Vented Seat Malfunction
Vented Seat Malfunction
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
Diagnostic Fault Information
Circuit/System Description
With the ignition in the ON position, ignition voltage is applied to the ignition main relay energizing the relay. With the relay energized, battery voltage is applied through the switch side of the relay, a 10 A fuse, and the ignition circuit to the driver and passenger vented seat blower motors. The driver and passenger vented seats are controlled by separate vented seat switches located in the radio/HVAC controls. When a vented seat switch is pressed, a serial data message is sent from the radio/HVAC controls to the HVAC control module indicating the vented seat command. The HVAC control module serves as a gateway to transmit the message to the seat memory control module via the serial data line. In response to this message, the seat memory control 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 seat memory control module then sends a serial data message back to the HVAC control module to gateway the information back to the radio/HVAC controls to either illuminate or turn off the appropriate switch indicator.
Reference Information
Schematic Reference
Heated/Cooled Seat Schematics Electrical Diagrams
Connector End View Reference
Component Connector End Views Fuel Pump and Level Sensor Assembly
Description and Operation
Heated/Vented Seat Description and Operation Description and Operation
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
Scan Tool Reference
Control Module References Control Module References for scan tool information
Circuit/System Verification
1. Ignition ON.
2. Verify each scan tool Seat Memory Control Module parameter listed below changes between Vent/Cool and Off when pressing the appropriate vented seat switch.
* Driver Seat Heating/Venting/Cooling Mode
* Passenger Front Seat Heating/Venting/Cooling Mode
• If either parameter does not change
Replace the A20 Radio/HVAC Controls.
• If each parameter changes
3. Refer to Circuit/System Testing.
Circuit/System Testing
Note: Circuit/System Verification must be performed before proceeding with Circuit/System Testing
1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the appropriate blower motor listed below. It may take up to 2 minutes for all vehicle systems to power down.
* M73A Seat Blower Motor - Driver Back
* M73C Seat Blower Motor - Driver Cushion
* M73B Seat Blower Motor - Passenger Back
* M73D Seat Blower Motor - Passenger Cushion
2. Test for less than 5 omhs between the ground circuit terminal B and ground.
• If 5 omhs or greater
1. Ignition OFF.
2. Test for less than 2 omhs in the ground circuit end to end.
• If 2 omhs or greater, repair the open/high resistance in the circuit.
• I less than 2 omhs, repair the open/high resistance in the ground connection.
• If less than 5 omhs
3. Ignition ON.
4. Verify a test lamp illuminates between the ignition circuit terminal C and ground.
• If the test lamp does not illuminate and the circuit fuse is good
1. Ignition OFF.
2. Test for less than 2 ohms in the ignition circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, refer to Power Mode Mismatch Power Mode Mismatch.
• If the test lamp does not illuminate and the circuit fuse is open
1. Ignition OFF.
2. Test for infinite resistance between the ignition circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, test or replace the appropriate component/module listed below.
* M73A Seat Blower Motor - Driver Back
* M73C Seat Blower Motor - Driver Cushion
* M73B Seat Blower Motor - Passenger Back
* M73D Seat Blower Motor - Passenger Cushion
* K50 Rear Window Sunshade Module
• If the test lamp illuminates
5. Connect a test lamp between the control circuit terminal A and B+.
6. Verify the test lamp turns ON when pressing the vented seat switch through the high, medium, and low positions then turns OFF when the off position is reached.
• If the test lamp is always OFF
1. Ignition OFF, disconnect the X1 harness connector at the K40 Seat Memory Control Module, ignition ON.
2. Test for less than 1 V between the control circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V
3. Ignition OFF.
4. Test for less than 2 omhs in the control circuit end to end.
• If 2 omhs or greater, repair the open/high resistance in the circuit.
• If less than 2 omhs, replace the K40 Seat Memory Control Module.
• If the test lamp is always ON
1. Ignition OFF, disconnect the X1 harness connector at the K40 Seat Memory Control Module.
2. Test for infinite resistance between the control circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the K40 Seat Memory Control Module.
7. Test or replace the M73 blower motor.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Radio Control Assembly Replacement Radio Control Assembly Replacement
* Front Seat Vent Fan Replacement Front Seat Vent Fan Replacement
* Front Seat Back Cushion Vent Fan Replacement Front Seat Back Cushion Vent Fan Replacement
* Control Module References Control Module References for K40 Seat Memory Control Module replacement, programming and setup