The connector that goes to the Sender is a basic Spade lug... just unplug it from the sender and touch it to the engine block to see if the Temp gauge reads a warming up engine. No cutting or mangling of the sender.

If the gauge on the dash moves, then a good chance the sender is bad.

You can clip a meter on the sender ( where the wire attaches) and the other lead of the meter to the block of the engine, start the car and see if the resistance changes as the Engine heats up. That's all this sender is, A thermal resistor.
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'75 Jeep CJ5 345Hp ChevyPwrd, two motorcycles, '85 Pickup: The '89 Volvo is the newest vehicle I own. it wasn't Volvos safety , it was Longevity that sold me http://home.no.net/ebrox/Tony's%20cars.htm