Quote from John Spina: "The purpose of the relay is to allow the coolant fan to run for five to ten minutes AFTER the car is shut off ONLY if the coolant temperature rises above 226 degrees F.
This helps the engine cool down, when you leave the vehicle, under extreme conditions such as use of the air conditioner in heavy traffic during very hot days."
He goes on to say: "Personally, I would disconnect this relay & leave it out of the car completely. Since we all use 160 degree thermostats and most of us have good radiators, the effectiveness of this relay is minimal and not worth the outside chance that it might kill your battery or adversely affect your electrical system when it fails."
Mine has been unplugged for over a year now. HTH
I copied the above from a previous post. I didn't know if you were aware of it or not. I can't help you on the circuitry of the relay itself though. If you do decide to replace it, most TR vendors stock it, & fairly cheap as I recall. HTH