Suburban 4WD V8-5.3L (2008)
1. Ignition ON, verify that the HVAC module driver and passenger heated seat switch parameters display Active while any of the heated cooled seat
switches are pressed.
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If either of the switch parameters are continuously Active or Inactive while any of the headed cooled seat switches are pressed, replace the
HVAC control module.
2. Verify that the MSM driver and passenger seat HVC mode and level parameters are displayed correctly as the heated cooled seat switches are
activated through all of the operating modes.
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If the MSM parameters are not displayed correctly replace the MSM.
3. If the circuits test normal replace the HVAC control module.
Driver and Passenger Heated/Cool Seats Circuit Test
1. Ignition OFF, disconnect the X1 harness connector at the CCSM.
2. Ignition OFF, test for less than 5 ohms of resistance between the ground circuit terminal M and ground.
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If greater than 5 ohms, test the ground circuit for an open/high resistance.
3. Verify that a test lamp illuminates between the B+ circuit terminal E and ground.
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If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
4. Ignition OFF, disconnect the X2 harness connector at the CCSM.
5. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 1 and ground.
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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.
6. If all circuits test normal, replace the CCS module.
Driver Heated/Cool Seat Circuit Test
1. Ignition OFF, disconnect the X1, X2, X3 harness connectors at the CCSM.
2. Connect a test lamp between the heated/cooled seat mode signal circuit terminal 14 X3 and battery voltage.
3. 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.
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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.
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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.
4. Test for 300 ohms to 18K ohms of resistance between the following temperature sensor signal and low reference circuits.
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Connector X2 seat cushion temperature sensor signal circuit terminal 7 and low reference circuit terminal 8.
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Connector X2 seat back temperature sensor signal circuit terminal 9 and low reference circuit terminal 10.
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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 heat/cool seat ventilation blower.
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If the resistance measures less than the specified value, test or replace the appropriate heat/cool seat ventilation blower.
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:
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The test leads are incorrectly connected.
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Air blowing across the TED.
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Measuring the resistance at other than room temperature of 70°F (21°C).
