Ignition switch wiring queston

Ok so i have my stock wiring loom that i have pretty much fitted and have come to the ignition switch connector. Now a while back i jumped on a new key switch that was a decent price as my old switch would intermittently seize and not turn. Ive just realized the new switch plug is a three pin connector verses the original four pin ( three pin -Brown, Red, Blue , four pin- Brown, Red, Blue, Blue red stripe ) . obviously the plugs are not compatible but.............if i were to get a new plug to match is there a way i can utilize the three wire switch.
Id appreciate and electrically minded brains ideas and thoughts.

 

there is a thread in how to's on fixing the switch, do you still have the original switch? it is real easy .
would also have to know what bike you have

http://www.xj4ever.com/clean and lube the ignition switch.pdf

three wires on my xj550 also same on 650
red comes from main fuse
blue goes to tail light
brown goes back to fuses
got a wiring diagram?

 

you could combine two wires into one connector in a 3 pin socket.
this will put more stress on the wire going from the connector to the switch.
but without knowing what your extra wire is for and its amp needs you may cause your self problems and end up buying a new switch.
you would be better off running a fused wire from your battery
with a switch on it to the "extra" wire.
need a wire diagram to say what your wires do.

 

Similar colour coding on my xj750uk. Red traces back to main fuse, Brown also traces back to fuse block but serves head light and signals
Blue feeds light switch and control panel lamps. Blue /red serves licence plate and parking light .
I also have two red/white wires but these serve battery sensor and cockpit battery warning light.

 

if as suggested by CapnRedbeard it is your tail light and plate light run a wire and switch to it with inline fuse from battery to the connector.
just remember to shut it off.

 

Yep thought it might not be that simple. Ive sourced a four pin switch to save the headaches.
Thanks to everyone for our helpful input.