headlights go out after about 10 minutes

I have a 92 240..recently the headlights have been going out after
about 10 minutes of driving,,,i can keep the hi beams on by holding the
switch in...and if I turn on or off the headlite switch the lites
usually come back on...my question? is it the relay or the switcn

 

First thing to check is the fusebox for corrosion, then the bulb failure
sensor for cracked solder joints, then look into the switch and then the
relay under the hood.

 

There is an on-off relay that turns the headlights off with the ignition
under the dash. I'd say that's most likely your problem as there are no
fuses at all anywhere in the headlight circuit, and the function that
turns the high beams on by holding the switch bypasses that relay.
Don't confuse this relay with the hi-lo relay that is mounted on the
inner fender under the hood.

Of course, cleaning your fusebox is always a good idea on a 240. I
cleaned mine yearly, whether it needed it or not, back in the days when
I had 240s. After a 10 minute drive, any fuses that are any more than
slightly warm to the touch need work, but be careful, they can often be
hot enough to burn your fingers.

--
Mike F.
Thornhill (near Toronto), Ont.

Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)