I bought my car brand new and when the warranty ran out, I've had some problems.

When I move the gear lever past "R" the Overdrive turns off(light comes on). I have to manually turn it back on. Has anyone had problems like this. What can I do to fix it?

 

I'm guessing the momentary switch in the shift lever is bad. You'll likely
need to take it apart and either clean it or replace it. It could be a short
in the wire leading to the switch as well.

 

And another thing. It happens more often when the weather is hot. Does that make a difference?

 

metal expands when it is hot, again either the wire or the switch is bad.