Measure & Testing Furnace Thermocouple - Troubleshooting pilot light flame - test troubleshoot

I am not a HVAC professional. Just documenting how i test my furnace thermocouple. You will need a DMM that can read DC in mV range. You should replace the thermocouple if it drops below 20 mV.

ACE, Lowes, HD, etc... all sell universal thermocouple. Honeywell and GE are the most common brands. 

You can also review and buy them at Amazon: http://goo.gl/9SKSI