Help needed with constant brake light on.

Hi all my xr has developed a strange fault, the brake light bulb blow yesterday so i replaced it and checked it and all was good, but when i got the bike back out today its now got a constantly turned on brake light(both filaments on) unless i turn the lights off at the switch and then the brake light wont work at all from the front or the rear brake   

anybody got any idea's what it could be and were to start looking as i am terrible with electrics  

Switch on the brake pedel bad.

Take a multimeter, disconnect the brake pedal switch, test the switch.

AURORA wrote:Switch on the brake pedel bad.

Take a multimeter, disconnect the brake pedal switch, test the switch.

Thanks AURORA i will check that out today   

Of course use ohm setting first for connectivity circuit test.

AURORA wrote:Of course use ohm setting first for connectivity circuit test.

Will do AURORA, just need to get my hands on a multimeter now  

Simple enough, your ground seems to be open-circuit - that's disconnected/broken, so fix that and it'll work again   

Bring it to me when you have time , i will look at it mate .

Mad Frosty wrote:Bring it to me when you have time , i will look at it mate .

cheers for the offer frosty but the problem is sorted, even had time to give the bike a good clean down afterwards   

kirky wrote:problem is sorted

Watwazzit?

BuRP wrote:

kirky wrote:problem is sorted

Watwazzit?

I'm not a 100% sure to tell the truth   , i just cleaned all the connections and insulated everything that i could see and tested it and it now works   

so thank you to everybody for the help and advice   

Hawthorne effect

well i thought i had fixed it but two bulbs later after a 5 minute ride would say otherwise   

1st bulb


2nd bulb


first one blow when i kicked the bike into life and the second one died shortly afterwards  

Sounds like your regulator isn't doing its job.

I have to agree with ooeddym it seems that you need a new regulator , we need to measure the voltage when your bike is running to see if its within the spec .

ooeddym wrote:Sounds like your regulator isn't doing its job.

one regulator replaced   



luckily i had a spare one that i tested a while ago but i'm all out of bulbs so i will have to wait till the morning.

fingers crossed it is just that 

13,5 -14,5 volts at 4500 rpm's .

Mad Frosty wrote:13,5 -14,5 volts at 4500 rpm's  .

cheers frosty, if it blows the next bulb tomorrow and i cant get my hands on a multimeter i might take you up on your offer at some point  

Andy that is the regulator/rectifier on your picture , you need to check the ac regulator ( the finned aluminium thingy attached to the top of your airbox ) .

Mad Frosty wrote:Andy that is the regulator/rectifier on your picture , you need to check the ac regulator ( the finned aluminium thingy attached to the top of your airbox ) .

will do frosty, i'll try tomorrow and thanks   

Is that a DC regulator in the picture? My bike stock only had the aluminum finned AC version bolted under the seat.

yes thats a dc reg in the pic only comes stock on the euro and aus versions of the xrr , the black thing nxt to it is a capacitor

Yip, only 1 reg mounted, either AC or DC... not 2 of them.
I think a bulb on a vibrator cannot last, you're better off mounting the LED kit (brake & tail).
But, inferior quality bulbs often last as long (lol, short I mean) as you indicate, best is to buy Osram or Philips globes only.

kirky wrote:

ooeddym wrote:Sounds like your regulator isn't doing its job.

one regulator replaced   



luckily i had a spare one that i tested a while ago but i'm all out of bulbs so i will have to wait till the morning.

fingers crossed it is just that 

Which two wires are the 12VDC + & - coming out of the reg pictured here?

The black wire that dont go to the cap or that lil black tube ...green is neg

i have just found a nice LED kit on ebay but i don't dare buy it till i have this problem sort.

sorry about the quality of the picture, here's a slightly better one Zoro