For 1990-2009 cars

## Heated Seat Inoperative With Memory A45

### 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 Back Only Mode Switch Signal | 2 | 2 | 2 | --
Heated Seat Temperature Switch Signal | 1 | 1 | 1 | --
Heated Seat Back Only Indicator Control | 3 | 3 | 4 | --
Heated Seat Back/Cushion Indicator Control | 3 | 3 | 4 | --
Heated Seat High Temperature Indicator Control | 3 | 3 | 4 | --
Heated Seat Low Temperature Indicator Control | 3 | 3 | 4 | --
Heated Seat Medium Temperature Indicator Control | 3 | 3 | 4 | --
Ground - Heated Seat Switch | 1 | 1, 2, 3 | -- | --
1. Heated seat malfunction 2. Heated seat back only mode malfunction 3. Heated seat switch indicator inoperative 4. Heated seat switch indicator always on

### Circuit/System Description

The driver and front passenger heated seats are controlled by separate heated seat switches. When a heated seat switch is pressed, ground is momentarily applied through the switch contacts and the switch signal circuit to the door switch. In response to this signal, the door switch sends serial data a message to the memory seat module (MSM) indicating the heat seat request. The door switch then applies voltage through the appropriate indicator control circuits to the heated seat switch illuminating the indicators.

### 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

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

1. Ignition ON, observe the appropriate scan tool driver or passenger door switch parameters listed below while pressing and releasing the appropriate heated seat switch. The readings should change between Inactive and Active.

• | Seat Heat Mode Sw.

• | Seat Back Heat Mode Sw.

⇒ | If not the specified value, refer to Circuit/System Testing.

2. If all heated seat switch functions operate OK, but, one or more of the heated seat switch indicators is inoperative or is always ON, refer to Heated Seat Switch Indicator Malfunction.
3. If all scan tool parameters test normal and there are no DTCs set, replace the MSM.

### Circuit/System Testing

#### Heated Seat Switch Malfunction

1. Ignition OFF, disconnect the harness connector at the appropriate heated seat switch.
2. Ignition OFF, test for less than 10 ohms between the ground circuit terminal 7 and ground.

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

3. Ignition ON, verify the scan tool Seat Heat Mode Sw. parameter is Inactive.

⇒ | If not the specified value, test the signal circuit terminal 4 for a short to ground. If the circuit tests normal, replace the appropriate driver or passenger door module.

4. Verify the scan tool Seat Back Heat Mode Sw. parameter is Inactive.

⇒ | If not the specified value, test the signal circuit terminal 5 for a short to ground. If the circuit tests normal, replace the appropriate driver or passenger door module.

5. Install a 3A fused jumper wire between the signal circuit terminal 4 and ground. Verify the scan tool Seat Heat Mode Sw. parameter is Active.

⇒ | If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the appropriate driver or passenger door module.

6. Install a 3A fused jumper wire between the signal circuit terminal 5 and ground. Verify the scan tool Seat Back Heat Mode Sw. parameter is Active.

⇒ | If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the appropriate driver or passenger door module.

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

#### Heated Seat Switch Indicator Malfunction

1. Ignition OFF, disconnect the harness connector at the appropriate heated seat switch.
2. Ignition ON, connect a test lamp between the control circuits listed below and ground. Command the appropriate driver or passenger door switch Heated Seat Indicator ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

• | Back and cushion heat indicator terminal 1

• | Low heat indicator terminal 6

• | Medium heat indicator terminal 8

• | Back heat indicator terminal 9

• | High heat indicator terminal 10

⇒ | If the test lamp is always ON, test the appropriate control circuit for a short to voltage. If the circuit tests normal, replace the door module.

⇒ | If the test lamp is always OFF, test the appropriate control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the door module.

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

### Component Testing

#### Heated Seat Switch

1. Ignition OFF, disconnect the harness connector at the heated seat switch switch.
2. Test for infinite resistance between the signal terminal 4 and the ground terminal 7 with the back and cushion switch in the open position.

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

3. Test for infinite resistance between the signal terminal 5 and the ground terminal 7 with the back only switch in the open position.

