GMC Jimmy gauge & ignition key problem

I just purchased a 1997 Jimmy and found a couple of problems. The Temp gauge does not work. The fuel gauge reads erraticly, It goes all the way up & down while engine is running. The Ignition key wont turn to the lock position without pressing the manual release under the column. Are all these problems related? Maybe a BCM or PCM? Thanks, dru

do you have an automatic or manual transmission?

Automatic

It not a BCM/PCM problem. For your temp. gauge you need to replace the temp. switch. As for the fuel gauge, these vehicles were known for having bad fuel sending units. There are a couple test that can be done to isolate the problem.
The ignition switch is probably worn or the it could even be the rack that is worn. That you will have to get it diagnosed by a tech. Good Luck.