Can someone tell me how to turn the light on? Does this have batteries that need to be replaced.

TTT???

Yes, there is a 9 volt ni-cad battery in the back that needs to be replaced. To get the backlight to turn on you need to hold the white mode button and the max button simultaneosly for two seconds. You should be able to get the instructions from Digatron (509 467 3128) or exhaust gas thchnologies. If you can't, let me know and I will send you a copy in the mail. Good luck! Jay