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

4. Test for less than 2 ohms between the signal terminal 4 and the ground terminal 7 with the back and cushion switch in the closed position.

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

5. Test for less than 2 ohms between the signal terminal 5 and the ground terminal 7 with the back only switch in the closed position.

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

6. Install a 3A fused jumper wire between the ground terminal 7 and ground.
7. Connect a test lamp between the control circuits listed below and B+. The selected switch indicator should illuminate.

• | Back and cushion heat indicator terminal 1

• | Low heat indicator terminal 6

• | Medium heat indicator terminal 8

• | Back heat indicator terminal 9

• | High heat indicator terminal 10

⇒ | If any indicator does not illuminate, replace the heated seat switch.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Driver or Passenger Seat Heater Switch Replacement

• | Control Module References for MSM and driver or passenger door switch replacement, programming, and setup

## Heated Seat Inoperative Without Memory A45

### 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 Switch Indicator Supply Voltage | 3 | 3 | -- | --
Heated Seat Back Only Mode Switch Signal | 2 | 2 | 2 | --
Heated Seat Temperature Switch Signal | 1 | 1 | 1 | --
Heated Seat Back Only Indicator Control | 4 | 3 | 3 | --
Heated Seat Back/Cushion Indicator Control | 4 | 3 | 3 | --
Heated Seat High Temperature Indicator Control | 4 | 3 | 3 | --
Heated Seat Low Temperature Indicator Control | 4 | 3 | 3 | --
Heated Seat Medium Temperature Indicator Control | 4 | 3 | 3 | --
Ground - Heated Seat Switch | 1 | 1 | -- | --
1. Heated seat malfunction 2. Heated seat back only mode malfunction 3. Heated seat switch indicator inoperative 4. Heated seat switch indicator always on

### Circuit/System Description

The driver and front passenger heated seats are controlled by separate heated seat switches. When a heated seat switch is pressed, ground is momentarily applied through the switch contacts and the switch signal circuit to the heated seat module (HSM). In response to this signal, the module then applies battery voltage through the element supply voltage circuits to the seat cushion and seat back heating elements. The HSM then supplies a ground through the appropriate indicator control circuits to the heated seat switch illuminating the switch indicators.

### 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

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

1. Ignition ON, observe the appropriate scan tool Heated Seat Module parameter listed below while pressing and releasing the heated seat back and cushion switch. The readings should change between Off and Back and Cushion.

• | Driver Seat HVC Mode

• | Passenger Seat HVC Mode

⇒ | If not the specified value, refer to Heated Seat Switch Malfunction.

2. Ignition ON, observe the appropriate scan tool Heated Seat Module parameter listed below while pressing and releasing the heated seat back only switch. The readings should change between Off and Back Only.

• | Driver Seat HVC Mode

• | Passenger Seat HVC Mode

⇒ | If not the specified value, refer to Heated Seat Switch Malfunction.

3. If all heated seat switch functions operate OK, but, one or more of the heated seat switch indicators is inoperative or always ON, refer to Heated Seat Switch Indicator Malfunction.
4. If all scan tool parameters test normal and there are no DTCs set, replace the HSM.

### Circuit/System Testing

#### Heated Seat Switch Malfunction

1. Ignition OFF, disconnect the harness connector at the appropriate heated seat switch.
2. Test for less than 10 ohms between the ground circuit terminal 7 and ground.

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

3. Ignition ON, verify the appropriate scan tool Heated Seat Module parameter listed below is OFF.

• | Driver Seat HVC Mode

• | Passenger Seat HVC Mode

⇒ | If not the specified value, test the signal circuits listed below for a short to ground. If the circuits test normal, replace the HSM.

• | Seat cushion and back signal terminal 4

• | Seat back only signal terminal 5

4. Install a 3A fused jumper wire between the signal circuit terminal 4 and ground. Verify the appropriate scan tool Heated Seat Module parameter listed below is Back and Cushion.

• | Driver Seat HVC Mode

• | Passenger Seat HVC Mode

⇒ | If not the specified value, test the signal circuit for a short to voltage an open/high resistance. If the circuit tests normal, replace the HSM.

