Q: 2008 Ford Edge turned key on key off key on and displayed check brake system and went off but able to replicate every time

At key on, many dash warning lights will come on momentarily, and then turn off, as a system test as well as bulb check. If the brake warning light goes off immediately, that is normal. If you suspect a fault though, a mechanic can be dispatched to perform a warning light diagnostic, which would include a check for any trouble codes that might have set. The mechanic would also check to see if the light perhaps refers to required maintenance involving the brake pads. Finally, inasmuch as you have referred to a brake system related warning light, one thing you can and should do is check the level of brake fluid to be sure it is above the minimum level in the reservoir. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.