tail lights dim when indicating

[stephen123]

hi i have a problem with a gsf 600 k3 bandit. it failed its mot for the tail light dimming when the indicators are turned on. The garage say they think its an earthing problem. does anybody have any ideas.

i have checked the battery voltage which is good, have checked alternator although it still does it when the bike is not running. the voltage of the battery appears to drop .5v when idicators are on and testing the amount of current drawn from them it is 3amps so 1.5amps each. which from a 21w bulb is about right.

i have tried giving the tail bulb power directly from battery but the potential difference of the battery drops and rises with the indicators. tried giving it an earth straight to battery as well when the bike is running it charges but the voltage still fluctuates by .3 of a volt which gives the appearance that the lights are flickering a bit.

any help or suggestions are welcome

thanks

[Aff]

Have you actually checked the brake lights earth?
____________________
Current Bikes:Honda 929RR Fireblade, Honda CD200 Benly (Project), Stomp Z2 140
Electric Bike Project

[Casper]

In what way did you check the battery voltage?

[Walloper]

Check all the bulbs, contacts and earthing.

The problem is an earth leakage.
____________________
W-ireless A-rtificial L-ifeform L-imited to O-bservation P-eacekeeping and E-fficient R-epair

[stephen123]

I checked the battery voltage with a multimeter across battery terminals when tail lights are on 12.4v when indicotor is turnwd on voltage drops to 11.9 thwn goes back to 12.4v in time to indicators .n
I have given the brake lights /tail lghts a a direct earth to the neg on battery terminal. Even with brake tail lights totally disconnected if you put I dicators on dials dim slightly, headlights dim. I disconnected alternator starter motor all connectors to handle bars bar the indicator switch, disconnected headlights carb heaters, brake switches. Toook earth off chassis as everything should be wired back to battery apart from starter motor which is chassis earthed and alternator.

[stephen123]

I checked the battery voltage with a multimeter across battery terminals when tail lights are on 12.4v when indicotor is turnwd on voltage drops to 11.9 thwn goes back to 12.4v in time to indicators .n
I have given the brake lights /tail lghts a a direct earth to the neg on battery terminal. Even with brake tail lights totally disconnected if you put I dicators on dials dim slightly, headlights dim. I disconnected alternator starter motor all connectors to handle bars bar the indicator switch, disconnected headlights carb heaters, brake switches. Toook earth off chassis as everything should be wired back to battery apart from starter motor which is chassis earthed and alternator.

[Walloper]

[stephen123]

The battery is good I took my car battery off and hooked it up. Rigjt my line pf thinking is this if the battery is losing .5 volts then it must be drawing a lot of current. When I test current draw its 8amps the battery is rated at 8ah so should last for an hour with these things on. If the voltage of the battery drops then of course the lighrs would dim as they have .5 of a volt less dropped across them which means less current. So my problem seems to be why the battery voltage drops with this amount of currwnt being drawn. Im going to check on my car how.much the voltage drops when indicators are on.

[Walloper]

[stephen123]

Ok I think I have found the fault. I got my sympton tedt results slighrly wrong. I check how much the indicators on my car changed the internal voltage when operated it was 0.07 volts so rhen I rested on bike at battery it to was 0.07 - 0.09 so then I moved on to the fuse which powers all the lights regardless of what is says on the fuse cover (signal) it actually privides power to dash side lights indicatir. Well anyway at this point you get .4 of a volt drop so its magnified so when you test power at tail drop .4 volt instead of .07 which gives appearance of light dimming with indicators. So the actual fault there is a slightly higher resistance in the line from the fuse back through ignition battery back to main battery terminal. Thanks for everyones help it stumped me for fours days this one. If any body else gets a similar fault check you tube as I will make a video of my finding to help people in future

[stephen123]

Ok I think I have found the fault. I got my sympton tedt results slighrly wrong. I check how much the indicators on my car changed the internal voltage when operated it was 0.07 volts so rhen I rested on bike at battery it to was 0.07 - 0.09 so then I moved on to the fuse which powers all the lights regardless of what is says on the fuse cover (signal) it actually privides power to dash side lights indicatir. Well anyway at this point you get .4 of a volt drop so its magnified so when you test power at tail drop .4 volt instead of .07 which gives appearance of light dimming with indicators. So the actual fault there is a slightly higher resistance in the line from the fuse back through ignition battery back to main battery terminal. Thanks for everyones help it stumped me for fours days this one. If any body else gets a similar fault check you tube as I will make a video of my finding to help people in future