No relay in the brake light circuit, although there IS the "bulb out" sensor in the circuit.

Stupid thing can CAUSE a bulb out.

More likely is corroded 'n cruddy contacts in the socket and/or on the bulb.

I fought an intermittent brake light in my '90 240..... Come to find that one of the tabs was broken off the black plastic socket assembly thingy. It was held in (sorta) by only two tabs, so was leaning about 12 degrees south. Sometimes it worked, sometimes it didn't.

So I grabbed a good used socket from a carcass in the side yard ---- voila, good lights again.


--
Don Foster (near Cape Cod, MA)