LED rear light issues

[pete275]

OK, slight issue with LED dual filament replacement cree type bulbs in my Chim

Basically they are on "full" brightness all the time (whether the brake pedal is down or not)

The switch is fine and recently replaced, I'm assuming a voltage must be present on the brake light terminal for the bulbs in the boot from somewhere? Or could it be a bad earth?

When I switch back to conventional bulbs they work fine.

any thoughts appreciated

[ChimpOnGas]

Interesting, I'm about to ditch my LED rear light bulbs.

They used to work fine with standard headlight bulbs, but since I went with the LED H4s my rears started to flicker/strobe.

Shame really as the extra bright rear lights were a good safety aid, but I'm not ditching the LED H4 headlights just to stop the rears strobing, I'd rather just go back to the standard incandescent stop/tail bulbs.

But I wonder if there's a fix for strobing LED bulbs?

[mk1fan]

I think it's a wiring issue.

The LEDs ony need a small amount of wattage to produce light. As a test have you tried running a dedicated earth to the rear lights?

[pete275]

thanks for the suggestion, I'll give it a try tonight.

Does anyone know where the rear lights earth to on the chassis? I'll check that as well.

I've emailed the supplier and they reckon fitting a resistor will help, I thought that was more for canbus type cars with modern electrics?

[Pink_Floyd]

pete275 said:

Does anyone know where the rear lights earth to on the chassis? I'll check that as well.

Behind the petrol tank. So not that easy to check. I would use a meter and check the resistance from the bulb negative to the battery negative terminal.

[Pink_Floyd]

pete275 said:

OK, slight issue with LED dual filament replacement cree type bulbs in my Chim

Basically they are on "full" brightness all the time (whether the brake pedal is down or not)

The switch is fine and recently replaced, I'm assuming a voltage must be present on the brake light terminal for the bulbs in the boot from somewhere? Or could it be a bad earth?

When I switch back to conventional bulbs they work fine.

any thoughts appreciated

Are you saying that without the side lights being on and without pressing the brake pedal that the lights are on?

[pete275]

Hi yes the light runs at full brightness. I've ruled out the brake light switch its the same on both rear lights

[AV8]

Could also be a faulty bulb. When I bought a pair of Cree's one of them was faulty and exhibited similar symptoms and when it was replaced they were fine.

Fit them one at a time, swap them over, and then fit them in another vehicle (I tried mine in a Pugeot) to be sure you haven't got a faulty one.

Mine work fine and are a a lot brighter than the originals.

[pete275]

AV8 you are spot on, didn't occur to me to be honest, thanks for the idea

Tried both bulbs in another car. One is perfect, the other is fine for a few seconds then runs at full brightness, so I suspect some kind of internal LED fault

Contacted the supplier hopefully they'll replace them.

[ChimpOnGas]

I've lost faith in the reliability of these cheap Cree LED stop/tail bulbs.

I think I'm going back to old school incandescent filament bulbs, saying that I'll not be giving up my LED super powerful headlight bulbs in a hurry

Its probably just a quality issue with the rears so I'll wait until Osram or Phillips start making them properly.