Percolation? Heat soak? Don't drive during summer??

Try not to use electrical tape to wrap the harness. There's a wrap tape which has no adhesive that makes far less mess when you remove it, or when it gets heated. You pull it tight and it also shrinks slightly with exposure to heat. Works great! The ends are typically affixed with adhesive tape though to prevent unraveling. I like to use the fabric stuff though, looks like hockey tape. It holds better to itself and doesn't become gooey or slimy over time.

You gotta link?