After 21 years the motorized antenna on my 86 coupe finally failed. I came out of the store 1 day and the antenna was in the up position and the motor was continually running with the ignitiation switch in the off position.
I ordered a replacement antenna assemble from one of the after market folks along with a recomemded replacement relay. After about 1 hr this antenna assemblefailed as well. after removing the antenna assemble and disassembling it I found that the motor was melted to the housing. Thinking that the relay had in some way allowed more current to the motor than neccassary I checked the recommended antenna relayand found that the part number didn't match to factory model.
Thinking that this was the problem I ordered a replacement antenna relay from the local dealership and ordered another antenna assemble from the same after market folks.
About 2 weeks after installing the new antenna assemble and relay, I was parking my car when the radio, antenna and interoir lights quite working. After looking at the fuses I found that the 15 amp fuse that provides power to these items was blown. I replaced the fuse which worked for about 5 minutes and failed again.
Knowing that the last itemI had replaced was the antenna assemble and relayI disconnected the relay and haven't had anymore problems.
Since the antenna assembles are expensive I don't want to intall a second new unit until I find out what the issue is.
Has anyone else experienced this same problem?

 

Welcome to CF!
I'm moving your post to the C4 forum,
where it will get more attention.