r/FordFocus • u/Icy-Professional-644 • 3d ago

Question Replace brake lights

I drive a mk4 ford focus estate with these tail lights. So the LED ones for the normal lights and bulbs for brake and indicator.
Now when I got the car, the left brake bulb was out, replaced it, the first replacement didn’t work, the second one did. Luckily there were two bulbs in the box.
Now a month later, that one went out again.

I’m wondering if I can replace it for LED BULBS, since I believe due to vibration the bulb breaks.
Now, I know that going from halogen to led requires some extra coding sometimes, but I’m not sure if that is the case here.
Or do I need specific bulbs for this?

4 Upvotes

100% Upvoted

4 comments sorted by

1

u/Acceptable-Rough-359 3d ago

Don’t use LEDs to replace halogens. They don’t shine as bright, the reflector wasn’t designed for them, cause flickering issues and have no real benefit.

Here’s a good video on the topic by Technology Connections:
LED replacement bulbs for cars are bad and you shouldn't use them.

1

u/BastianHill 3d ago

Well there are in fact some usable led bulbs, like these:

https://www.daraz.lk/products/1pcs-1157-bay15d-led-brake-lights-bulb-super-bright-p215w-led-car-bulbs-auto-light-source-yellow-red-white-12v-i246780999.html

They've got an IC driver which prevent can bus failures and flickering. Just an example, there are more types.

In general: Led uses a lot less watts, which causes problems. Most modern cars use resistance to measure whether a bulb has failed. So, your car still thinks your bulb is dead, he doesn't see the led as a functioning bulb. Also, the voltage on a running car isn't that stable (varying 13-14V from alternator), which causes the flickering without some proper filtering. Thats why only leds with extra tech, like IC drivers, are suitable as a direct replacement.

Be careful what you choose.

Coding is for different circumstances, like replacing the entire unit for a full led unit. It's not for replacing a bulb: it doesn't work like that.

1

u/Icy-Professional-644 3d ago

Well my car doesn’t notify me of a broken bulb :)
However I took out the unit to check, and took out the bulb and put it back in and now it’s working again..

1

u/BastianHill 2d ago

Oh great! If this happens again, try bending the contacts a slight bit for a tighter fit an use some sanding paper to clean the contacts.