Board logo

HELP: Rear Brake Light Issue after fitting LED Bulbs
smitht82 - 16/1/13 at 01:14 PM

Hi Guys,

I'm still having Brake Light issues after fitting LED bulbs. I'm hoping someone can point me in the right direction as i have no more hair to pull out!

Basically i bought a set and fitted them and immediately noticed that the brake lights where on their brighest setting (ie: as if the pedal was pressed). I checked the pedal box and there is no switch here. The car uses the original R1 loom which has been extended by the original owner. I have therefore looked under the bonnet and found a pressure switch. I have disconnected the 2 spade terminals and the lights remain the same. I have then checked all fuses and these are ok.

I'd understand if i had fitted higher wattage bulbs, but lower current LED Bulbs shouldn't have caused an issue. I've even tried the original bulbs that i took out and they have the same issue.

Has anyone got any ideas?

adithorp - 16/1/13 at 01:34 PM

So they're stop and tail bulbs from the description? Sounds like you have managed to get the bulbs fitted the wrong way around. he pips on the side are offset to prevent that but it is still posible.

smitht82 - 16/1/13 at 01:36 PM

quote:
Originally posted by adithorp
So they're stop and tail bulbs from the description? Sounds like you have managed to get the bulbs fitted the wrong way around. he pips on the side are offset to prevent that but it is still posible.


Sorry, i forgot to say that i've already tried turning them 180' incase the holders were loose but they will only go in one way round anyway due to the pin position.

ReMan - 16/1/13 at 01:42 PM

In which case swap the wires over?

owelly - 16/1/13 at 02:49 PM

I replaced my stop/tail lamps for LED ones and had the same problem. It was because of the way the LEDs were built with the LEDS sharing the same feed inside the lamp but getting a higher signal for the brake function. In my case it also turned my high level brake lights into stop/tail lights. ie, they were on dull all the time with the tail lights and full brightness with the brake pedal pressed. I just swapped back to normal filament lamps!!

smitht82 - 16/1/13 at 03:10 PM

quote:
Originally posted by owelly
I replaced my stop/tail lamps for LED ones and had the same problem. It was because of the way the LEDs were built with the LEDS sharing the same feed inside the lamp but getting a higher signal for the brake function. In my case it also turned my high level brake lights into stop/tail lights. ie, they were on dull all the time with the tail lights and full brightness with the brake pedal pressed. I just swapped back to normal filament lamps!!


I've tried the original bulbs and still have the same issue so i'm now wondering if i have an earth fault

Slimy38 - 16/1/13 at 03:19 PM

Without blinding yourself, can you see whether both filaments are actually active or whether it's just the brake filament? If I remember rightly a dual filament bulb has one filament either side of the earth shell, so if both filaments are lit you do have an earth fault.

Look at it through a welding mask if you can't quite tell what filaments are lit.

smitht82 - 16/1/13 at 03:30 PM

quote:
Originally posted by Slimy38
Without blinding yourself, can you see whether both filaments are actually active or whether it's just the brake filament? If I remember rightly a dual filament bulb has one filament either side of the earth shell, so if both filaments are lit you do have an earth fault.

Look at it through a welding mask if you can't quite tell what filaments are lit.


Both filaments on the original bulbs are most definately on . Need these now

loggyboy - 16/1/13 at 03:31 PM

How many connectors/contacts on the new bulbs?

smitht82 - 16/1/13 at 04:19 PM

quote:
Originally posted by loggyboy
How many connectors/contacts on the new bulbs?


2 contacts for the 2 filaments and 2 bayonet points at slightly different heights.

loggyboy - 16/1/13 at 04:23 PM

Check your fuses too.

puma931 - 16/1/13 at 04:47 PM

Check the voltage on the side lights and brake wires, as it sounds like you have +12v on both, but the brakes are not on.
Work you way through it with a meter and you will find the cause of the problem, although it does seem strange there was no problem before fitting the new bulbs, and you now have the same issue with the old bulbs.

minitici - 16/1/13 at 05:32 PM

I usually find that strange behaviour of brake and rear sidelights is due to faulty earths.

GOJO - 16/1/13 at 07:32 PM

If theres power 12v (using a multimeter ) on the brake switch wire into the lamp theres a short or the pressure switch you have found is just a switch for a relay to supply the brake light, or theres another pressure switch near the back and the one you have found is a clutch switch??

smitht82 - 7/2/13 at 04:51 PM

UPDATE:

Managed to get the time to test the brake system and replaced the brake pressure sensor and can confirm its not that. I alos got my mate to sit in the car and pump the brake pedal. If the bulbs are inserted correctly then they still come on on full power (both elements lit up). If i then turn the bulbs around 180' (not in properly) and rotate the bulb slightly in the holder then the bulbs start to operate as they should?

It's as if the negative and postive have reversed themselves?

Now i'm stumped. I'm going to take it to the local garage and get them to test the electrics to get this resolved as i think i've got to the point were its going to be something simple (to the point that im missing it).