[Mgs] Turn signal flasher

PaulHunt73 paulhunt73 at virginmedia.com
Sat Apr 16 02:24:45 MDT 2022

The original 2-wire flasher units do not ground, they operate in series 
with the lamps.  The early 3-wire units don't ground either, the third 
terminal is for the dash tell-tales.  Only the later OEM 3-wire 
electronic units have a ground wire.  The apparent benefit of those 
3-wire is that they don't slow down as system voltage falls and 
connection resistances rise, which is why many fit them.  However both 
those problems are contributing to dim lamps, which is still the case 
with the 3-pin flasher units, fix the faults instead.

But this is a mine-field, many people confuse them with hazard flashers 
which are also 2-wire and 3-wire.  Hazard flashers will appear to work 
when used as a turn signal flasher but there is a delay after operating 
the switch before the lamps light, which is ... a hazard, as is not 
warning you when a corner bulb has failed, which both the original 2-pin 
and the later electronic 3-pin do. LED flasher lamps fall into the same 

There are also modern cube-type 'universal' flasher units (they re not 
'digital' any more than the others are) and most of those should be 
avoided, some so-called LED flasher units need at least one filament 
bulb to work.


On 15/04/2022 22:08, Max Heim wrote:

They are interchangeable either way, with a little effort. The 2-wire 
ones ground through the housing — the 3-wire ones have a ground wire, 
that can easily be added if not present.

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