Electronics Forum / Basics / November 2006

I just bought a bunch of 12V relays for some, auto-related uses
(alarms, horns, etc.). Well, I need to know the wiring diagram, or more
simply what wire goes with what.

For instance, I want to add a new horn relay, using a switch, when
grounded, will activate the main, fused 12V lead from the battery to
supply 12V to the horns.

I also want to do a similar thing to my alarm's horn output to use the
alarm's siren and the car's factory horns. The prinicple was the same:
when a switched lead is grounded, it would energize or connect the main
battery12V source to the car's horns. Previouly I bought some cheap
auto-parts store 15-amp
horn relay, which worked as i intended it to for awhile. It still does,
but now doesn't supply enough current for the car's four-note horn
system; only two will sound.

Which colored wire corresponds to what I want to do?