I seem to remember something about the whole turn signal circuit running
trough the emergency (4-way) switch in the dash. (It would have to, wouldn't
Anyway, over time and without any use, the 4-way switch contacts become
dirty (oxidize) and the signals function erratically. Try "exercising" the
switch (switching it "on" and "off") and see if that helps your problem. I
think I had similar signal problem when I got my '78 MGB. In a severe case,
might disassemble the switch and clean it, or you could just replace it.
PS - if I'm way off base, I'm sure some other listers will correct me!
In a message dated 7/24/2005 8:43:23 PM Eastern Daylight Time,
On my new-to-me '79 MGB tourer, the left (driver) turn signal is driving me
crazy. Sometimes it won't come on, sometimes it comes on at about 1/3 speed,
and sometimes it comes on at 1/3 speed only when the engine is revving
fairly well. The right turn signal works perfectly at all times.
I've checked the lamps and sockets, and the ground wires (all measure 0 ohms
from the socket to body ground). When the left turn signals do work they
burn as brightly as the right ones.
My only thought now is that the switch is bad (a costly item).