I have an 84 cougar, it was once a turbo, but bought it without the motor and trans. It now has 302 and an aod. The signals work fine when the car is sitting still (in park, drive or reverse) at an idle or with some engine revs, but when I take it for a test run I can hear the fuse blow (usually within 10 - 30 seconds) even though the signals are not being used. I've tried new signal switch, flasher, better body ground and the grounds at the light harnesses. The reverse lights are not hooked up and thought maybe the hot wire could be grounding out but can't find it. Any ideas?
I'd look for a pinched or chaffed harness in or around the steering column and pedals
I didn't find the problem but I did get around it. I used a spade terminal and put it in the hot side of the fuse and then put in an inline fuse holder followed by a flasher and found the feed wire to the signal switch, hooked it up and it worked. So you were probably right about the chaffed wire, it must be bad between the original fuse and flasher unit somewhere. I hope as long as I'm not feeding power through that wire it does not cause any further problems.