True CANBUS error free LED red brake lights.

**GTI JOE** · 16-02-2013, 02:44 PM

Hi Guys,

Just wondering if anyone out there has installed LED red brake lights that ARE TRULY ERROR FREE?

Just purchased some off Ebay (not exactly cheap) and they throw up check light error

Link is Upgrade Car Back LED Tail Light Bulbs 382 P21W RED SMD Canbus No Error Free 12V | eBay

Willing to even try the CREE type if they are any good

**wai** · 16-02-2013, 03:03 PM

By the way, if you have a coloured tail light lens, you might not get what you expect if you use a coloured LED.

Basically, the reason you see a red light is because the lens absorbs all the colours except red and passes that through. If you use a red light and the characteristics of the red light does not match that of the tail light lens, you will find that the lens might absorb some of the light produced and pass only that the lens allows through. This is basically why the original bulbs are not coloured.

I went through this exercise on my last vehicle (Hiace ABV) where I fitted LED bulb replacements. The set I got had a coloured dome, and the light coming through the lens was very dull. Dremel tool and a little time saw me cut off the coloured dome and the light seen through the lens improved dramatically.

By all means, you can get the coloured LEDs, see if you can check them out before you buy. The white ones might be better.

**nomadx38** · 16-02-2013, 05:23 PM

Yep agreed with pervious post.

Also ALL LED bulbs will throw up an error becuase the use less power (and thus less resistance) than filament bulbs. To get around this you can put a load resistor in the circuit (but it is a lot of work!) OR you can just plug in your VAGCOM and go to central electrics II and disable diagnostics on the circuit (Brake/indicator/parking light circuit)

**GTI JOE** · 16-02-2013, 05:54 PM

I do understand all of what was said above, just trying something on my car. So I guess there is no true error free led lights out there.

Thanks nomad, didn't realize that the check light feature can be disabled, might try this avenue or just live with the instrument light on..no biggy.

**ecks** · 16-02-2013, 07:08 PM

Originally Posted by nomadx38

(and thus less resistance)

Nah ah - more resistance

**nomadx38** · 16-02-2013, 06:15 PM

No probs, at the next get together I will probs bring my VCDS cable so people can fix their cars up, so if one is organised I can do it then.

**GTI JOE** · 16-02-2013, 06:48 PM

Originally Posted by nomadx38

No probs, at the next get together I will probs bring my VCDS cable so people can fix their cars up, so if one is organised I can do it then.

Much appreciated mate

**nomadx38** · 16-02-2013, 08:17 PM

No less resistance in this situation. the electrical system is looking for a load of .41amps (5 watts divide by 12 volts = .41Amp for a w5w Parker). When the system sees it it using less power than this (+ or - 10% or so) it displays the circuit as been open. A 1watt led is only pulling .08 amps as is counted as blown.

A 100w incandescent bulb is brighter becuase of the resistance that is created by going through the very thin wire (a bottle neck) and the resistance is displayed as visual light, a by product of heat.

A 25w incandescent bulb is duller because of the thicker wire allows more power through and thus less resistance, and equals less heat/light.

The point of a load resistor is to put extra load onto the circuit to make the computer think there is a bulb.

Actually I'm happy to be corrected, it has been a while since I did my studies with Ohms Law and resistance so I'm a little rusty. I always pictured it as a freeway. Traffic will flow faster (and thus less resistance) going from 3 lanes to 2 lanes than going from 3 lanes to 1 lane.

**GTI JOE** · 17-02-2013, 08:19 AM

Yep^^^ the LED is showing less resistance to the electrical management unit, that's why the check light is coming on, thinks something is blown.

I would also imagine that the load resistor would be dissipating a fair bit of heat, so it would require some form of heatsinking.

**ecks** · 17-02-2013, 08:23 AM

Originally Posted by GTI JOE

Yep^^^ the LED is showing less resistance to the electrical management unit, that's why the check light is coming on, thinks something is blown.

I would also imagine that the load resistor would be dissipating a fair bit of heat, so it would require some form of heatsinking.

NO NO NO, it's showing MORE resistance, therefore LESS current is flowing!