For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Heated Seat Module B+ | 1 | 1 | -- | --
Heated Seat Switch Ignition Voltage | 1 | 1 | -- | --
Heated Seat High/Low Signal | 1 | 1 | -- | --
Heated Seat Switch Signal | 1 | 1 | -- | --
Heated Seat Temperature Sensor Signal | 1 | 1 | 1 | --
Seat Heater Element Voltage Control | 1 | 1 | -- | --
Heated Seat Temperature Sensor Ground | -- | 1 | -- | --
Seat Heater Element Ground | -- | 1 | -- | --
Heated Seat Switch Indicator Ground | -- | 2 | -- | --
Heated Seat Module Ground | -- | 1 | -- | --
1. Heated seat inoperative 2. Heated seat indicators inoperative

### Circuit/System Description

Battery positive voltage is supplied at all times to the heated seat module through the battery positive voltage circuit and the TRUNK/HTD SEATS 20 A fuse located in the underhood fuse block. When commanded ON, the heated seat module uses this voltage to heat the seat heating elements. Ground for the heated seat module, the seat heater elements, and the seat temperature sensor is provided through the module ground circuit at G301 for the driver seat and G201 for the passenger seat.

When the heated seat switch is placed in either the high or low temperature position, battery positive voltage is applied through the heated seat switch signal circuit to the heated seat module. At the same time, battery voltage is also applied through one of two resistors in the switch signal circuit and the heated seat HI/LO signal circuit to the module. In response to these switch signals, the heated seat module applies battery positive voltage through the heated seat element control circuit to the seat heating elements. When the heated seat switch is in the HIGH heat position, battery voltage is applied through a 1.1 kΩ resistor and the module sets the seat temperature to high heat. When the heated seat switch is in the LOW heat position, battery voltage is applied through a 2.2 kΩ resistor and the module sets the seat temperature to low heat.

### Reference Information

#### Schematic Reference

Heated/Cooled Seat Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Heated Seats Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

### Circuit/System Verification

1. Ignition ON, place the heated seat switch in the high heat position. The seat cushion and seat back should get warm.

⇒ | If the heated seat is inoperative or always ON, refer to Heated Seats Malfunction.

2. Ignition ON, place the heated seat switch in the low heat position. The seat cushion and seat back should get warm.

⇒ | If the heated seat is inoperative, refer to the Heated Seat Switch component test. If the switch tests normal, replace the heated seat module.

3. Observe the heated seat switch temperature indicators while pressing the appropriate heated seat switch through the high and low heat positions. The appropriate indicators should illuminate when the switch is pressed.

⇒ | If either indicator does not illuminate or is always ON, refer to Heated Seat Switch Indicator Malfunction.

### Circuit/System Testing

#### Heated Seats Malfunction

1. Ignition OFF, disconnect the harness connector at the appropriate heated seat switch.
2. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal D and ground.

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

3. Ignition OFF, connect the harness connector at the heated seat switch and disconnect the harness connector at the heated seat module.
4. Test for less than 1 Ω between the ground circuit terminal 4 and ground.

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

5. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 5 and ground.

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

6. Connect a test lamp between the signal circuit terminal 8 and ground.
7. Toggle the heated seat HIGH heat switch ON and OFF. The test lamp should turn ON and OFF when changing between the commanded states.

⇒ | If the test lamp is always OFF, test the signal circuit for a short to ground or an open/high resistance. If the circuits test normal, test or replace the heated seat switch.

⇒ | If the test lamp is always ON, test the signal circuit for a short to voltage. If the circuits test normal, test or replace the heated seat switch.

8. Toggle the heated seat LOW heat switch ON and OFF. The test lamp should turn ON and OFF when changing between the commanded states.

⇒ | If the test lamp does not turn ON and OFF, test or replace the heated seat switch.

9. Verify that a test lamp does not illuminate between the signal circuit terminal 3 and ground with the heated seat switch in the OFF position.

⇒ | If the test lamp illuminates, test the signal circuit for a short to voltage. If the circuit tests normal, test or replace the heated seat switch.

10. Test for B+ between the signal circuit terminal 3 and ground with the heated seat switch in the HIGH heat position.

⇒ | If not the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the heated seat switch.

11. Test for B+ between the signal circuit terminal 3 and ground with the heated seat switch in the LOW heat position.

⇒ | If not the specified value, test or replace the heated seat switch.

12. Ignition OFF, disconnect the harness connector at the seat back heater element.
13. Test for less than 1 Ω between the ground circuit terminal B and ground.

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

14. At the heater element side of the connector, test for 1 - 5 Ω between terminal A and terminal B.

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

15. Connect the harness connector at the seat back heater element.
16. Ignition ON, verify that a test lamp does not illuminate between the terminals listed below and ground:

• | Temperature sensor signal circuit terminal 6

• | Heater element control circuit terminal 7

⇒ | If the test lamp illuminates, test the appropriate circuit for a short to voltage.

17. Test for 1 - 5 Ω between the control circuit terminal 7 and the ground circuit terminal 4.

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

18. Test for 2.5 k - 15 kΩ between the signal circuit terminal 6 and the ground circuit terminal 4.

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

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

#### Heated Seat Switch Indicator Malfunction

1. Ignition OFF, disconnect the harness connector at the appropriate heated seat switch.
2. Test for less than 1 Ω between the ground circuit terminal E and ground.

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

3. If all circuits test normal, replace the heated seat switch.

### Component Testing

#### Heated Seat Switch

1. Ignition OFF, disconnect the harness connector at the appropriate heated seat switch.
2. Test for infinite resistance between the B+ terminal D and the signal terminal A with the switch in the open position.

⇒ | If not the specified value, replace the heated seat switch.

3. Test for 1.98 k - 2.22 kΩ between the B+ terminal D and the signal terminal A with the switch in the low position.

⇒ | If not within the specified range, replace the heated seat switch.

4. Test for 990 Ω - 1.21 kΩ between the B+ terminal D and the signal terminal A with the switch in the high position.

⇒ | If not within the specified range, replace the heated seat switch.

5. Test for infinite resistance between the B+ terminal D and the signal terminal F with the switch in the open position.

⇒ | If not the specified value, replace the heated seat switch.

6. Test for less than 2 Ω between the B+ terminal D and the signal terminal F with the switch in the HIGH position.

⇒ | If greater than specified range, replace the heated seat switch.

7. Test for less than 2 Ω between the B+ terminal D and the signal terminal F with the switch in the LOW position.

⇒ | If greater than specified range, replace the heated seat switch.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Driver or Passenger Seat Heater Switch Replacement

• | Driver or Passenger Seat Back Cushion Heater Replacement

• | Driver or Passenger Seat Cushion Heater Replacement

• | Control Module References for the heated seat module replacement, setup, and programming