Some key functions of a thermocouple in a cotton picker include:

1. Monitoring engine temperature: Thermocouples often used to measure the temperature of the engine block, cylinder head, or other components to ensure they are operating within safe temperature ranges. This information can help prevent overheating, which can lead to engine damage or failure.

2. Monitoring exhaust temperature: Thermocouples can also be used to measure the temperature of the exhaust gases as they exit the engine, helping to optimize combustion efficiency and diagnose potential issues with the engine or exhaust system.

3. Providing temperature data for diagnostics: By measuring temperature at various points in the cotton picker, thermocouples can provide valuable data for diagnosing potential problems, optimizing performance, and ensuring the machine is operating efficiently.