if you would are wored you can use OHM's Law the first step is it find the resistance of the horm DMM or if you you shold be able to find specs on a shop manule that will give you the ma pull of the horn. if you do not have a DMM but can find the amoeres pull simply use this formula to find resistand R = 6/I (I= Current in AMPS and you are using 6 for 6 volts) then wen you have the Resistance cunect a res. with the same R value in seareas. then your hore will get just 6V and the corect I to it.
