R1100GS brake and tail light bulb voltage problem?

[gog]

MOT tomorrow and final checks show neither my brake or tail light are working. The bulb has one broken filament visually.

Measuring voltage the brake connector shows 12v when brake applied but the tail light only measures 0.2v. It drops to 0v when the lights are switched off, so it's doing something, but concerned about the low voltage. Surely this should be 12v when lights are on?

I've put the bike away now but dawns on me that i measured with engine off. I assume the tail light should come on with headlight regardless...

 

[gog]

new bulb confirms no tail light. brake now working. looks like i'm hunting a broken wire

 

[DrFarkoff]

Grey wire with Black trace Graham is the positive

Brown is Ground or Negative

Check for corroded bulb holder as well

 

[gog]

cheers jay aye i'll get the meter out tmro. the holder looks perfectly good, not a spot of corrosion. had a wiggle of the wires but nothing. good a time as any to remove the flaking old sheathing and re-wrap it all anyway.

 

[DrFarkoff]

No to a Meter they give false readings

Use a bulb whatever way you do it a 21 watt bulb will glow bright at 12 volts and dim at 6 volts

Meters give spurious readings

Better still you want a Sealey PPX or a PP2 Great bit of kit you can "inject" positive or Ground an item out just by rocking a switch

 

[gog]

ppx looks useful, cheers, i've ordered one. will come in handy for other stuff i've got to do this year too

 

[gog]

was a broken wire at the ignition. the grey one that feeds F2 for side and tail lights. soldered and fixed. thanks jay for the real-time telephone tech support

 

[DrFarkoff]

Nice One The 1100/1150 allow you to fix things like that unlike the more and more frail successors!