Heated/Cooled Seats Inoperative
Heated/Cooled Seats Inoperative
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
Each seat has two ventilation heating and cooling modules, one located under the seat cushion to control cushion temperature and one located in the seat back to control seat back temperature.
Each ventilation heating and cooling module contains the necessary electronics to control the heating and cooling functions, as well as a thermo-electric device (TED) and blower motor used for the cooling functions. The heating function is provided by a separate heating element which is also controlled by the ventilation heating and cooling module.
In the description below, the TEDs and blower motors are referenced independently even though they are packaged together as indicated above.
The heated and cooled seat switches are located on the door panels. When a heated or cooled seat switch is pressed, a low reference signal is applied through the switch signal circuit to the door lock/window switch. In response to this signal, the door lock/window switch simultaneously illuminates the appropriate heated/cooled switch indicators and sends a serial data message to the memory seat module (MSM) indicating the heat or cool seat request. The MSM then sends a low side pulse width modulation (PWM) signal through the heated/cooled seat mode signal circuit to both ventilation and cooling modules for a given seat.
Battery positive voltage is supplied to the ventilation heating and cooling modules through a fuse located in the I/P fuse block.
When a cooled seat request is received, the seat ventilation heating and cooling modules apply voltage to the TEDs and a pre-determined voltage to the blower motors. When a heated seat request is received, the seat ventilation heating and cooling modules apply battery voltage and ground through the control circuits to the seat heating elements. In order to determine seat temperature, each ventilation module supplies a 5 V signal and a low reference to the temperature sensors that are attached to the seat cushion and seat back heater elements. The temperature sensors are variable resistors, their resistance changes as the temperature of the seat changes. Then based on the seat temperature, the ventilation module controls the voltage level that it applies to the TED and blower motor when in the cool mode, or it cycles the power supply to the heater element ON and OFF when in the heat mode.
Reference Information
Schematic Reference
Heated/Cooled Seat Schematics [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views 1-2 Shift Solenoid (SS) Valve (M30)
Description and Operation
Heated/Cooled Seats Description and Operation Heated/Cooled Seats
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 the appropriate scan tool Driver or Passenger Door Switch parameters listed below change between Inactive and Active or Off and ON when pressing the appropriate switch.
* Seat Back Heat Mode Sw.
* Seat Cool Mode Switch
* Seat Heat Mode Sw.
• If any parameter does not change
Refer to Component Testing - Heated and Cooled Seat Switch.
• If all parameters change
3. Verify the heated/cooled seat switch indicators turn ON and OFF when pressing the heated and cooled seat switch,
• If any indicator does not turn ON and OFF
Refer to Component Testing - Heated and Cooled Seat Switch.
• If all indicators turn ON and OFF
4. Verify the heated and cooled seat functions listed below operate in all three modes of operation:
* Seat back and cushion heat mode
* Seat back only heat mode
* Seat cool mode
• If both the heat and cooled seat functions are inoperative
Refer to Circuit/System Testing - Heated and Cooled Seat Circuit Test.
• If just the heat function is inoperative
Refer to Circuit/System Testing - Heated Seat Circuit Test.
• If just the cooled seat function is inoperative
Replace the seat heating and cooling ventilation module.
• If both the heat and cooled seat functions operate
5. All OK
Circuit/System Testing
Heated and Cooled Seat Circuit Test
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 seat cushion or seat back ventilation heating and cooling module. It may take up to 2 minutes for all vehicle systems to power down.
2. Test for less than 10 ohms between the ground circuit terminal C and ground.
• If 10 ohms or greater
1. Ignition OFF.
2. Test for less than 2 ohms in the ground circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, repair the open/high resistance in the ground connection.
• If less than 10 ohms
3. Ignition ON.
4. Verify a test lamp illuminates between the B+ circuit terminal A and ground.
• If the test lamp does not illuminate and the circuit fuse is good
Test for less than 2 ohms in the B+ circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, verify the circuit fuse is not open and there is voltage at the fuse.
• If the test lamp does not illuminate and the circuit fuse is open
1. Ignition OFF.
2. Test for infinite resistance between the B+ circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the appropriate seat cushion or seat back ventilation heating and cooling module.
• If the test lamp illuminates
5. Connect a test lamp between the signal circuit terminal B and B+, ignition ON.
6. Verify the test lamp turns ON while the pressing the HEAT or COOL seat switch through the high, medium, and low positions until the OFF position is reached.
• If the test lamp does not turn ON
1. Ignition OFF, disconnect the X6 harness connector at the memory seat module, ignition ON.
2. Test for less than 1 V between the signal circuit and ground.
• If greater than 1 V, repair the short to voltage on the circuit.
• If less than 1 V
3. Test for less than 2 ohms in the signal circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the memory seat module.
