My check gages light flickers, and the tachometer and speedometer are not working. When this happens, it does not shift properly. Seems like I only have 2nd and 3rd gear. Was an intermittent problem until recently. Have replaced battery cable, cleaned posts, etc. Any advice would be greatly appreciated.

A flickering light can be a misfire. You should still scan for codes to see any are stored.

A misfire can be many things but a good place to start is with cap and rotor, wires and plugs.

You can also search for misfire in this section and find many posts on the subject.

//2000CAYukon

Bad ignition switch can cuse some problems like this--worth taking a look at. Try turning ignition key a fraction more towards the off position, but not off, and see if that changes anything.

I've replaced plugs, wires, rotor, distributor cap. Tach and speedometer still not working. Could transmission be in "safe mode"? Thanks

Are there any codes stored?

//2000CAYukon

Replacing ignition switch cured the problem. Thanks for all assistance

Glad you got it fixed--but it is a strange part to cause those problems!!