Typically, a horn or light relay is used to alow a smaller wire drawing lower current to be used to run to the switch. Large power wires run from the fuse box/battery to the relay and the accessory and thinner wires run to the switch. This provides a shorter path for the higher current wire. Perhaps when you took out the old relay, the resulting wires are not large enough to carry the current for the horns and are causing a voltage drop? Just an armchair diagnosis.
|