I don't think the 'Tour has a drain plug. Disconnect the lower rad hose to drain it.
Did you get the temp gauge fixed? Looking at the testing flow chart isn't a lot of help. It talks about testing the gauge with a variable resistance tester.
The ECT (coolant temp sensor) should have high resistance when cold and low resistance when hot. If the gauge is full hot all the time, that would mean the ECT sensor wire is seeing little or no resistance, or is shorted to ground?
If you need, I can scan in the testing procedure and connector info from my '96 shop manual, I doubt the circuits have changed much for that particular application.
