UK Triker Forums

Hi everyone MrHyde here. I'm new to this forum and don't have a trike of my own, but I'm trying to help a friend with his. I don't have a lot of information available but I'll give you all I have. It's a 2010 (I think) Boom Mustang Thunderbird. It's powered with a Ford Duratec 4 cyl engine with manual trans. I'm trying to locate the brake light switch but I haven't been successful. I found a level sensor switch in the master cyl. reservoir and also an hydraulic switch on the master cylinder, but it's clear it doesn't control the brake lights. I've followed the brake pedal linkage and the brake lines as well as I could without any major disassembly and can't find a switch anywhere.

If anyone has had experience and knows the location of the brake light switch I'd be grateful if they would share that information. Thanks in advance.

Ahhh, I see you are looking for the location

Try and borrow a tone generator, and put it on one end of the brake light wire. You could then trace the tone, and hopefully end up at the switch.
For example - https://cpc.farnell.com/tenma/72-2665/n ... dp/IN07348

MrHyde wrote: ↑Wed May 15, 2019 10:04 pm and also an hydraulic switch on the master cylinder, but it's clear it doesn't control the brake lights.

Query - clear how? Not knowing Boom trikes, i'm assuming a single circuit system to front? and rear brakes? It will either have a mechanical switch connected to the brake pedal or lever (if it has separate front bike style controls) or a hydraulic switch like below usually replacing a brake line banjo - does what you've found look like this? If it does, then i'd suspect a u/s switch or a wiring fault?

On my VW engined Boom it uses a hydraulic brake switch on the master cylinder, when it went wrong it took some tracking down, however in the end i bought a new one and swopped it out and the brake lights worked.

Kawazuki wrote: ↑Thu May 16, 2019 8:12 am

MrHyde wrote: ↑Wed May 15, 2019 10:04 pm and also an hydraulic switch on the master cylinder, but it's clear it doesn't control the brake lights.

Query - clear how? Not knowing Boom trikes, i'm assuming a single circuit system to front? and rear brakes? It will either have a mechanical switch connected to the brake pedal or lever (if it has separate front bike style controls) or a hydraulic switch like below usually replacing a brake line banjo - does what you've found look like this? BL992-31C Product.jpg

If it does, then i'd suspect a u/s switch or a wiring fault?

I should have given more information perhaps. The hydraulic switch on the master cylinder is plumbed into the front brake circuit. With the wires disconnected from this switch the brake lights will still work. I suspect this switch is a BOO (brake on / off) switch for the engine control computer. There is no mechanical switch on the brake pedal, lever or linkage.

That's a weird set-up - why would the ecu need to know when you are braking? If the brake lights still light - using the handlebar lever or the footbrake? - there MUST be another switch somewhere - Bike brake lights are wired this way ie. switched in parallel so whether front or rear brakes applied together or independently, the light comes on.

Automotive systems have been using a BOO switch to let the ECU know whether or not the brakes are on since the early 90s. Not anything new in my world.

Boom literature says it is to limit engine power when braking. Maybe concerned about a stuck throttle condition ??

Have you had a look under the dummy tank as there is a solenoid etc related to the front braking under it, so what your looking for may be there

Thanks kayjay, I don't have the trike in my shop right now but that was where I was headed next. After checking everything else it seems like the only place it could be.

I have the same problem, the switch is located under / in the dummy tank on the right hand side. Mine is not letting the start button power up to start. My question is- can a brake light switch be adjusted or do I have to get a new one. Regards Bill.