5. Install a 3A fused jumper wire between the signal circuit terminal 5 and ground. Verify the appropriate scan tool Heated Seat Module parameter listed below is Back Only.

• | Driver Seat HVC Mode

• | Passenger Seat HVC Mode

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

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

#### Heated Seat Switch Indicator 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 control circuit terminal 2 and ground. If the test lamp does not illuminate, refer to Interior Backlighting Malfunction.
3. Ignition OFF, connect the harness connector at the heated seat switch.
4. Disconnect the X3, X4 harness connectors at the heated seat module.
5. Ignition ON, connect a test lamp between the control circuits listed below and ground. The appropriate indicator should turn ON and OFF when the test lamp is connected and disconnected

• | High heat indicator terminal 5 X3

• | Medium heat indicator terminal 16 X4

• | Low heat indicator terminal 4 X3

• | Back and cushion heat indicator terminal 17 X4

• | Back heat indicator terminal 15 X4

⇒ | If the test lamp is always ON, test the appropriate control circuit for a short to ground. If the circuit tests normal, test or replace the heated seat switch.

⇒ | If the test lamp is always OFF, test the appropriate control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, test or replace the heated seat switch.

6. If all circuits test normal, replace the door module.

### Component Testing

#### Heated Seat Switch

1. Ignition OFF, disconnect the harness connector at the heated seat switch switch.
2. Test for infinite resistance between the signal terminal 4 and the ground terminal 7 with the back and cushion switch in the open position.

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

3. Test for infinite resistance between the signal terminal 5 and the ground terminal 7 with the back only switch in the open position.

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

4. Test for less than 5 ohms between the signal terminal 4 and the ground terminal 7 with the back and cushion switch in the closed position.

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

5. Test for less than 5 ohms between the signal terminal 5 and the ground terminal 7 with the back only switch in the closed position.

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

6. Install a 3A fused jumper wire between the control terminal 2 and B+.
7. Connect a test lamp between the control circuits listed below and ground. The selected indicator should illuminate.

• | Back and cushion heat indicator terminal 1

• | Low heat indicator terminal 6

• | Medium heat indicator terminal 8

• | Back heat indicator terminal 9

• | High heat indicator terminal 10

⇒ | If any indicator does not illuminate, replace the heated seat switch.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Driver or Passenger Seat Heater Switch Replacement

• | Control Module References for HSM replacement, setup, and programming

## Heated Seat Inoperative With Memory A45 and KB6

### 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
--- | --- | --- | --- | ---
MSM B+ Terminal 5 X3 | B2425 0D, B2430 0D 1 | B2425 0D, B2430 0D 1 | -- | --
Heated Seat Switch Back/Cushion Signal | 1 | 1 | 1 | --
Heated Seat Switch Cool Mode Signal | 2 | 2 | 2 | --
Heated Seat Cool Indicator Control | 3 | 3 | 4 | --
Heated Seat Back/Cushion Indicator Control | 3 | 3 | 4 | --
Heated Seat High Indicator Control | 3 | 3 | 4 | --
Heated Seat Low Indicator Control | 3 | 3 | 4 | --
Heated Seat Medium Indicator Control | 3 | 3 | 4 | --
Heated and Cooled Seat Switch Ground | 1 | 1, 2, 3 | -- | --
Driver Heated Seat Element Supply Voltage | B2508 02 | B2425 0D | B2508 01 | B2425 0B, B2425 0C, B2425 0E
Driver Heated Seat Element Control | B2508 02 | B2425 0D | B2508 01 | B2425 0B, B2425 0C, B2425 0E
Driver Heated Seat Cushion Temperature Sensor Signal | B1925 02 | B1925 05 | B1925 05 | --
Driver Heated Seat Cushion Temperature Sensor Low Reference | -- | B1925 05 | -- | --
Passenger Heated Seat Element Supply Voltage | B2508 02 | B2430 0D | B2508 01 | B2430 0B, B2430 0C, B2430 0E
Passenger Heated Seat Element Control | B2508 02 | B2430 0D | B2508 01 | B2430 0B, B2430 0C, B2430 0E
Passenger Heated Seat Cushion Temperature Sensor Signal | B2170 02 | B2170 05 | B2170 05 | --
Passenger Heated Seat Cushion Temperature Sensor Low Reference | -- | B2170 05 | -- | --
1. Heated seat malfunction 2. Heated seat cool mode malfunction 3. Heated seat switch indicator inoperative 4. Heated seat switch indicator always on

