignition ON, test for 4.8-5.2 volts between the appropriate temperature sensor signal circuit terminal C and ground.

• If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the heated seat module.
• If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the heated seat module.

11. Ignition ON, test for 4.8-5.2 volts between the signal circuit terminal C and the low reference circuit terminal D.

• If less than the specified range, test the low reference circuit for a short the voltage or an open/high resistance. If the circuit tests normal, replace the heated seat module.

12. Ignition ON, verify that a test lamp illuminates between the cushion heater element B+ circuit terminal A and ground.

• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the rear heated seat module.

13. Ignition OFF, connect a test lamp between the appropriate cushion heater element B+ circuit terminal A and the cushion element control circuit terminal B.
14. Ignition ON, activate the appropriate rear heated seat switch ON and OFF. The test lamp should turn ON and OFF as the switch is activated.

• If the test lamp does not illuminate, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the rear heated seat module.
• If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the rear heated seat module.

15. Ignition OFF, connect a test lamp between the appropriate heated seat back heater element B+ circuit terminal A and the seat back element control circuit terminal B.
16. Ignition ON, activate the appropriate rear heated seat switch ON and OFF. The test lamp should turn ON and OFF as the switch is activated.

• If the test lamp does not illuminate, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the rear heated seat module.
• If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the rear heated seat module.

17. If all circuits test normal, replace the rear heated seat module.



Rear Heated Seat Switch Indicator Malfunction
1. Ignition OFF, disconnect the X3 harness connector at the rear heated seat module.
2. Ignition ON, verify the heated seat temperature indicators are OFF.

• If any of the indicators is ON, test the appropriate indicator control circuit for a short to ground. If the circuit tests normal, replace the rear HVAC control module.

3. Ignition ON, connect a test lamp between the inoperative heated seat temperature indicator control circuit and ground. The heated seat temperature indicator should illuminate.

• If the indicator does not illuminate, test the indicator control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the rear HVAC control module.

4. If all circuits test normal, replace the rear heated seat module.



Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Rear Seat Cushion Cover and Pad Replacement (Rear Seat Cushion Cover and Pad Replacement)
* Rear Seat Back Cushion Cover and Pad Replacement (Rear Seat Back Cushion Cover and Pad Replacement)
* Auxiliary Heater and Air Conditioning Control Replacement (Service and Repair)
* Control Module References (Programming and Relearning)for Rear Heated Seat Module replacement, setup, and programming


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