I recently have been told by dealership when having oil change/service that the brake lights are non functioning, but upper high mount center brake light is working; so maybe change
the brake light relay ?
Can someone tell me please where to find this replay to replace it ?

 

Bulbs have been checked/replaced?
If they are ok see if you have power and ground at the bulb sockets.

 

I'm pretty sure all the relays for rear-of-vehicle lighting are in the REM.

 

Any idea of how to access the relay - what /where exactly do I need to do to change it ?