--- title: Fixing 1978 Honda CB400A always on neutral light — “decaf” project bike author: tracey pooh type: post date: 2015-08-15 featured: decaf-neutral-light.jpg#top categories: - biking - motorcycles - technical - video tags: - cafe racer - decaf - geek - hack - motorcycle - video - weekend mechanic comment: --- I'm about to sell, with some sadness, my 1978 Honda CB400A "Hondamatic" motorcycle. I have **one last problem** with it -- that's been baffling me for over a year. When I consolidated the speedometer and "idiot lights" to a svelte new cafe racer style chrome LED-based single instrument, I found that its **[neutral light](https://archive.org/details/decaf3) was always on**, no matter what gear. So I finally figured out a clever (if I may say so) way through research to use the "proverbial $7 part" from in-stock Radioshack -- a RELAY switch! Here, I describe and show the problem, step through a bit of the bike's electrical system, and show you how I used a relay to fix the problem. I'll be sad to see you go, little Decaf! The **awesome** video learning **tutorials I used on Youtube** to determine **relays were for me!**: [RELAYS -- How to wire and how they work TUTORIAL !!](https://www.youtube.com/watch?v=F1SGyN6Yp64) [How An Automotive Relay Works and How to Wire 'Em up](https://www.youtube.com/watch?v=UAeKTlieYhw) (thanks, guys!)