brake electrical problem on the 748

[monsta]

Buggered if I know!! 

3 wires. 1 for brake light, one for tail light, one earth..

Tail light works fine.

I get power to the brake light wire when the globes (there are 2 on the 748) are removed, but when I fit just 1 (either one) globe there is no power...

therefore no brake light???
Why does the power to the brake light drop out when I fit the globes, when tail light works fine.

Also, I wouldn't have thought you would get continuity across the two positive's on the globe's but you do?


PS, they call me 'tail light' at work... they reckon I'm not bright enough to be a brake light!   

[Howie]

My memory could be wrong, but I believe what you have back there is two double filament bulbs globes, one filament for tail and one for brake.  Probably your brake filaments are gone and the brake filament touching the tail filament would explain the continuity.  Try a new set of globes.

[monsta]

yeah, they were the new ones....

I'll go and get a couple more today to wipe that from the equation ...

[monsta]

new bulbs...  no go.

noticed that when the ignition is off, there is continuity between the wire that connect to the power side of the tail light, to earth.
the same doesn't happen when I connect to the power side of the brake light (actuating the lever)

[Howie]

Ignition off there should not be continuity to ground at the tail light.Sure you have the correct wires?  Got a wiring diagram?  Continuity from hot to ground indicates a short to ground if I understand what you are saying correctly.  Could be someone buggered the wires or you are putting the bulbs globes in backwards.

You can find the wiring diagram for your bike here  http://www.ducati.com/services/maintenance/index.do  if you download the owner's manual for your bike.


       

[monsta]

Thanks howie. 

Finally got it sorted.  The mutimeter was picking up voltage, but when you put in the globe it wasn't getting anything.

I bought a test lamp, one of the ones that look like a screw driver but with a spike instead of blade.
That puts a load on the circuit were as the multi doesn't (I learnt something  )
turned out to be a bullet plug that feeds the switch on the front brake lever had high resistance, so when you measure voltage you have it but when theres a load no go...

Simply cleaned and refitted.