I want to add a switch that will make all four signals to blink at the same time. Is there any easy way do this, or do i need to add some new relays and a completely wire everything from scratch?

All that the indicator switch does is to complete a circuit, the result is that the chosen two lights flash together.
You could install a switch (no relay required) that completes the circuit to both left and right lights.
Bear in mind the flasher unit will need to be strong enough to handle 4 bulbs, you do get heavy duty units. You will be drawing more current than when only two bulbs light up, however your bike should have watts extra in reserve.
It should be easy to find the correct cables from the handle bar indicator switch easily.
Make sure that all connections are waterproof.
Remember that should you bike be under guarentee it is probually better not to tinker just yet.

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To those who say it can't be done - stand aside for those who are already doing it.

thanks JHMM, it's an old africa twin, 94 mod so i am not afraid for the guarentee. I'll give it a shot and se how it works...

Can just imagine the smile on your face when those lights all come on together. Nothing better than a job well done.

__________________
To those who say it can't be done - stand aside for those who are already doing it.

Does your bike have one idiot light for the turn signals or one for left and one for right ? If it has one then there will be inline diodes to stop it back feeding and creating exactly what you want to do. Bridge the wiring before the the diodes with a switch and then you can turn the signals on ( left or right, doesn't matter) and flick the new switch and bingo hazard flashers.

HTH
Pete

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yes it does... and d*m you both now I have an other project to do....

but seriously thank you ...

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2000 Africa Twin
http://two-up-ona-twin.blogspot.com/
Our trip down though Africa and up though the Americas

Harley-Davidsons have this "hazard light" feature fitted as standard, so perhaps you could imitate what they do?

guys, what do you mean when saying "one idiot light"?


edit; should have google'd it first:
Idiot light - Wikipedia, the free encyclopedia

get it now...

Just wanted to clear up what I posted above, the diodes will be located in the dash so just find the turn signals cables before they get to the dash and install a switch so it bridges the cables before the diodes/idiot light.

HTH
Pete

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http://www.curryhunt.co.uk