A couple of weeks ago my parking lights began coming on when I applied the brakes. The brake lights were working fine though. This week my brake lights became stuck on permanently.

There are two switches attached to my brake pedal. Yesterday I replaced one of them (the lower one that is black, 3M5T-1348-AB). Replacing the switch has remedied the problem of the brake lights being stuck on but not the problem of the parking lights coming on with brake lights. And now I have a new problem. When I switch on my parking lights they flicker. 

Has anyone any ideas what the problem may be please? I have ordered the other switch (the upper one which is blue 3M5T-98572-AB) but it will only arrive next week and I don't hold out much hope of it fixing the problems.

Try new bulbs

Thank you. I haven't tried new bulbs but I did check them and all the connectors. I even disconnected the rear light clusters but the sidelights still come on with the brakes.

I think I have sorted it. I hadn't checked the bulbs after changing the switch. If I remove the driver's side brake and tail light bulb the problems go away. I'm off to Halfords later for a bulb.

The brake element in the dual element bulb snaps and falls onto the back light element. When you press the brake pedal current flows through the brake light element and through the back light element illuminating them both at the same time. Because the back light is wired to the front parking light that comes on as well. 

Thank you. New bulb fitted, problem solved.