Hi,

Can somebody help. I have a Hyundai i30 2007 UK and I have recently installed led lights to the main brake lights. I also installed 50w resistors as if not I would get a message / symbol on the dash to advise that the lights were blown as led produces less power. All was ok and very easy to install however the 3rd brake light will not come on anymore. I've done some troubleshooting and removed the 3rd light and tested it on my battery and it lights up and works. I have also used a test light and tested the cable that connects to the 3rd light and power is running through it when I press the breaks. I have also checked every fuse and all seems ok. Unless there is a separate fuse for the 3rd? Also I have removed the LEDs from the brake lights and the resistors and put back the original halogen ones but the 3rd still won't light up. I have not checked the brake switch but I really don't think it could be that? The way I connected the resistors to the brake lights was by cutting and bonding together the ground and power wires and then electrical taped it all up ( probably not the best way to do it). Does anyone have any idea what's going on?. Any advice would be appreciated.

[mickd]

Hi,
OKAY,
3rd light works when connected to straight to battery - light ok.
You have power at 3rd light cable when brakes are used - good - hopefully 13 volts. So  fuse good , would assume no specific fuse for 3rd light.
Sorry but how did you connect the resistor? ( tired brain - cant think so well today)
Inline with the leds (series) or
across the cct (parallel )
Also , 50 watt resistor who recommended that?

[The Gonz]

Even assuming you're using the right value resistors and in the right way, you said that when you reverted to original globes there is still a problem. That tells me you still have a problem in how you've made your connections. Twisting and taping results in poor connections, especially in a vehicle that moves and is subjected to temperature and moisture variations.

[Shambles]

The way I connected the resistors to the brake lights was by cutting and bonding together the ground and power wires

Can you elaborate on where the resistor is installed? If it's connected between ground AND power wires it's gonna get quite hot and may be the cause of your problem. I believe it should be serial in the power line only.

What value resistor did you use?

Thanks for the replies. Ok, so I guess I really didn't look into well enough before doing the job. I ordered just a standard 50w resistor, I didn't do my research and just went out and got them online. It came with t caps but I found that they were no good at all for connections so I then decided to cut the wires (there were 3 in total) a black neutral and 2 coloured ones. I found out  which one was the brake wire and so I connected it to the power brake wire and the neutral. This worked out fine and removed all warnings from the dash. Yes they get very hot and reading up on it now they say not to have it too close to plastics or wires as it can burn and melt it. They recommend to mount it on the cars metal work. It got hot and melted some of the plastic from the back of the light housing however no damage has been done to any of the cables. Update.. I have been using the light tester on the 3rd lights cables and notice there is power running through when I hit the breaks. The strange thing is that whenever I touch the neutral wire I get some light coming through the 3rd!! I tried then to use a piece of cable touch it on the nearest bolt and inserted the other end of the wire into the neutral connection and it works fine with full light power. Strange don't know why that happens. Any ideas on this?

[Shambles]

I believe it should be serial in the power line only.

You should only have needed to cut one wire - the power feed. The resistor should be in the power line only, as its only function is to present a resistive load to the BCM to fool it into believing there's a filament type bulb in circuit.

[Dazzler]

Wow! What a clever and helpul bunch of members we have. Such good observations and smart suggestions. I might be biased, but what an awesome car forum.