HELP PLEASE!

First time on forum account.

My trusted reliable t5 has just started to flash the heads when usuing the turn signals sometimes only - left or right, not so trusted now i say.

I was driving along this evening. As I went to over take some one going slow, I suppose one could say 'Herbbie decided to flash them down in doing so', not at all helpful to anybody on the road. Last thing I need is the gardai to pull me over. No money for road tax since last year sometime oooopppps.

What i can say, is that when you go to pull back the control stick it won't flash the high beams at all, however to put/switch on to high beam normally and to turn off again is ok. I jumped my van over the cold christmas in mayo a few times with another vehicle, perhaps this caused the problem- a quick serge of 24 volts to the E.C.U.? Is it due to a weak battery instead?

Can anyone help?..........bad battery?..... from jump starting?.....common issue? I'll change that battery for a start.