Jasen Betts wrote in a message to George White:

 JB> Hi George.


 GW> That would be better as a technical explanation. In fact older
 GW> vehicle flasher units were capacitor/relay oscilators

 JB> the really old ones were bimetalic.

I thought that most of them still were!  In fact,  at the auto parts store
you can get an "electronic" one but it costs a bit more --
they're sold in those cases where a vehicle is towing or otherwise has more
lights than the ordinary one will deal with.

 JB> those capacitor ones don't work to well when they get hot... (I've 
 JB> not compared a bimetalic one's performance) 

 GW> Time has dimmed the memory of how it was done but it used a
 GW> electrolytic capacitor and relied on a controlled difference between
 GW> the pull in and drop out voltages of the relay.

 JB> the ones I've dissasembled used a relay with two windings. and had
 JB> the current flow one way through the cap and windinh with the
 JB> contacts closed and the opposite direction with them open.

The one I've got disassembled on my desk here has three connection points, 
with the bimetallic strip between two of them and contact points for the
load between two of them.

Maybe it's not a flasher?  I seem to remember some vehicles I owned having
a similarly packaged device in the dashboard that they referred to as an
"instrument voltage regulator",  and most flashers that I've
encountered in recent years had only two pins,  not three.

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