If the test lamp does not illuminate, you should test the signal circuit for a short to voltage or open/high resistance. If the circuit tests normal, you should replace the MSM. If the test lamp remains ON with the switch in the OFF position, you need to test the signal circuit for a short to ground. If the circuit tests normal, you should replace the MSM. If the resistance is measured with the seat still warm or cool, the resistance values will vary. At 20, the nominal resistance value is 1200 Ohms±5 percent. For warmer or cooler 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.