Brake light works with front brake, not rear brake?

dlim

Joined
Apr 4, 2022
Messages
97
Location
Seattle, Washington
Bike
2007 ST1300
The brake light activates when I use the front brake, but when I use the rear brake it does NOT light up!

Any good guesses on what may be causing this to save me some time troubleshooting PLEASE...

Thanks in advance!
 
Check the rear brake bulb?
Check the brake switch (pedal depresses plunger I think) behind the brake pedal?
Fuse under the left side cover?
I'm not used to having to think, this far from lunch time...
 
If the front switch works the light, then the problem must be at the rear switch.

Added: The two switches are wired in parallel, so they share the same fuse, etc.

Either the switch is bad, it's not being activated, or one of the wires is disconnected.

Start by looking at the pedal movement and whether it's pulling on the spring.

Added: Check the switch itself by pulling directly on its plunger rod.
 
Last edited:
If the brake lights illuminate when the the front brake lever is pulled this means that the bulbs and fuses are all good. It also means that all of the wiring is good with the exception of the section of wiring between the rear brake pedal light switch and the brake lamp harness.

The simplest test is to unplug the switch at the brake pedal and jump the wires to see if the brake light illuminates. If it does, everything after the switch is good and the problem is either a defective switch or one that is not being activated by the mechanism. If it doesn't, there is a problem with the wiring between the switch and where those wires join the main brake lamp wiring harness.
 
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