For 1990-2009 cars

## Vented 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
--- | --- | --- | --- | ---
Ignition Voltage | 1, 4 | 1, 4 | -- | --
Driver Seat Back Blower Motor Ignition Voltage | 1, 4 | 2 | -- | --
Driver Seat Cushion Blower Motor Ignition Voltage | 1, 4 | 3 | -- | --
Driver Vented Seat Signal | 1 | 1 | 1 | --
Driver Seat Back Blower Motor Ground | -- | 2 | -- | --
Driver Seat Cushion Blower Motor Ground | -- | 3 | -- | --
Passenger Seat Back Blower Motor Ignition Voltage | 1, 4 | 5 | -- | --
Passenger Seat Cushion Blower Motor Ignition Voltage | 1, 4 | 6 | -- | --
Passenger Vented Seat Signal | 4 | 4 | 4 | --
Passenger Seat Back Blower Motor Ground | -- | 5 | -- | --
Passenger Seat Cushion Blower Motor Ground | -- | 6 | -- | --
1. Driver vented seat is inoperative 2. Driver vented seat back is inoperative 3. Driver vented seat cushion is inoperative 4. Passenger vented seat is inoperative 5. Passenger vented seat back is inoperative

6. Passenger vented seat cushion is inoperative

### Circuit/System Description

The driver and passenger vented seats are controlled by separate vented seat switches located in the HVAC control panel. Ignition voltage is supplied to the driver and passenger seat blower motors through the F53UA 10 A fuse located in the underhood fuse block. When a vented seat switch is pressed, a serial data message is sent to the HVAC control module. The HVAC control module then serves as a gateway to transmit the serial data message to the memory seat module indicating the vented seat command. In response to this message, the memory seat module applies a low side pulse width modulation (PWM) signal through the blower motor control circuits to the seat cushion and seat back blower motors indicating the vented seat command. The logic in the blower motors then sets the blower speed to the switch set point. Both blower motors run drawing cabin air around and away from occupant. The memory seat module then sends a serial data message back to the HVAC control module to gateway the information back to the HVAC control panel to either illuminate or turn off the appropriate switch 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 Cooled Seat Button parameter while pressing the driver VENTED seat switch. The reading should change between Inactive and Active.

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

2. Observe the scan tool HVAC Passenger Cooled Seat Button parameter while pressing the passenger VENTED seat switch. The reading should change between Inactive and Active.

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

3. If all scan tool readings test normal and the driver and/or passenger vented seat is inoperative, refer to Circuit/System Testing.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the appropriate blower motor listed below:

• | M73A driver seat back blower motor

• | M73C driver seat cushion blower motor

• | M73B passenger seat back blower motor

• | M73D passenger seat cushion blower motor

2. Test for less than 5 Ω between the ground circuit terminal 2 and ground.

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

3. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 1 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 signal circuit terminal 3 and B+.
5. Press the VENTED seat switch through the high, medium, and low positions to OFF. The test lamp should illuminate until the OFF position is reached.

⇒ | If the test lamp does not illuminate, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K40 memory seat module.

⇒ | If the test lamp remains ON with the switch in the OFF position, test the signal circuit for a short to ground. If the circuit tests normal, replace the K40 memory seat module.

6. If all circuits test normal, test or replace the blower motor.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Front Seat Vent Fan Replacement

• | Front Seat Back Cushion Vent Fan Replacement

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

## Vented 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
--- | --- | --- | --- | ---
Ignition Voltage | 1, 4 | 1, 4 | -- | --
Driver Seat Back Blower Motor Ignition Voltage | 1, 4 | 2 | -- | --
Driver Seat Cushion Blower Motor Ignition Voltage | 1, 4 | 3 | -- | --
Driver Vented Seat Signal | 1 | 1 | 1 | --
Driver Seat Back Blower Motor Ground | -- | 2 | -- | --
Driver Seat Cushion Blower Motor Ground | -- | 3 | -- | --
Passenger Seat Back Blower Motor Ignition Voltage | 1, 4 | 5 | -- | --
Passenger Seat Cushion Blower Motor Ignition Voltage | 1, 4 | 6 | -- | --
Passenger Vented Seat Signal | 4 | 4 | 4 | --
Passenger Seat Back Blower Motor Ground | -- | 5 | -- | --
Passenger Seat Cushion Blower Motor Ground | -- | 6 | -- | --
1. Driver vented seat is inoperative 2. Driver vented seat back is inoperative 3. Driver vented seat cushion is inoperative 4. Passenger vented seat is inoperative 5. Passenger vented seat back is inoperative

6. Passenger vented seat cushion is inoperative

### Circuit/System Description

The driver and passenger vented seats are controlled by separate vented seat switches located in the HVAC control panel. Ignition voltage is supplied to the driver and passenger seat blower motors through the F53UA 10 A fuse located in the underhood fuse block. When a vented seat switch is pressed, a serial data message is sent to the HVAC control module. The HVAC control module then serves as a gateway to transmit the serial data message to the heated seat module indicating the vented seat command. In response to this message, the heated seat module applies a low side pulse width modulation (PWM) signal through the blower motor control circuits to the seat cushion and seat back blower motors indicating the vented seat command. The logic in the blower motors then sets the blower speed to the switch set point. Both blower motors run drawing cabin air around and away from occupant. The heated seat module then sends a serial data message back to the HVAC control module to gateway the information back to the HVAC control panel to either illuminate or turn off the appropriate switch 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 Cooled Seat Button parameter while pressing the driver VENTED seat switch. The reading should change between Inactive and Active.

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

2. Observe the scan tool HVAC Passenger Cooled Seat Button parameter while pressing the passenger VENTED seat switch. The reading should change between Inactive and Active.

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

3. If all scan tool readings test normal and the driver and/or passenger vented seat is inoperative, refer to Circuit/System Testing.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the appropriate blower motor listed below:

• | M73A driver seat back blower motor

• | M73C driver seat cushion blower motor

• | M73B passenger seat back blower motor

• | M73D passenger seat cushion blower motor

2. Test for less than 5 Ω between the ground circuit terminal 2 and ground.

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

3. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 1 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 signal circuit terminal 3 and B+.
5. Press the VENTED seat switch through the high, medium, and low positions to OFF. The test lamp should illuminate until the OFF position is reached.

⇒ | If the test lamp does not illuminate, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K29 heated seat module.

⇒ | If the test lamp remains ON with the switch in the OFF position, test the signal circuit for a short to ground. If the circuit tests normal, replace the K29 heated seat module.

6. If all circuits test normal, test or replace the blower motor.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Front Seat Vent Fan Replacement

• | Front Seat Back Cushion Vent Fan Replacement

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