Vented Seat Malfunction (Without Memory A45)
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Vented Seat Malfunction (Without Memory A45)
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Diagnostic Fault Information
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Circuit
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Short to Ground
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Open/High Resistance
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Short to Voltage
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Signal Performance
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Ignition Voltage
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1, 4
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1, 4
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-
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-
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Driver Seat Back Blower Motor Ignition Voltage
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1, 4
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2
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-
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-
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Driver Seat Cushion Blower Motor Ignition Voltage
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1, 4
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3
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-
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-
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Driver Vented Seat Signal
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1
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1
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1
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-
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Driver Seat Back Blower Motor Ground
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-
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2
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-
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-
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Driver Seat Cushion Blower Motor Ground
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-
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3
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-
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-
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Passenger Seat Back Blower Motor Ignition Voltage
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1, 4
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5
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-
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-
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Passenger Seat Cushion Blower Motor Ignition Voltage
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1, 4
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6
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-
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-
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Passenger Vented Seat Signal
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4
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4
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4
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-
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Passenger Seat Back Blower Motor Ground
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-
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5
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-
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-
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Passenger Seat Cushion Blower Motor Ground
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-
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6
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-
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-
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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
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Circuit/System Description
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The driver and passenger vented seats are controlled by separate vented seat switches located together with the radio/HVAC control. Ignition voltage is supplied to the driver and passenger seat blower motors through a 15 A fuse that is located in the rear fuse block. 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 heating control module via the serial data line. In response to this message, the seat heating 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 heating 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.
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
Scan Tool Reference
Control Module References
for scan tool information
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Circuit/System Verification
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1.
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Ignition ON, observe the scan tool Driver Seat Heating/Venting/Cooling Mode parameter while pressing the driver VENTED seat switch. The reading should change between Off and Vent/Cool.
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2.
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If not the specified value, replace the A20 radio/HVAC controls.
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3.
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Check the scan tool Passenger Seat Heating/Venting/Cooling Mode parameter while pressing the passenger seat VENTILATION switch. The reading should change between Off and Vent/Cool.
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4.
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If not the specified value, replace the A20 radio/HVAC controls.
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5.
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If all scan tool parameter readings test normal and the driver and/or passenger vented seat is inoperative, refer to Circuit/System Testing.
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1.
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Ignition OFF, disconnect the harness connector at the appropriate blower motor listed below:
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•
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M73A seat blower motor - driver back
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•
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M73C seat blower motor - driver cushion
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•
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M73B seat blower motor - passenger back
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•
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M73D seat blower motor - passenger cushion
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2.
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Test for less than 10 Ω between the ground circuit terminal B and ground.
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3.
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If greater than the specified range, test the ground circuit for an open/high resistance.
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4.
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Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal C and ground.
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5.
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If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.
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6.
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Connect a test lamp between the control circuit terminal A and B+.
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7.
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Ignition ON, 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.
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8.
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If the test lamp does not illuminate, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K29 seat heating control module.
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9.
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If the test lamp remains ON with the switch in the OFF position, test the control circuit for a short to ground. If the circuit tests normal, replace the K29 seat heating control module.
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10.
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If all circuits test normal, test or replace the M73 blower motor.
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Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.
