For 1990-2009 cars

## Front Heated Seat Malfunction 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
--- | --- | --- | --- | ---
Memory Seat Module B+ Terminal 5 | B2425 0D, B2430 0D, 1, 2 | B2425 0D, B2430 0D, 1, 2 | -- | --
Driver Heated Seat Element Control Terminal 11 X3 | B242A 02 | B2425 0D | B242A 01 | B2425 0E
Driver Heated Seat Element Control Terminal 6 X3 | B242A 02 | B2425 0D | B242A 01 | B2425 0E
Driver Heated Seat Temperature Sensor Signal | B1925 02 | B1925 05 | B1925 05 | --
Driver Heated Seat Temperature Sensor Low Reference | -- | B1925 05 | -- | --
Passenger Heated Seat Element Control Terminal 10 X3 | B242A 02 | B2430 0D | B242A 01 | B2430 0E
Passenger Heated Seat Element Control Terminal 4 X3 | B242A 02 | B2430 0D | B242A 01 | B2430 0E
Passenger Heated Seat Temperature Sensor Signal | B2170 02 | B2170 05 | B2170 05 | --
Passenger Heated Seat Temperature Sensor Low Reference | -- | B2170 05 | -- | --
1. Power seats inoperative 2. Heated seats inoperative

### Circuit/System Description

The driver and passenger heated seats are controlled by separate heated seat switches located in the HVAC control panel. When a heated seat switch is pressed, a serial data message is sent to the HVAC control module. The HVAC control module serves as a gateway to transmit the serial data message to the memory seat module indicating the heated seat command. In response to this signal, the memory seat module then applies or removes battery voltage through the element supply voltage circuit of the seat heating elements. The memory seat module then sends a serial data message back to the HVAC control module to gateway the information to the HVAC control panel to either illuminate or turn off the appropriate temperature indicator.

### Reference Information

#### Schematic Reference

Heated/Cooled Seat Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Heated/Vented Seat 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 Testing

1. Ignition OFF, disconnect the X4 harness connector at the K40 memory seat module.
2. 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.

3. Ignition OFF, connect the X4 harness connector at the K40 memory seat module.
4. Ignition ON, observe the scan tool HVAC Driver Heated Seat Sw. parameter while pressing the driver HEATED seat switch. The readings should change between Inactive and Active.

⇒ | If not the specified value, replace the A26 HVAC control panel.

5. Observe the scan tool HVAC Pass. Heated Seat Sw. parameter while pressing the passenger HEATED seat switch. The readings should change between Inactive and Active.

⇒ | If not the specified value, replace the A26 HVAC control panel.

6. If the scan tool readings are normal, there are no DTCs set, and the driver and/or passenger heated seat is inoperative, replace the K40 memory seat module.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for memory seat module and HVAC control panel replacement, setup, and programming

## Front Heated Seat Malfunction 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
--- | --- | --- | --- | ---
Driver Heated Seat Element Control Terminal 3 X2 | B242A 02 | B2425 0D | B242A 01 | B2425 0E
Driver Heated Seat Element Control Terminal 1 X2 | B242A 02 | B2425 0D | B242A 01 | B2425 0E
Driver Heated Seat Temperature Sensor Signal | B1925 02 | B1925 05 | B1925 05 | --
Driver Heated Seat Temperature Sensor Low Reference | -- | B1925 05 | -- | --
Passenger Heated Seat Element Control Terminal 5 X2 | B242A 02 | B2430 0D | B242A 01 | B2430 0E
Passenger Heated Seat Element Control Terminal 2 X2 | B242A 02 | B2430 0D | B242A 01 | B2430 0E
Passenger Heated Seat Temperature Sensor Signal | B2170 02 | B2170 05 | B2170 05 | --
Passenger Heated Seat Temperature Sensor Low Reference | -- | B2170 05 | -- | --

### Circuit/System Description

The driver and passenger heated seats are controlled by separate heated seat switches located in the HVAC control panel. When a heated seat switch is pressed, a serial data message is sent to the HVAC control module. The HVAC control module serves as a gateway to transmit the serial data message to the heated seat module indicating the heated seat command. In response to this signal, the heated seat module then applies or removes battery voltage through the element supply voltage circuit of the seat heating elements. The heated seat module then sends a serial data message back to the HVAC control module to gateway the information to the HVAC control panel to either illuminate or turn off the appropriate temperature indicator.

### Reference Information

#### Schematic Reference

Heated/Cooled Seat Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Heated/Vented Seat 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 scan tool HVAC Driver Heated Seat Sw. parameter while pressing the driver HEATED seat switch. The readings should change between Inactive and Active.

⇒ | If not the specified value, replace the A26 HVAC control panel.

2. Observe the scan tool HVAC Pass. Heated Seat Sw. parameter while pressing the passenger HEATED seat switch. The readings should change between Inactive and Active.

⇒ | If not the specified value, replace the A26 HVAC control panel.

3. If all scan tool readings are normal, there are no DTCs set, and the driver and/or passenger heated seat is inoperative, replace the K29 heated seat module.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for heated seat module and HVAC control panel replacement, setup, and programming