Hi tabetha the horn and the heater are on different fuses ,but on useing the test wire the blower works on all three speeds so i know its not the blower, just tested the feed to the horn thats only reading 5/6 volts as well ??? am i right in thinking that there must be a break in the wire or has the fuse box gone???? i know the mrk 5 fuse boxs the solder drys out then thats when you start getting the props.