My Tahoe has an under-dash electronic trailer brake controller. If I gently touch the brake pedal and let off, the LED on the brake controller will stay lit as if the brake light switch is sticking. Now you would expect the vehicle brakes lights to be on while this situation is occuring but they are not. You can then give the brake pedal a tap and the brake controller LED goes off. How can this be?

 

Gees, this is a wild guess...

Insufficient 'return' pressure in/on the Brake Controller actuator.
Maybe a brief squirt of some light lube will make it return sufficiently.
(is your brake pedal returning completely ?, try pulling up on it with your toe)

 

I would concur with SWHouston assessment...

 

Thank you guys for the input. I hope that's the simple fix. I should have already tried that. And I will as soon as my wife gets home with the car. But are there two separate switches on the brake pedal, one for brake lights and one for trailer? I don't why else the LED would be on for the brake controller but the vehicle brake lights are not on.

 

Yes, two switches.

A mal-adjustment. We think the Brake Petal is not moving back (toward you) sufficiently enough to move off the Controller Switch, but well enough to not cause your Vehicle Brake Lights to light.

There may be a Screw/Bolt adjustment to relieve the pressure on the Controller Switch.

Understand, that there is "balance" in the application/pressure on the two.
If you feel uncomfortable in "coordinating" these two, you don't have to go to a Dealer.
Any qualified Trailer Shop, will be quite familiar with those adjustments, and will probably cost much less.

You may just add a Spring to pull your Vehicle Break Petal fully back.