" Cruise Control "

[RNRea]

Even if the flasher is an electronic one, the LED bulb is designed to replace a regular bulb and has to work with thermal flashers, so it would have the resistor anyway.

[ypelchat]

Originally Posted by RNRea

Even if the flasher is an electronic one, the LED bulb is designed to replace a regular bulb and has to work with thermal flashers, so it would have the resistor anyway.

The purpose of an electronic flasher, is to provide the same flashing speed, regardless of the load. An electonic flasher will flash at the same speed, even if the bulb is burned. If you have an electronic flasher, and want to use LED bulbs, instead of the incandescent ones, the resistor is not needed.

Yves.

[RNRea]

You missed the point of my post. The company that makes the LED bulbs doesn't know what type of flasher will be used with their bulb replacements, so they have to make on that will draw enough current to make the thermal flasher work. For this reason they put the resistor in. You don't have a choice on what they put inside the bulb - the resistor is there whether you need it or not.

[ypelchat]

Originally Posted by RNRea

You missed the point of my post. The company that makes the LED bulbs doesn't know what type of flasher will be used with their bulb replacements, so they have to make on that will draw enough current to make the thermal flasher work. For this reason they put the resistor in. You don't have a choice on what they put inside the bulb - the resistor is there whether you need it or not.

A typical LED (Light Emitting Diode), operate at a voltage range of between 1.5 to 4 Volt. As you can see, this voltage is far below the 12.0V to 14.4V, normally seen in a car's electrical system. A 4 Volt LED would burn instantaneously at 12V. Therefore, to operate at 14.4V, each of the LED's must have it's own resistor, wired in series to the cathode of the LED. This resistor will create the proper voltage drop that's needed for the normal operation of a 4V LED, at 12V.

An LED bulb is built using an array of individual LED's (some LED bulbs have as few as 4 LED's, and some LED bulbs have 40 LED's or more).

40 LED's.... 40 resistors. (Anyone wonder why LED bulbs are so expensive.. ) However, some unscrupulous LED bulb manufacturers, are cutting corners, and put only ONE big resistor, for all 40 LED's, (instead of putting all 40 resistors) in order to decrease the manufacturing cost of the LED bulb....


In addition to the resistors, another diode must be added, to protect the LED bulb against possible polarity reversal.

In fact, the LED bulb's built-in resistor, is there, only to adapt the LED bulb's to the vehicle's voltage. It was never meant to adapt the LED bulb to a thermal flasher. In fact, if your vehicle is equipped with a thermal flasher, and still want to use the newer LED bulbs, in most cases, you will have to ADD another resistor. The added resistor (wired in parallel) will decrease the resistance across the LED, thus providing the correct load for the thermal flasher to operate correctly, and flash at the correct rate.

If you're using an electronic flasher, you don't need the additional resistor, because the electrical switching circuitry (the circuitry that actually apply the voltage to the load) is independent of the timing circuitry (that determines the flashing rate).

If it would be possible to post an attachment, I would draw a typical LED bulb circuitry, and post it here. To help you further in your understanding of how LED's operate, i've searched the internet, and found 3 interesting links that explain the basics of LED operations..


http://www.kpsec.freeuk.com/components/led.htm

http://www.the12volt.com/ohm/ohmslaw.asp

http://www.ledtronics.com/datasheets...auto_index.htm

Yves.

[RNRea]

You're not telling me anything I don't know. What you're describing is what *you* would do if you were going to make an LED replacement for an automotive bulb. If you are a company that markets the LED bulb as a *replacement* bulb then you have to make one that will work in all the vehicles that it could be used. If, for example, I want to replace the brake/turn-signal bulbs in my '67 Mustang with LED bulbs, and I pay $32 for the pair, I expect them to work. Without a shunt resistor they'll be drawing 10's of miliamps rather than the couple of amps that the old bulbs drew. So the bulbs won't flash with the old thermal flasher. If I am a regular kinda guy, I don't think about needing to draw more current for the flasher to work. I think "I paid 32 bucks for these things, and they don't work. I want my money back." The LED bulb maker doesn't want to take back product that is good. So they throw in the resistor so that it will work with either type of flasher. That's why it's there. If you don't want the shunt you could take the thing apart (good luck) and pull it out, but the manufacturer still puts it in there.

[ypelchat]

Originally Posted by RNRea

You're not telling me anything I don't know. What you're describing is what *you* would do if you were going to make an LED replacement for an automotive bulb. If you are a company that markets the LED bulb as a *replacement* bulb then you have to make one that will work in all the vehicles that it could be used. If, for example, I want to replace the brake/turn-signal bulbs in my '67 Mustang with LED bulbs, and I pay $32 for the pair, I expect them to work. Without a shunt resistor they'll be drawing 10's of miliamps rather than the couple of amps that the old bulbs drew. So the bulbs won't flash with the old thermal flasher. If I am a regular kinda guy, I don't think about needing to draw more current for the flasher to work. I think "I paid 32 bucks for these things, and they don't work. I want my money back." The LED bulb maker doesn't want to take back product that is good. So they throw in the resistor so that it will work with either type of flasher. That's why it's there. If you don't want the shunt you could take the thing apart (good luck) and pull it out, but the manufacturer still puts it in there.

http://www.ledtronics.com/ds/aut3157/

[RNRea]

Good link. I was basing my info on the local auto parts store's replacement version (don't remember which brand, but were for 1056 or 1057 bayonet base bulbs). Funny that they sell a load resistor that costs more than my electronic flashers though. Anyway, why were your sockets melting even with LED bulbs? Where was the heat coming from?

[tpjankowski]

Thanks to everyone who mentioned checking the the BRAKE LIGHTS. I found this forum and read a bunch of entries and checked today. I've been driving around for about a month without my Tail light brake lights working. The only one that worked was the top bar on the cargo door. Oh and it got my cruise control working. But the sockets are corroded. Any ideas on where to get a good replacement that doesn't break the bank. Thanks

[rkvons]

Originally Posted by tpjankowski

Thanks to everyone who mentioned checking the the BRAKE LIGHTS. I found this forum and read a bunch of entries and checked today. I've been driving around for about a month without my Tail light brake lights working. The only one that worked was the top bar on the cargo door. Oh and it got my cruise control working. But the sockets are corroded. Any ideas on where to get a good replacement that doesn't break the bank. Thanks

Try amazon.com. They are about $13. What you do is search for "Brake & Tail Light Assemblies" for your vehicle.