LED Brake Lights - Residual Current?

[Hardy]

G'day.

Brake Lights are always on, but dim!

Much brighter when brake pedal is pushed, nothing to do with tail lights.

Have just swapped out old school taillight packs from trayback with new LED kits. It seems there is a small amount of current in the brake light circuit, even though the 'car is off', key out, nothing on pedal, even with brake switch disconnected.

It would seem this small current was always there, I'm assuming that because the LEDs draw less current they are able to operate - only just.
Car is MK Triton, no other known electrical issues.

Any ideas?


Thanks,

Hardy

[awill4x4]

Hardy, have you got a Tekonsha Voyager electric brake controller wired in?
If so, they are well known to cause the problems you describe.
Regards Andrew.

[-Scott-]

Hardy, have you got a Tekonsha Voyager electric brake controller wired in?
If so, they are well known to cause the problems you describe.
Regards Andrew.

I think Andrew must be pretty close to the mark.

There's no reason for an LED to "create" leakage of any kind; it's more likely that the low voltage that is present for whatever reason (e.g. accessory wired in) is enough to produce noticeable light from the LEDs, but not from a traditional incandescent globe.

So what else is attached to your brake circuit?

[Hardy]

Hi guys,

No brake controllers, nothing else.

It's just a Jap ute. When I installed the tray I cut the light wires before the plugs (so old tub was easy to install for new owner).

I did have problem with the horn recently. It came on all by itself, was a dodgey relay. Maybe this is something along the same line, I'll have to investigate more tonight.


Thanks.

[mkpatrol]

Go back & have a look at your joins & the your earths. Sounds like a join or your earth is dodgy. Also check your trailer plug, they can also give you these issues.

[drr]

I had the same thing happen to the interior light of my old Camry when I swapped it for an LED, that light is controlled by the computer so I just thought it was a bit of transistor leakage current. No idea why it would be doing that on a brake light circuit though, especially since it does it with the brake switch removed. Your best bet is to get a multimeter and have a poke around.

[GUtripper]

We had an issue recently with LED lights in a trailer (they were flashing when brake was applied, and also dimly staying lit when brakes weren't applied), I believe the auto sparky fixed it by wiring in a diode to the brake light circuit on the trailer.
Will check for sure next time I talk to them.

[Leeroy]

BA Falcons do the same thing; just wire a load resistor in parallel fixes it, the type you would use to stop indicators flashing too fast when replacing globes with LEDs.

[Hardy]

Hey guys, thanks for all your suggestions.

Yep - I checked all joints & wiring, isolated each feed etc, even made a new earth back to chassis - no change.
Like Leeroy said, it must be a thing that some cars just do.

Fitting a 21w load resistor works perfectly and in this case removing the symptom is a lot easier than removing the cause!!


Thanks again,

Hardy