2000 Ram 1500. Battery is okay. Posts and connections clean. Dome light will come on but everything goes dead when you try to crank or turn on the lights and then a high tone coming from inside under the steering column followed by clicking like a stopwatch running.

 

Sounds like you have a connection issue, Either the battery terminals or ground. How do you know the battery is "OK"? Was it load tested?

 

Battery condition doesn't really matter here. You have a bad connection somewhere.

 

If you're convinced the battery is good and connections, I check the fuse box and grounds, do a voltage drop from the battery to ground, battery to fuse panel. Have someone help measure battery voltage when you try and crank.

 

My charger says the battery is at about 13 volts and good. I thoroughly cleaned posts and connectors. I even tried jumping it off. I'll check the ground wire. Everyone is ignoring what is going on below the steering column with the beep and then clicking. I'd really like to know what that is.
There is no power getting through to the truck now. No dome light etc. I'll check the voltage drop to ground and see what that is and get back to everybody. My meter just bit the dust for some reason, probably old age, so I'll have to go get another one when the wife gets back from her day out with a friend. Thanks to you and the others for your replies. I'll let you know what I find.

 

Beeping and clicking are probably a low voltage issue. How old is your battery? It may have correct voltage, but can't take any load.