Need help replacing a standard incandescent bulb with an LED bulb

We are having that similar problem, in that the 8 w CCFL lamps when replacing standard incandescent bulbs, tend to Flicker quite abit, and especially the more you dim them down. We just had to add some small incandescent load to the system.

Where we are using 60 pcs of 8 watt CCFL lamps, there, they also need at least 60 watts of incandescent lighting in order to take away all the flicker..

So, I imagine that those LED do not draw enough to count as working by the car computer. You will have to add a balanced load of incandescent somewhere, and that should take away that warning notice.

Donald

The Mitsubishi computer apparently wants to see the resistance to the 3rd brake lamps as the same as the incandescent lamp. Install a resistor in series with the incandescent lamp at the same ohm rating as the the incandescent lamp. You might have to compensate for the resistance of the LED lamp.

Many of the automotive LED lamp manufactures recommend and offer resistor to do this.

Error

Install a resistor in series with the incandescent lamp at the same ohm rating as the the incandescent (change to LED) lamp. You might have to compensate for the resistance of the LED lamp.

On typical cars, when you dont press the brakes, there is 0 volts at the rear 3rd brake light. On my car, when the key is on, it has about 1 volt.

I would like to ask if that 1V that you have measured was with incandescent bulb or with the LED one. If was the LED, what is this voltage with the incandescent?

A friend of mine who has the same car said it is 2 volts with the incandescent. I haven't tested that yet but I still have the bulb sitting in my drawer. I can do it if I need too.

Knowing how anal Japanese engineering can be, I'd bet a 5-spot that that ABS light and test system ALSO checks things like:

Low brake fluid level

Brake pad wear

Continuity test for burned-out brake lights

Along with checking the ABS system, too.

And it's BS like this that keep me buying German-build cars!

I'd bet a 5-spot that that ABS light and test system ALSO checks things like:

...Continuity test for burned-out brake lights

I think this is the problem and the question is what current (or voltage) would OK that check. The voltage on that incandescent bulb (it has to be accurately measured -tens or hundreds of mV) with the cold resistance of the bulb can give the answer.

Try placing a 12 ohm resistor (at least 12 watts rating and make sure that it does not touch anything as it will get very hot!!) across the wires going to the lamp (not in series as many others have mentioned, that will make the problem worse!), with the LED lamp installed, this should cause enough current to flow to satisfy the computer.

If not, reduce it to around 9 Ohms (increase wattage rating) or so......

I would recommend ceramic resistances as used in old TVs etc...

The reason for your problem is that the sensor for the computer is expecting a higher current flow than the LED gives. You just need to increase the current flow.....

Hi djturbojp7

I think I can see what's happening - your 50W 3 Ohm resistor is the right idea but wrong value - it would work fine but get as hot as hell and waste power. Because of the VI characteristic of the LED, when off with a small leakage current, you are getting the 1V drop - use a higher resistance value in parallel with your LED - I would try 2.2KOhm 0.5W to start with, and measure the voltage across the LED when "off" - it should be substantially lower than the 1V you are getting with no shunt resistor. If this still isn't low enough, just keep decreasing the resistor value, and as required increase the power rating, so the resistor runs fairly cool. Hope that works. Regards John

You need to get about same current draw when the brake is pressed.

So you need 1.87A or 2A on 12V V=IR R=6hom. P=VI P =24W. This will be the max current draw you'll need.

The system should work on a bit lower current draw. You can try lower current (higher ohm) say 1A, 12 ohm, 12W. You'll need to mount the resistor on body to help cool it down.

Read post #6 again, you could have saved yourself the bother!!!

Hey guys this is djturbojp7@yahoo.com again - thank you all so much for all of your replies! This is way more help than I have been getting in the Mitsubishi lancer evolution forums. I got my 50 Watt 6 Ohm resistors the other day in the mail and they look very similar to the 3 Ohm 50 Watt ones I already had. I haven't put a resistor in parallel yet but I plan on doing that tomorrow because its going to be sunny and easy to work on the car.

when i measured a 1 volt draw WITHOUT the brakes pressed i was measuring on both sides of the LED I had installed.

Here is a picture of the bulb I am using in there... It is a direct fit in replacement for the 7440 and 7443.

http://a763.g.akamai.net/7/763/1644/5/app.infopia.com/img/image/fp/VPID/4810366

I also bought today a socket that will fit a standard 7440 bulb. It was only 3.49$ - I figure that if the resistor trick dosent work, then I can put the incandescent bulb in parallel and hide it in the trunk. I'll never know its on because it will only brighten up when the brakes are on, and I never use the brakes when the trunk is open. This is a last resort, because I want to try and make the resistor trick work first. I haven't checked this post in a few days but I really thank you for all your ideas. I will update you all on my findings.

I am guessing a bit, but I suspect that the 1 volt just keeps the filament warm so that it is less likely to break when switched on fully.....Cold filaments quickly break.

I am sure an automotive design engineer could tell us if my idea is correct or not!!

LED = no filament

See here: www.elecosn.com

Here are dimmable LED Bulb, and LED incandescent bulb

Here is a picture of the style resistors I am using.

http://a763.g.akamai.net/7/763/1644/-2/app.infopia.com/img/image/fp/VPID/4783296

both the 6 and 3 ohm look the same, they are pretty big (2 inches or so) and have heat sinks. They are 50 watt rating.

Should be good....

Ok - now this I don't understand.

I just hooked the 6 ohm, 50 watt resistor in parallel with the LED i was using as my 3rd brakelight. It seemed to operate perfectly, (light went on when I hit the brakes, I used a mirror so I could see)

Before I hooked the resistor in parallel it was measuring 1.11 volts when I did not press the brake. Now I took the same measurement with the resistor in parallel and I get 0.16 Volts, yet is seems to work right. I need to still drive the car for 20-30 minutes to really test if I get the same error. I will let everyone know tomorrow.

Its simple Ohm's Law. There is a series resistor in the car (somewhere) that allows only (before) 1 volt. Due to the fact that you now actually are drawing MORE current than before ias you are using a 6 Ohm resistor, the available voltage has dropped.

This means that you may be stressing or heating up this unseen resistor more than it can take by the way, sometimes design engineers for cars design exactly and you have "overstepped" this, which is EXACTLY why I suggested to start at 12 Ohms in the first place, erring on the side of safety!!!

I am sure about 2 things, 12 Ohms would have the current you are now drawing, so halving the heat in this unknown, unseen resistor, halving the heat dissipated in itself and would still have an excellent chance of fully and correctly doing what you wanted to do in the first place!!

Also, you guys were right, those little buggers get hot! - I nearly burned my fingertips. Can I double sided sticky tape the resistor to the inside of the body?

I doubt if such tape would handle the temperature. you need a proper mechanical connection.

Doubling the value to 12 ohms would halve the temperature developed.....as I mentioned in several previous posts.....

Hey guys I finally registered... no more "guest" posting

I just double checked. If I unplug the entire bulb I measure 1.03 volts with the key on, brakes off. When I plug in the LED/resistor assembly I get 0.16 volts with the key on, brakes off.

here is the picture of what I am using.

I posted a couple of minutes ago telling you exactly what is happening and why as well as giving a fix......your 6 ohms is far too low.....try 12 or even 18!!!

Higher values may still do exactly what you want, but with far less current and far less heat being developed.....

3 Days and 3 trips to work, no problems working good so far. I will increase the resistance if I get a full clean week or 2.