LEDs Brakes Interfering with Illumination System

by **mynameisdaniel** » Mon Apr 22, 2013 8:46 pm

Recently replaced the brake lights in my tail lights with Cree LED bulbs. Now when I press the brakes (key in any position or out, lights in any position) the illumination system is activated partially. This results in the system either flickering or illuminating very dully. The effected items are:

Everything else works perfectly, I suspect it's the dual filament bulbs and how they work, perhaps sending some reduced voltage through the illumination ground which is connected to the rest of the system? If it was the reduced resistance I'd suspect other people would have the same issues. These bulbs are really good so just wondering if anyone has any ideas on how to fix this as I can't seem to work it out... Would an independent ground for the tail lights work?

Here's the wiring diagram.
https://www.dropbox.com/s/3c8wwik9csplw ... System.pdf

EDIT: I should also mention it's not the battery, car starts fine and also does the same while the car is running. (Dull illumination, not flickering though)

by **RX25SE** » Mon Apr 22, 2013 10:06 pm

Sounds like the globes a feeding a voltage back up the parker circuit.
A dedicated earth for park and brake will not solve the problem.

You may need to fit a diode to the park lamp circuit but this may upset the LEDs are they a polarity sensitive.

I have to ask, what was wrong with the original globes?
Mine had LEDs all through the interior and the first thing I did when I got it home was pull them out.

Not a fan personally.

by **mynameisdaniel** » Mon Apr 22, 2013 11:29 pm

Yeah diodes might do it but I don't want to modify my stock wiring unless I have to... As far as I can tell the circuit feeds +ve power so as long as the diode's in the right way it shouldn't make any difference.

These are 5 times brighter and come on a lot faster than the stock bulbs, I've always liked the euro cars with LEDs that come on instantly for some reason

by **mihai** » Tue Apr 30, 2013 4:39 pm

Ive had a similar issue with the illumination circuit when I had a trailer connected.

Everything illuminated when I applied the brake, and when the indicator flashed.

Very weird!

by **agan** » Tue Apr 30, 2013 11:02 pm

That's happened to me last time - it was cause one of the bulbs was sorta faulty...I changed the both out and they were okay.

In my case..the third brake light was on the whole time also (I think).

by **Johnhasler** » Wed May 01, 2013 8:12 am

Are all those lights LEDs or just the brakes? Probably not this but try and put one filament bulb into a fitting and see if it still happens, could possible be an induced voltage from somewhere and as LEDs are a capacitive load they can build up and discharge, but maybe not to that extents, might be worth a try

by **agan** » Wed May 01, 2013 8:53 am

In my case just the brake lights.