BONNIE MAINTENANCE
Corroded, Fried, Dead Bonneville T100 Ignition Switch

My bike is approximately four months old. Therefore, the ignition switch has been in use for four months. Yeah, I was annoyed with the position that Triumph placed it. Sure, isn’t everyone with sense? So, three months ago, I moved the ignition switch to the downtube using Joker Machine‘s Relocater Bracket (see this mod and this update).

For three months, I’ve been enjoying easy access to the ignition switch. Unfortunately, that came to an abrupt halt last week. After work, the bike wouldn’t start. I assumed that it was a dead battery since the temperature was in the teens. By luck, I jiggled the key at one point and the electrics fired up. Okay…

The next morning, the bike started up fine and ran fine. After work, it also started but then quickly cut out 1/4 mile into the journey and it continued to continuously (redundancy?) cut in and out. I noticed that any slight turn of the handlebar (thus flexing the ignition wires) would cause a disruption. At this point it was obvious that I had a loose connection. I took a wadded up paper towel and seated it to force the connection to stay connected. Fingers crossed and I made it home.

Once home, I grabbed my tools and pulled off the Joker Machine bracket and removed the ignition switch. From here, it was a pair of Philips screws that needed to be removed to access the inside of the switch.

Back of an ignition switch for a Triumph Bonneville T100. Bonnie Cafe.
Back of an ignition switch for a Triumph Bonneville T100. Bonnie Cafe.

With the Philips screws undone from the ignition switch assembly, the black cap can be removed to expose the contact plate.

Back of an ignition switch for a Triumph Bonneville T100. Bonnie Cafe.
Back of an ignition switch for a Triumph Bonneville T100. Bonnie Cafe.

If you look closely at the above photo, you can see how the wire leading to one of the “ON” contacts has separated. In the below photo showing the front of the contact plate, you can see how the contact has completely disappeared. There is no copper nub contact. (Did it melt away? Fall out?)

Inside view of the contact plate of an ignition switch for a Triumph Bonneville T100. Bonnie Cafe.
Inside view of the contact plate of an ignition switch for a Triumph Bonneville T100. Notice the burned out contact. Bonnie Cafe.

The inside of the switch assembly was full of gunk. I was amazed. Looking at the assembly, it’s easy to see why. There is a gaping hole where the leads run and this allows for all kinds of dirt, water, and gunk to come in and collect. Furthermore, there is no drainage so everything just sits in there and ferments. (Full disclosure: I have ridden the bike in all sorts of inclement weather. If you don’t, you probably won’t suffer the same consequences.)

Inside view of an ignition switch for a Triumph Bonneville T100. Notice the gunk? Mind you, I cleaned out about half the gunk before stopping to take this picture. Bonnie Cafe.
Inside view of an ignition switch for a Triumph Bonneville T100. Notice the gunk? Bonnie Cafe.
The hole which allows the leads to come into the an ignition switch assembly for a Triumph Bonneville T100 also lets in dirt and water. Bonnie Cafe.
The hole which allows the leads to come into the an ignition switch assembly for a Triumph Bonneville T100 also lets in dirt and water. Bonnie Cafe.

So, what are my options?
1. Buy a new OEM assembly.
2. Buy a used assembly.
3. Fabricate some sort of copper nub.
4. Buy a third party ignition switch.

The easiest would probably be #2 and pull the contact plate out of it to replace mine, but after a lot of googling and reading forums at triumphrat.net, I opted for #4. I ordered the motogadget m-lock. It is an RFID keyless ignition switch. It’s coming from Germany so it’ll take a few weeks to arrive. I will keep you posted. In the meantime, I’ve hot-wired the bike in order to ride. (I’m carrying the ignition switch with me in case I get pulled over by the cops. :) )

7 Comments

  1. I wired up the m-lock on my ’13 Bonnie it’s alot of fun. Same with the m-unit and m-switches, except that was alot of work. Thanks for the TEC exhaust review I’m ordering mine soon! Can’t wait.

  2. Just experienced this myself and in the process of doing a repair.

    Interested to read your usual high standard write up and photography of how you get on with the M-Lock.

  3. Found out today that my ignition switch assembly have a copper plate corroded just like the one on your Bonneville. I have a 2012 Bonneville T100. Ignition switch assembly at the manufacturer positioning. I filled the corroded gap with some wire solder. Problem solved for now.

  4. My 15 month old T100 developed the same fault and the ignition switch is in exactly the same place mine was replaced under warranty no questions. I have since stripped it off added some self amalgamating tape and an extra layer of heat shrink too make sure it’s water tight.

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