Hello everyone. My name is Jonathon and I am new to the site. I recently purchased my first Harley. A Beautiful 1989 Sportster 1200. Its pretty custom and the only things left stock on it are is the engie and frame. That being said yesterday I was relocating my tail light from the left side, if sitting on the bike, back up under the fender. I disconnected the old wires Cut them off and re-crimped new wires with spade connectors. When i went to turn the ignition key on my tail light no longer works but the brake light does? also when i woke up this morning my battery was dead. From what I have read it sounds like i have a short to ground somewhere. can anyone else give me some ideas of where to look? Thank you for your time in advance.

 

Let's start with the easiest thing first. Your tail light bulb is probably an 1157 bulb. If so it has 2 filaments, one for the running light and one for the brake light. 1157 bulbs do not always blow both filaments at the same time. Pull out the bulb and check/replace if needed.

Next, check your fuses, especially if you did all this electrical work without disconnecting the battery first. You may have a blown fuse.

Did you just relocate the existing tail light or did you get a new one to replace the old? I'm asking because maybe you hooked up the wires wrong. It's always wise to take pictures and/or label wires before you cut them. Also crimp connectors are famous for making bad connections and pulling apart. You should get in the habit of using solder and heat shrink insulation. Re-check all you crimp connections too be sure. If the wiring has you confused invest in a service manual with wire diagrams. Although a simple test light could show you what wire was energised when the brake is pressed.

As for the dead battery. A short will usually cause a fuse to blow. Once the fuse blows no battery power can be drawn from that circuit. Also, the running and brake light wires are not energised when the bike is off. At least that's how it should be. I'm not sure how old your battery is or when the bike was last run/charged but lead/acid batteries do not hold a charge when stored. Even if you bike sits for just 1 week the battery would drain with no draw from the electronics. It's always a good idea to use a battery tender when the bike will sit 1+ weeks. For right now I would treat your dead battery as a separate unrelated issue and get the light working correctly first.

Good Luck!