You know it would depend on my mood. I've not ever had to fool with them but imagine I'd most prefer to put the car on a lift and go at them from the bottom without removing the wheel or the liner. Yours might have more "stuff" under there as the US cars are different in ways from the euro type that mine is. The following is how I'd chase my girly sound on my euro car. remove the wire from each one and clean the contacts and reinstall the wires. There are 2 horns. Toot. No change? reverse the wires to the horn, toot again. I'd expect change. From there you should be able to isolate the offending unit while at the same time verifying there is juice going to the unit proper thru the wires. Good luck. chris