Heated/Cooled Seats Inoperative 2
Heated/Cooled Seats Inoperative
Passenger Heated/Cooled Seat Inoperative
1. Ignition ON, observe the following scan tool parameters in the Passenger Door Switch data list while pressing and releasing the related switch. The readings should change between Active and Inactive.
* Seat Back Heat Mode Sw.
* Seat Cool Mode Switch
* Seat Heat Mode Sw.
• If not Active or always Active, perform the Heated and Cooled Seat Switch Component Test.
2. Ignition OFF, disconnect the (C1, C2, C3) harness connectors at the CCS module.
3. Connect a test lamp between the heated/cooled seat mode signal circuit terminal 6 (C3) and battery voltage.
4. Ignition ON, press the HEAT or COOL 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 MSM.
• If the test lamp is ON with the switch in the OFF position, test the signal circuit for a short to ground. If the circuit tests normal, replace the MSM.
Important: If the resistance is measured with the seat still warm or cool, the resistance values will vary. At 68°F (20°C), the nominal resistance value is 1200 ohms & 5 percent. For hotter or colder ambient temperatures, refer to the Temperature vs Resistance table below. The delta resistance values between the seat cushion and seat back temperature sensors should not be greater than 2000 ohms.
5. Test for 300 - 18K ohms of resistance between the following temperature sensor signal and low reference circuits. The resistance should measure near the specified value in the Temperature vs Resistance table below.
* Connector C2 seat cushion temperature sensor signal circuit terminal 2 and low reference circuit terminal 3.
* Connector C2 seat back temperature sensor signal circuit terminal 4 and low reference circuit terminal 5.
• If the resistance is greater than the specified value, test the sensor signal circuit and low reference circuit for a short to voltage or an open/high resistance. If the circuits test normal, test or replace the appropriate ventilation heat and cool module.
• If the resistance measures less than the specified value, test or replace the appropriate ventilation heat and cool module.
Important: The test leads must be connected in the correct polarity, otherwise lower out of range values will appear. Use the Positive Lead for the COOL control circuit and the Negative Lead for the HEAT control circuit. If the resistance is measured with the seat still warm or cool, the resistance values will vary even if the system was powered up for just a few seconds. The TED must be allowed to stabilize to room temperature prior to a measurement. The following conditions will change the resistance to out of range values:
* The test leads are incorrectly connected
* Air blowing across the TED.
* Measuring the resistance at other than room temperature of 70°F (21°C).
* Holding the TED portion of the heated and cool ventilation module in your hand.
In hotter or colder climates where room temperature conditions of 70°F (21°C) may be unattainable, resistance values may read above the specified range. Use a heat gun or a blower to warm or cool the TED while measuring the resistance. The resistance values should slowly lower toward the specified range.
Test for 0.9-10 ohms of resistance between the following heat control and cool control circuits.
* Connector C1 seat cushion heat control circuit terminal A and cool control circuit terminal B.
* Connector C1 seat back heat control circuit terminal C and cool control circuit terminal D.
• If greater than 10 ohms, test the control circuits for an open/high resistance. If the circuits test normal, test or replace the appropriate ventilation heat and cool module.
• If less than 0.9 ohms, test or replace the appropriate ventilation heat and cool module.
6. Test for infinite resistance between the following circuits and ground.
* Connector C1:
- Seat cushion heat control circuit terminal A
- Seat cushion cool control circuit terminal B
- Seat back heat control circuit terminal C
- Seat back cool control circuit terminal D
* Connector C2:
- Seat cushion temperature sensor signal circuit terminal 2
- Seat back temperature sensor signal circuit terminal 4
* Connector C3:
- Seat cushion blower motor speed control circuit terminal 3
- Seat back blower motor speed control circuit terminal 4
- Blower motor supply voltage circuit terminal 8
• If less than infinite, test the appropriate circuit for a short to ground.
7. Connect the (C1, C2, C3) harness connectors to the CCS module.
8. Disconnect the harness connector at the seat cushion ventilation heat and cool module.
9. Ignition OFF, test for less than 5 ohms of resistance between the blower motor low reference circuit terminal 4 and ground.
• If greater than 5 ohms, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the climate control module.
10. Ignition ON, test for 4.8-5.2 volts between the temperature sensor signal circuit terminal 5 and ground.
• If greater than 5.2 volts, test the signal circuit for a short to voltage. If the circuit tests normal, replace the CCS module.
• If less than 4.8 volts, replace the CCS module.
Important: The ignition must be cycled OFF then ON between each test in order to reset the CCS module.
11. Ignition ON, connect a test lamp between the following control circuits and ground. The test lamp should illuminate or slowly illuminate for approximately 2 to 4 seconds after the switch is pressed. On the heat control circuit, the test lamp may exhibit a 4 second delay before it starts to illuminate.
Press the HEAT switch for heat control and the COOL switch for cool control.
* Terminal 1 seat cushion heat control circuit
* Terminal 3 seat cushion cool control circuit
• If the test lamp does not illuminate, replace the CCS module.
• If the test lamp is always ON, test the appropriate control circuit for a short to voltage. If the circuit tests normal, replace the CCS module.
Important: The ignition must be cycled OFF then ON between each test in order to reset the CCS module.
12. Connect a test lamp between the following circuits and ground. The test lamp should illuminate or slowly illuminate for approximately 5 seconds after pressing the HEAT switch.
* Terminal 2 seat cushion blower motor supply voltage circuit
* Terminal 7 seat cushion blower motor speed control circuit
• If the test lamp does not illuminate, test the appropriate circuit for an open/high resistance. If the circuit tests normal, replace the CCS module.