### Circuit/System Description

The driver and front passenger heated seats are controlled by separate heated seat switches. When a heated seat switch is pressed, ground is momentarily applied through the switch contacts and the switch signal circuit to the door module. In response to this signal, the door module sends serial data a message to the memory seat module (MSM) indicating the heat seat request. The door module then applies voltage through the appropriate indicator control circuits to the heated seat switch illuminating the indicators.

### 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

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

1. Ignition ON, observe the appropriate scan tool driver or passenger Seat Heat Mode Sw. parameter while pressing and releasing the appropriate heated seat switch. The readings should change between Inactive and Active.

⇒ | If not the specified value, refer to Heated and Cooled Seat Switch Malfunction.

2. If the heated seat switch function operates OK, but, one or more of the heated seat switch indicators is inoperative or is always ON, refer to Heated and Cooled Seat Switch Indicator Malfunction.
3. If all scan tool parameters test normal and there are no DTCs set, replace the MSM.

### Circuit/System Testing

#### Heated and Cooled Seat Switch Malfunction

1. Ignition OFF, disconnect the harness connector at the appropriate heated and cooled seat switch.
2. Ignition OFF, test for less than 10 Ω between the ground circuit terminal 7 and ground.

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

3. Ignition ON, verify the scan tool Seat Heat Mode Sw. parameter is Inactive.

⇒ | If not the specified value, test the signal circuit terminal 4 for a short to ground. If the circuit tests normal, replace the appropriate driver or passenger door module.

4. Install a 3 A fused jumper wire between the signal circuit terminal 4 and ground. Verify the scan tool Seat Heat Mode Sw. parameter is Active.

⇒ | If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the appropriate driver or passenger door module.

5. If all circuits test normal, test or replace the heated and cooled seat switch.

#### Heated and Cooled Seat Switch Indicator Malfunction

1. Ignition OFF, disconnect the harness connector at the appropriate heated and cooled seat switch.
2. Ignition ON, connect a test lamp between the control circuits listed below and ground. Command the appropriate driver or passenger door switch Heated Seat Indicator ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

• | Back and cushion heat indicator terminal 1

• | Low heat indicator terminal 6

• | Medium heat indicator terminal 8

• | High heat indicator terminal 10

⇒ | If the test lamp is always ON, test the appropriate control circuit for a short to voltage. If the circuit tests normal, replace the door module.

⇒ | If the test lamp is always OFF, test the appropriate control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the door module.

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

### Component Testing

#### Heated Seat Switch

1. Ignition OFF, disconnect the harness connector at the heated and cooled seat switch switch.
2. Test for infinite resistance between the signal terminal 4 and the ground terminal 7 with the back/cushion switch in the open position.

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

3. Test for infinite resistance between the signal terminal 5 and the ground terminal 7 with the cool mode switch in the open position.

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

4. Test for less than 2 Ω between the signal terminal 4 and the ground terminal 7 with the back/cushion switch in the closed position.

⇒ | If greater than the specified value, replace the heated and cooled seat switch.

5. Test for less than 2 ohms between the signal terminal 5 and the ground terminal 7 with the cool mode switch in the closed position.

⇒ | If greater than the specified value, replace the heated and cooled seat switch.

6. Install a 3 A fused jumper wire between the ground terminal 7 and ground.
7. Connect a test lamp between the control circuits listed below and B+. The selected switch indicator should illuminate.

• | Back/cushion heat indicator terminal 1

• | Low heat indicator terminal 6

• | Medium heat indicator terminal 8

• | Cool mode indicator terminal 9

• | High heat indicator terminal 10

⇒ | If any indicator does not illuminate, replace the heated and cooled seat switch.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Driver or Passenger Seat Heater Switch Replacement

• | Control Module References for MSM and driver or passenger door switch replacement, programming, and setup