2017 T100 Brake Switches Problem

My Bonneville T100 just failed its latest MOT due to the rear brake switch not working. Buying a new switch didn't fix the problem and investigating further I found the front switch although appearing to work, was actually not working properly either. My first question is, "Does a dodgy front switch affect the feed to the rear switch?".

I tested the voltage at the rear switch connector at 9.5V so it seems something is not quite right here. Also, on taking the front switch gear apart I noticed the micro switch seems to work in the reverse direction i.e. the brake light comes on when the switch is out. Pressing the switch in switches off the brake light and then releasing it the brake light struggles to come on which indicates a bad connection in the switch.

The other bugger is the front micro switch is not listed as a separate part, you have to buy the whole switch cube which seems bloody ridiculous and expensive at £144. I wouldn't mind buying the whole new switch cube though if it guaranteed to fix the problem with the rear switch. I just don't want to shell out for it to find the problem persists.

I have tried spraying the front switch to clean the contacts but to no avail. Any help or suggestions appreciated.

 

I managed to fix the problem in the end. My first instinct was correct as the front switch does indeed control the supply to the rear switch. In a non-braking state voltage is suplied via the front switch to the rear so that if you just presed the rear brake the light comes on. If you pull the front brake the current is routed directly to the brake light which means if you apply both brakes simultaneously, current is only flowing via the front switch, not both.

Another thing that might help anyone out if they are experiencing brake light problems is that the switches operate in a reverse direction i. e. In the non-braking state both switches are pushed shut and open when the level is used.