My 2000 Ford Taurus won't shift into fourth gear is it ok on a 700 mile round trip drive?

I have a 2000 ford Taurus and it doesn't shift into fourth gear anymore. Its been that way for 2 years. It runs fine just doesn't shift into fourth gear and the transmission light does come on after a while of driving it. I was wondering if it would be ok to take it on a 700 mile round trip drive? I know its not good for it I just need to know if I'm going to be stranded on the highway somewhere because my trans went out.

Well I haven't had the money to even think about getting it checked out. Like I said the car runs great just won't shift into fourth gear. And yes it is in the correct driving range and no overdrive switch. Just stopped shifting one day. Thinking about taking it on a drive was wondering if it was going to break down on me.

Your transmission has been mal-functioning for 2 years and you haven't had it checked?

I sure can't diagnose it here… Besides mechanical issues, it's electronically controlled… So there may be many causes for the missing shift… Could be as simple as a blown fuse. (I'm assuming you have it in the correct driving range and there isn't a separate Overdrive switch that is in the wrong position).

Whatever… It isn't going into overdrive… You're increasing your fuel consumption and wear on the engine.

Most of all - you're developing excess heat in the transmission by driving around in 3rd gear… That could be a fatal condition on a long, hi-speed drive.