Battery positive voltage is supplied to the rear heated seat module (RHSM) 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 RHSM is grounded through the module ground circuit and G402.

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.

Schematic Reference

Heated/Cooled Seat Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Rear Heated Seats Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Important: For valid verification information, the ignition must be cycled ON and OFF between the operation of each rear heated seat.

1. Ignition ON, turn ON the left and right rear heated seats as stated above. The seat cushion and seat back should get warm for each rear heated seat.

⇒	If the seat cushion and seat back are inoperative for both rear seats, refer to Both Rear Heated Seats Inoperative.

⇒	If just one of the rear heated seats is inoperative or always ON, refer to Rear Heated Seat Malfunction.

⇒	If just a seat back is inoperative, refer to Seat Back Heater Element Inoperative.

2. Observe the rear heated seat switch temperature indicators while pressing the appropriate rear heated seat switch through the high, medium, and low positions. The appropriate indicators should illuminate as the switch is activated.

⇒	If the heated seat operates normal, but one or all of the switch temperature indicators are inoperative or always ON, refer to Rear Heated Seat Switch Indicator Malfunction.

Both Rear Heated Seat Inoperative

1. Ignition OFF, disconnect the X2 harness connector at the RHSM.
2. 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, verify that a test lamp illuminates between the ignition circuit terminal C and ground.

⇒	If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.

4. Ignition OFF, connect the X2 harness connector at RHSM and disconnect the harness connector at the rear HVAC control module.
5. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal A5 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 RHSM.

6. Ignition OFF disconnect the X1 harness connector at the RHSM.
7. Test for 2.5-5.0 ohms between the control circuits listed below:

•	Left rear seat heater elements terminal 5 and terminal 11

•	Right rear seat heater elements terminal 6 and terminal 12

⇒	If greater than the specified range, test the appropriate control circuits for an open/high resistance.

⇒	If less than the specified range, test for a short between appropriate control circuits. If the circuits test normal, test or replace the appropriate seat cushion or seat back heater element.

8. Test for infinite resistance between the control circuits listed below and ground:

•	Left rear seat heater element terminal 5

•	Right rear seat heater element terminal 6

⇒	If not the specified value, test the appropriate control circuit for a short to ground.

9. Ignition ON, test for than 1.0 volt between the control circuits listed below and ground:

•	Left rear seat heater element terminal 5

•	Right rear seat heater element terminal 6

⇒	If greater than the specified value, test the appropriate control circuit for a short to voltage.

10. If all circuits test normal, replace the RHSM.

Rear Heated Seat Malfunction

1. Ignition OFF, disconnect the X3 harness connector at the RHSM.
2. Connect a test lamp between the appropriate signal circuit listed below and ground.

•	Left rear heated seat switch terminal 5

•	Right rear heated seat switch terminal 4

3. Ignition ON, press and release the appropriate rear heated seat switch. The test lamp should turn ON and OFF as the switch is pressed and released.

⇒	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.

⇒	If the test lamp is always OFF, 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.

4. Ignition OFF, connect the X3 harness connector at the RHSM and disconnect the X1 harness connector at the RHSM.
5. Test for 1000-15K ohms between the appropriate signal and low reference circuits listed below:

•	Left rear seat temperature sensor terminal 4 and terminal 1

•	Right rear seat temperature sensor terminal 9 and terminal 2

⇒	If greater than the specified range, test the signal and low reference circuits for a short to voltage or an open/high resistance. If the circuits test normal, test or replace the seat cushion heater element/temperature sensor.

⇒	If less than the specified range, test for a short between the signal and low reference circuits. If the circuits test normal, test or replace the seat cushion heater element/temperature sensor.

6. Connect the X1 harness connector at the RHSM and disconnect the harness connector at the appropriate seat cushion heater element.
7. At the heater element side of the connector, test for 6.0-13 ohms between terminal A and terminal B.

⇒	If not within the specified range, replace the seat cushion heater element.

8. At the RHSM side of the connector, connect a test lamp between the control circuit terminal A and ground.
9. Ignition ON, press the appropriate heated seat switch through the high, medium, and low positions to OFF. The test lamp should illuminate until the OFF position is reached or the module shuts down.

⇒	If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuits test normal, replace the RHSM.

⇒	If the test lamp is always ON, test the control circuit for a short to voltage. If the circuits test normal, replace the RHSM.

⇒	If the test lamp does not illuminate, test the control circuit terminal B for a short to voltage or an open/high resistance. If the circuits test normal, replace the RHSM.

10. At the RHSM side of the connector, connect a test lamp between control circuit terminal A and control circuit terminal B.
11. Press the appropriate heated seat switch through the high, medium, and low positions to OFF. The test lamp should illuminate until the OFF position is reached or the module shuts down.
12. Ignition ON, at the RHSM side of the connector, test for 4.8-5.2 volts between the 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 RHSM.

⇒	If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuits test normal, replace the RHSM.

13. If all circuits test normal, replace the RHSM.

Seat Back Heater Element Inoperative

1. Ignition OFF, disconnect the harness connector at the appropriate seat back heater element.
2. At the heater element side of the connector, test for 3.5-8.0 ohms between terminal A and terminal B.

⇒	If greater than the specified range, replace the seat back heater element.

3. At the RHSM side of the connector, connect a test lamp between control circuit terminal A and control circuit terminal B.
4. Ignition ON, press the appropriate heated seat switch through the high, medium, low positions to OFF. The test lamp should illuminate until the OFF position is reached.

⇒	If the test lamp does not illuminate, test the control circuits for an open/high resistance.

Rear Heated Seat Switch Indicator Malfunction

1. Ignition OFF, disconnect the X3 harness connector at the RHSM.
2. Ignition ON, verify the heated seat temperature indicators are OFF.

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

•	Left rear seat high temperature indicator terminal 9

•	Left rear seat medium temperature indicator terminal 3

•	Left rear seat low temperature indicator terminal 10

•	Right rear seat high temperature indicator terminal 8

•	Right rear seat medium temperature indicator terminal 7

•	Right rear seat low temperature indicator terminal 6

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

•	Left rear seat high temperature indicator terminal 9

•	Left rear seat medium temperature indicator terminal 3

•	Left rear seat low temperature indicator terminal 10

•	Right rear seat high temperature indicator terminal 8

•	Right rear seat medium temperature indicator terminal 7

•	Right rear seat low temperature indicator terminal 6

⇒	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 RHSM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.