The Stovebolt Site Forums The Shop Area The Electrical Bay Protecting Tail & Parking Lights Circuits

I’m in the process of a wiring my ‘52 and run across a small issue with making sure all of my circuits are protected. I started to wire the factory headlight switch and realized under that current plan, the tail light/parking lights were not protected as individual circuits. I was going under the assumption that the fuse for the headlights would protect the circuits then realized if either circuit shorts, it would take out my headlights. Then I noticed the even under the factory wiring, the parking lights are only protected by the bi-metallic strip in the original switch. Only the tail lights are protected by the fuse block on the firewall.

The new Speedway 12 circuit fuse box I bought does not have the proper circuits to route thru the block to pick up a fuse, so that is not an option. That attached proposed Electrical Diagram shows how the block is wired.

My first thought (and shown in the diagram) is to attach the parking lights and tail lights to the headlight switch, then utilize the factory fuse block for both circuits, one for the tail lights and the brake fuse for the parking lights (using a lower amperage fuses than the headlight circuit). I didn’t really want to go that route so I could keep the fuses all in one place)

I previously installed two Bosch relays (power from starter, protected by a 40 amp fuse) for my headlights, which I intend to keep so the headlight circuit does not need a high amp fuse (yet to be determined).

Maybe the Stovebolt collective has a better way!

Put two small inline fuse holders at the headlight switch for tail, and brake, it will be the simplest way without a lot of rewiring. You can get late model micro fuses and holders which take up very little room. For the headlights, I would switch it to an auto-reset circuit breaker, that way if you have an issue at night, you could isolate the bad bulb or wire and the other side would remain on without getting under the dash to change out a fuse. All the old headlight switches had breakers built into them, if yours does, there's no need to fuse it.

I'm glad you posted this Phil. It's making me think about my wiring as I'm getting close to completing the job. My light switch does not have a fuse, so it's a good idea to add some to protect my circuits.

That metal strip in the middle is bi-metalic and was designed as a protection device on the original trucks. When it over currents, the strip heats up and breaks the circuit. When it cools in a few seconds it closes the circuit and the cycle repeats.