• If the test lamp does not turn OFF
1. Ignition OFF, disconnect the X6 harness connector at the memory seat module.
2. Test for infinite resistance between the signal circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the memory seat module.
• If the test lamp turns ON and OFF
7. Test for 500 ohms-300 kohms between the signal circuit terminal D and the low reference circuit terminal E.
• If less than 500 ohms
1. Ignition OFF, disconnect the harness connector at the seat heating element.
2. Test for infinite resistance between the signal and low reference circuits.
• If less than infinite resistance, repair the short between the circuits.
• If infinite resistance, test or replace the seat heating element.
• If greater than 300 kohms
1. Ignition OFF, disconnect the harness connector at the seat heating element.
2. Test for less than 2 ohms in the signal and low reference circuits end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the seat heating element.
• If between 500 ohms-300 kohms
8. Ignition OFF, connect the harness connector at the seat ventilation heating and cooling ventilation module and disconnect the harness connector at the seat heating element.
9. Ignition ON.
10. Test for 4.8-5.2 V between the signal circuit terminal C and ground.
• If less than 4.8 V
1. Ignition OFF, disconnect the harness connector at the ventilation heating and cooling module.
2. Test for infinite resistance between the signal circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for less than 2 ohms in the signal circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the ventilation heating and cooling module.
• If greater than 5.2 V
1. Ignition OFF, disconnect the harness connector at the ventilation heating and cooling module, ignition ON.
2. Test for less than 1 V between the signal circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the ventilation heating and cooling module.
• If between 4.8-5.2 V
11. Replace the seat ventilation heating and cooling ventilation module.
Heated Seat Circuit Test
Note: Circuit/System Verification must be performed before proceeding with Circuit/System Testing.
1. Ignition OFF, disconnect the harness connector at the appropriate seat cushion or seat back ventilation heating and cooling module.
2. Test for 3-8 ohms between control circuit terminal F and control circuit terminal G.
• If less than 3 ohms
1. Ignition OFF, disconnect the harness connector at the seat heating element.
2. Test for infinite resistance between the control circuits.
• If less than infinite resistance, repair the short between the control circuits.
• If infinite resistance, replace the seat heating element.
• If greater than 8 ohms
1. Ignition OFF, disconnect the harness connector at the seat heating element.
2. Test for less than 2 ohms in the control circuits end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, test or replace the seat heating element.
• If between 3-8 ohms
3. Test for Infinite resistance between the control circuit terminal F and ground.
• If less than infinite resistance
Repair the short to ground on the circuit.
• If infinite resistance
4. Ignition ON.
5. Test for less than 1 V between the control circuit terminal G and ground.
• If 1 V or greater
Repair the short to voltage on the circuit.
• If less than 1 V
6. Replace the seat ventilation heating and cooling ventilation module.
Component Testing
Heated and Cooled Seat Switch
1. Ignition OFF, disconnect the X4 harness connector at the appropriate door lock/window switch.
2. Test for infinite resistance between the low reference circuit terminal 4 and the signal terminals listed below with the switch in the open position.
* Seat back and cushion heat switch terminal 6
* Seat back only mode heat switch terminal 7
* Seat cool switch terminal 3
• If less than infinite resistance
Replace the heated and cooled seat switch
• If infinite resistance
3. Test for less than 2 omhs between the low reference circuit terminal 4 and the signal terminals listed below with the appropriate switch in the closed position.
* Seat back and cushion heat switch terminal 6
* Seat back only mode heat switch terminal 7
* Seat cool switch terminal 3
• If 2 omhs or greater
Replace the heated and cooled seat switch
• If less than 2 omhs
4. Install a 3 A fused jumper wire between the low reference circuit terminal 4 and ground.
5. Verify the appropriate indicator illuminates when connecting a test lamp between B+ and each control terminal listed below:
* Seat back only mode indicator terminal 11
* Seat cool mode indicator terminal 12
* Seat back and cushion indicator terminal 10
* Low temperature indicator terminal 9
* Medium temperature indicator terminal 1
* High temperature indicator terminal 2
• If any indicator does not illuminate
Replace the heated and cooled seat switch
• If all indicators illuminate
6. Replace the door lock/window switch.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Driver or Passenger Seat Back Ventilation Heating and Cooling Blower Replacement (Denali with KB6) Driver or Passenger Seat Back Ventilation Heating and Cooling Blower Replacement (Denali with KB6)
* Driver or Passenger Seat Cushion Ventilation Heating and Cooling Blower Replacement (Denali with KB6) Driver or Passenger Seat Cushion Ventilation Heating and Cooling Blower Replacement (Denali with KB6)
* Control Module References Control Module References for the memory seat module and door lock/window switch replacement, programming and setup