Overdrive not always working

[Zach LaCroix]

Notice going down highway(70-75) transmission was not always shifting into overdrive. Randomly it would shift into over drive and cruise would work again. When it wouldn’t shift into overdrive my cruise will not work. Still shifts like it always has. After sitting for almost a hour it went into over drive and drive at (50-60)like it always has. Stepped on gas to get up a hill and wouldn’t go back into overdrive. Any ideas?? Just started doing this

 

[Eveready]

Check the brake light switch ( don't laugh). Since no experts have chimed in (and I am not one) I do know that on some automatics a blinking brake light from a bad or maladjusted switch will cause the vehicle to drop out of overdrive. Don't ask who spent a year chasing this problem in another vehicle before finding this out.

Ask someone who knows more than I do but it is a start.

 

[RichLo]

also a possiblility, are you sure its actually OD and not the torque converter lockup that its slipping into and out of?