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 | -- | --
Lumbar Adjuster Switch B+ | 1 | 1 | -- | --
Heated Seat Switch Signal | 1 | 1 | 1 | --
Heated Seat Cushion Temperature Sensor Signal | 1 | 1 | 1 | --
Heated Seat Heater Element Control | 1 | 1 | 2 | --
Heated Seat Cushion Temperature Sensor Low Reference | -- | 1 | -- | --
Heated Seat Heater Element Ground | -- | 1 | -- | --
Heated Seat Module Ground | -- | 1 | -- | --
1. Heated seat inoperative 2. Heated seat always ON

### Circuit/System Description

Battery voltage is supplied at all times to the heated seat module from the HTD/SEATS 20A fuse located in the underhood fuse block. Ignition voltage is supplied to the lumbar adjuster switch through the PWR HTR SWITCH 10A fuse also located in the underhood fuse block. When the heated seat switch is in either the HI or LO heat position, ignition voltage is applied through one of the internal resistors of the switch and the switch signal circuit to the heated seat module. In response to this signal, the heated seat module applies battery voltage through the heater element control circuit to the seat cushion and seat back heater elements for heated seat operation.

### Diagnostic Aids

The heated seat switch is a component of the seat lumbar adjuster switch. In various places in the diagnostics the lumbar adjuster switch will be called out.

### 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

#### Driver Heated Seat

1. Ignition ON, operate the heated seat switch to the high and low heat positions. The heated seat should activate and the switch indicator should illuminate when the switch is in the high and low heat positions.

⇒ | If the heated seat switch indicator does not illuminate or is always illuminated, refer to the Driver Heated Seat Switch Circuit Test.

2. If the heated seat switch indicator operates normal, refer to the Heated Seat Circuit Test.

#### Passenger Heated Seat

1. Ignition ON, seat belt buckled, operate the heated seat switch to the high and low heat positions. The heated seat should activate and the switch indicator should illuminate when the switch is in the high and low heat positions.

⇒ | If the heated seat switch indicator does not illuminate or is always illuminated, refer to the Passenger Heated Seat Switch Circuit Test.

2. If the heated seat switch indicator operates normal, refer to the Heated Seat Circuit Test.

### Circuit/System Testing

#### Driver Heated Seat Switch Circuit Test

1. Ignition OFF, disconnect the harness connector at the driver seat lumbar adjuster switch.
2. Test for less than 5 Ω 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. If all circuits test normal, test or replace the driver seat lumbar adjuster switch.

#### Passenger Heated Seat Switch Circuit Test

1. Ignition OFF, disconnect the harness connector at the passenger seat lumbar adjuster switch.
2. Test for less than 5 Ω 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. Connect a test lamp between the ignition circuit terminal C and the signal circuit terminal D.
5. Buckle and unbuckle the passenger seat belt. The test lamp should be OFF when buckled and ON when unbuckled.

⇒ | If the test lamp is always OFF, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the seat belt buckle.

⇒ | If the test lamp is always ON, test the signal circuit for a short to ground. If the circuit tests normal, replace the seat belt buckle.

6. If all circuits test normal, test or replace the passenger seat lumbar adjuster switch.

#### Heated Seat Circuit Test

1. Ignition OFF, disconnect the harness connector at the appropriate heated seat module.
2. Test for less than 5 Ω between the ground circuit terminal 4 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 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.

4. Ignition OFF, test for 5.39 k - 6.49 kΩ between the signal circuit terminal 6 and ground with the heated seat switch in the HIGH heat position.

⇒ | If less than the specified value, test the signal circuit for a short to ground. If the signal circuit tests normal, test or replace the lumbar adjuster switch.

⇒ | If greater than the specified value, test the signal circuit for an open/high resistance. If the signal circuit tests normal, test or replace the lumbar adjuster switch.

5. Test for 7.14 k - 8.73 kΩ between the signal circuit terminal 6 and ground with the heated seat switch in the LOW heat position.

⇒ | If not within the specified range, test or replace the lumbar adjuster switch.

6. Test for 2 k - 30 kΩ between the signal circuit terminal 2 and the ground circuit terminal 4.

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

7. Disconnect the harness connector at the seat back heater element.
8. Test for less than 5 Ω between the ground circuit terminal B and ground.

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

9. At the seat back heater element; test for 1.5 - 5 Ω between terminal A and terminal B.

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

10. Connect the harness connector at the seat back heater element.
11. At the heated seat module connector; test for 1.5 - 5 Ω between the control circuit terminal 7 and ground.

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

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

### Component Test

#### Heated Seat Switch

1. Ignition OFF, disconnect the harness connector at the appropriate seat lumbar adjuster switch.
2. Test for infinite resistance between the terminals listed below with the switch in the open position.

• | Signal terminal B and ignition terminal C

• | Ignition terminal C and ground terminal A

⇒ | If not the specified value, replace the lumbar adjuster switch.

3. Test for 2.5 kΩ between the signal terminal B and the ignition terminal C with the switch in the HIGH heat position.

⇒ | If not the specified value, replace the lumbar adjuster switch.

4. Test for 4.9 kΩ between the signal terminal B and the ignition terminal C with the switch in the LOW heat position.

⇒ | If not the specified value, replace the lumbar adjuster switch.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Driver or Passenger Seat Back Cushion Heater Replacement

• | Driver or Passenger Seat Cushion Heater Replacement

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