Our Caprice 5.7L temp gauge is not working. At start-up, the needle quickly passes from cold to hot and back to cold. The cabin has sufficient heat. It has 189k miles and runs well with no other issues. In the past, I have changed both the temperature sending on the water pump unit and the temperature gauge sensor on the passenger side head. And I also have had the electrical connector by the head/exhaust wrapped in a heat shield. That connector looks brand new still. So this is all I've had to do to get the gauge working again, but not now. I know that the temp gauge connector has only one wire. I thank you all for letting me know where there are common wire breaks or something else that I am missing.