• If the test lamp is always ON, test the appropriate circuit for a short to voltage. If the circuit tests normal, replace the CCS module.
13. Connect the harness connector to the seat cushion ventilation heat and cool module.
14. Disconnect the harness connector at the seat back ventilation heat and cool module.
15. Ignition OFF, test for less than 5 ohms of resistance between the blower motor low reference circuit terminal 4 and ground.
• If greater than 5 ohms, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the CCS module.
16. Ignition ON, test for 4.8-5.2 volts between the temperature sensor signal circuit terminal 5 and ground.
• If greater than 5.2 volts, test the signal circuit for a short to voltage. If the circuit tests normal, replace the CCS module.
• If less than 4.8 volts, replace the CCS module.
Important: The ignition must be cycled OFF then ON between each test in order to reset the CCS module.
17. Ignition ON, connect a test lamp between the following control circuits and ground. The test lamp should illuminate or slowly illuminate for approximately 4 seconds after the switch is pressed. On the heat control circuit, the test lamp may exhibit a 4 second delay before it starts to illuminate.
Press the HEAT switch for heat control and the COOL switch for cool control.
* Terminal 1 seat back heat control circuit
* Terminal 3 seat back cool control circuit
• If the test lamp does not illuminate, replace the CCS module.
• If the test lamp is always ON, test the appropriate control circuit for a short to voltage. If the circuit tests normal, replace the CCS module.
Important: The ignition must be cycled OFF then ON between each test in order to reset the CCS module.
18. Connect a test lamp between the following circuits and ground. The test lamp should illuminate or slowly illuminate for approximately 5 seconds after pressing the HEAT switch.
* Terminal 2 seat back blower motor supply voltage
* Terminal 7 seat back blower motor speed control
• If the test lamp does not illuminate, test the appropriate circuit for an open/high resistance. If the circuit tests normal, replace the CCS module.
• If the test lamp is always ON, test the appropriate circuit for a short to voltage. If the circuit tests normal, replace the CCS module.
19. If all circuits test normal, test or replace the appropriate ventilation heat and cool module.
Component Testing
Heated and Cool Seat Switch
1. Ignition OFF, disconnect the (C4) harness connector at the door module.
2. Test for infinite resistance between the following switch signal circuits and the low reference circuit terminal 4 with the switch in the open position.
* Terminal 7 heated seat back only mode switch signal
* Terminal 6 heated seat back cushion heat switch signal
* Terminal 3 heated seat cool switch signal
• If less than infinite resistance, replace the heated and cooled seat switch.
3. Test for less than 2 ohms between the following switch signal circuits and the low reference circuit terminal 4 with the switch in the closed position.
* Terminal 7 heated seat back only mode switch signal
* Terminal 6 heated seat back cushion heat switch signal
* Terminal 3 heated seat cool switch signal
• If greater than 2 ohms for any of the tests, replace the heated and cooled seat switch.
Ventilation Heat and Cool Module
1. Ignition OFF, disconnect the harness connectors at the seat cushion and seat back ventilation heat and cool modules.
Important: If the resistance is measured with the seat still warm or cool, the resistance values will vary. At 68°F (20°C), the nominal resistance value is 1200 ohms ±5 percent. For hotter or colder ambient temperatures, refer to the Temperature vs Resistance table below. The delta resistance values between the seat cushion and seat back temperature sensors should not be greater than 2000 ohms.
2. Test for 300 ohms - 18K ohms of resistance between the temperature sensor signal circuit terminal 5 and the low reference circuit terminal 8.
• If the resistance is not within the specified range, replace the ventilation heat and cool module.
Important: The test leads must be connected in the correct polarity, otherwise lower out of range values will appear. Use the Positive Lead for the COOL control circuit and the Negative Lead for the HEAT control circuit. If the resistance is measured with the seat still warm or cool, the resistance values will vary even if the system was powered up for just a few seconds. The TED must be allowed to stabilize to room temperature prior to a measurement. The following conditions will change the resistance to out of range values:
* The test leads are incorrectly connected
* Air blowing across the TED.
* Measuring the resistance at other than room temperature of 70°F.
* Holding the TED portion of the heated and cool ventilation module in your hand.
In hotter or colder climates where room temperature conditions of 70°F (21°C) may be unattainable, resistance values may read above the specified range. Use a heat gun or a blower to warm or cool the TED while measuring the resistance. The resistance values should slowly lower toward the specified range.
Test for 0.9-10.0 ohms of resistance between the heat control circuit terminal 1 and the cool control circuit terminal 3.
• If the resistance is not within the specified range, replace the ventilation heat and cool module.
Important: The test leads must be connected in the correct polarity, otherwise higher out of range values will appear. Use the Positive Lead for the supply voltage circuit and the Negative Lead for the ground circuit.
3. Test for 6-9K ohms of resistance between blower motor supply voltage circuit terminal 2 and the low reference circuit terminal 4.
• If the resistance is not within the specified range, replace the ventilation heat and cool module.
Important: The test leads need to be connected in the correct polarity, otherwise higher out of range values will appear. Use the Positive Lead for the speed control circuit and the Negative Lead for the ground circuit.
4. Test for 290-420K ohms of resistance between blower motor speed control circuit terminal 7 and the low reference circuit terminal 4.
• If the resistance is not within the specified range, replace the ventilation heat and cool module.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
* Heated and Cooled Seat Switch Replacement
* Seat Back Ventilation Heat and Cool Blower Replacement
* Seat Cushion Ventilation Heat and Cool Blower Replacement
* Control Module References for CCS module and MSM replacement, setup, and programming Programming and Relearning Verification Tests