glassJAw

Just wanted to post a quick question. I did the L.E.D. license plate bulb modification about three weeks ago and today I noticed my right bulb now flickers. Just wondering if anybody else had this happen??

I figured it's a bad bulb so I ordered a couple more.

ghaffar23

Did you order some load resistors along with them? Try that, and if that doesn't work, then I don't know what will work. In the other thread, every has had regular resistors on the festoons, but they still blew out. My theory is that the load resistors will help this out. Please let us know. Thanks!

-Ghaffar Glenn

glassJAw

I wired in the suggested resistors in-line with the bulbs to prevent the bulb malfunction warning on the cluster. Is that what you're talking about??

ghaffar23

I was actually referring to the load resistors...I believe they are different from the 'regular' resistors.

FlatlineEF9

It happened to me too, even with the resistors in place. I just threw the bad one away and used the good one for one of the lights on the door.

Ben'z

After three LED festoons failed, I came back using OEM yellow light.

EdzBenz

I have one side flickering as well. I'm going to try and mess with it this weekend.

glassJAw

Don't bother messing with the bulb that's flickering, I've already tried.

It seems like this LED failure is a common thing. That's kinda disappointing. I really like the way they look.

rob_fed

Yes, LED bulb retrofits fail because they need good current regulation. Internally, they all have current limiting resistors unless they put all the LED's in series to get the proper voltage across each individual LED. I think some of the festoon bulbs do this. The problem is that the voltage source to the license plate bulbs is very dirty and effectively unregulated. It does not matter with regular bulb, but for LED's, it makes them wear out very fast.

One trick is to use a voltage regulator, like a 7805 (looks like a transistor) with a few resistors to limit the current. The only thing is the voltage needed for the LED strings needs to be less than 12 volts. This is makes it hard to modify for LED bulbs made for cars. Truck lights are design for automotive use and the LED is of a higher quality and some have active currently regulation. Although, some just have resistors.

For myself, I replaced my license plate illumination bulbs with tiny, fluorescent square lights. They were surplus and were made to back light some sore of display. They need a driver board, similiar to a cold cathode inverter to make them light up. They are brighter than bulbs and cast a white light. This is not a drop in solution. I had removed the piece above the license plate and removed the bulb assembiles, then I mounted the square displays in the rectangle holes and used black lexan to fill in the edges.

glassJAw

^^^
Great post. Thanks!!!

If I understood your post correctly, you need the 7805 to clean up the power supply and then the resistors to reduce the voltage to the bulbs to under 12 volts?? You can get these things at Radio Shack right?? Do you have any ideas how to wire them up??

rob_fed

Yes, parts can be found at Radio Shack. You can go here to see some circuits.

http://www.trainweb.org/girr/tips/ti..._led_tips.html

The problem is that if you are trying to control the current for the festoon bulbs, internally, they are wired to accept 12v-14v. If you use a 7805 or similiar, you will always need more input voltage to the regulator than what you trying to drive with the output. This is why the 7805 is useful for individual or small strings of LEDS. You can make the 7805 variable by not grounding the gnd pin. There is a voltage divider circuit that can do this, but again, you will need more input voltage than the output.

Search for voltage regulator and led for more web pages.