[Tim Cole]

Congratulations on your purchase of the 77 Thunderbird. Hope you enjoy it and enjoy working on it.
Per your question, the cruise control is not part of or connected to the other problems. It has to be dealt with by itself; removed and rebuilt.

The other issues might related to a burned out fuse. Check your fuses first--under the dash by the dimmer foot switch. You also should have a handbook in the glove compartment for your 77. It will include a diagram indicating which fuses control your dash lights, etc.

If all fuses are good--and check them in bright lights--remove the dash cluster. On the back of the dash cluster in a printed circuit. The printed circuit can be removed (carefully due to its make-up and age) and the different circuits lines cleaned carefully with rubbing alcohol and a Q tip. Remove each light and clean the contact points with fine sandpaper. Check the contact points or leads for on the fuel and temp gauges.

If cleaning does not solve the problem, come back here and I'll give you step 2 to track down the problems: might be that the temperature sending unit under the hood might need to be replaced (easy removal) on the motor; the fuel sending unit inside the gas tank might be bad and in need of replacement. If bad, it will not send a signal to your dash gauge. But take the first steps and see what you come up with.

Don't worry. You'll get to the root of the problems. Have fun!
All the best to you. Tim