Hi DEFENDERZOOK, mate never, NEVER EVER use a test light on a modern vehicle.
Test lights commonly trigger the air bags and in the USA there have been a number of deaths caused by accidental triggering of the air bags when some has been looking for a wire in and around the dash.
They have have been looking for a live wire using a test light and tested one of the sense wires for the air bag. This has trigged the air bag, hitting the person in the head and breaking their neck.
When working on a vehicle fitted with air bags, ONLY use a digital multi meter.
Your right about starting at the horn. Also check to see if there is two fuses for the horn circuit. On some vehicles there is a fuse covering the horn switch and relay and a second fuse for the power going to the horn.
Cheers
