Posts Tagged ‘trouble shooting’

How To: Test The Polarity Of V-LEDS

Posted: February 4, 2011 in How to:, Technical, Trouble Shooting
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My last post was on how to make a quick and easy test light. This is a little trick you can use to test your LEDs. Use this to verify which contact on your LED is the positive and the negative. If you think you have a defective LED you can use this to confirm if it’s the LED that’s not working or if your cars socket is the problem. Items needed to make this tester include a fresh 9 Volt Battery, a couple of lengths of wire and some electrical tape. This is easy to do, lets cover the steps.

Look at the picture below. Start out with your wire, tape and battery. Strip some sheathing off of both ends of the wire. Fold back the wire on one end. Note the positive and negative terminal of the battery and place the wire on top of each terminal. Fold the tape over and use it to hold the wire onto the terminals of the battery. And you’re done!  To use this new tool just touch the bare wires from picture #4 to the contacts of the LED, note which wire is positive and negative. If the LED  lights up you have the polarity correct. If the LED does not light up, reverse the wires and try again. If it still doesn’t light up than either the battery is dead or the LED is not working.

This little battery tester has helped me in may different ways. If you do not have a 9 volt battery, any battery will do. I have done this with power tool batteries too, just don’t use any batteries larger than 12 volts. You can use this for more than just testing LED lights. I first used this setup to test for speakers in cars when the radio harness was cut off. After I located all of the power wires I would use this to test the remaining wires to match up the pairs of speaker wires. And you can see the speaker move in or out too, which tells you what speaker wires are positive and negative.

I have had people ask me if you can get shocked by touching both wires at the same time, the answer is no. It is very rare that you would get shocked by 12 volts DC power; it is possible, but you would have to be trying really hard.

Thanks for reading. If you have another use for this type of tester of if you have another invention that you use on a regular basis please share. You can email me direct at: tech@v-leds.com or leave a comment below.

James, the tech@v-leds.com.

How To: Make A Test Light Using An Automotive Bulb

Posted: February 2, 2011 in How to:, Technical, Trouble Shooting
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Have you ever needed to troubleshoot a problem with your electrical system and there is not a test light around? Do you have a little MacGyver in you? If so than this quick little invention can be a lifesaver if you’re stuck in the woods or the local auto parts store is closed and you need to get some work done. If you are working on your car you most likely have the necessary items laying in front of you. If you’re like me you usually have random tools and supplies hiding under the seat from the last time you worked on your car. Regardless, the only things you need to build this test light are a couple short lengths of wire, a dome light bulb  and  some electrical tape. (If you are in a bind you can use any bulb from your car and any tape will work)

The steps are easy. 1) Locate all the necessary items. 2) Strip 2 Inches of the sheathing off of the wires. 3) Wrap the bare wires around each end of the bulb. 4) Tape the wires in place and strip about 1/2″ of sheathing from the other end of the wire.

This thing is pretty simple to use. If you need to find +12 volts just hold one of the wires to ground and touch the other wire to the circuit that needs testing. If the light turns on you have power.

If you need to find a ground you can hold one wire to +12 volts and touch the other wire to ground. If the light turns on you have power.

Hopefully you remember this when you need it most. Or you could just buy a test light and keep it in your car just in case.

Thanks for reading. Be sure to share this with your friends, you never know who might be in need of a test light.

James the tech@v-leds.com

When I Step On My Brakes My Dash Lights Dim Or My Parking Lights Turn On, WHY?

Posted: November 19, 2010 in How to:, Technical, Trouble Shooting
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I have been fielding this question more and more lately. I experienced this problem first hand before I worked here at V-LEDS. I diagnosed the cause of the problem and then I was able to come up with a solution to fix it. Lets find out the cause first.

My experience was stumbled upon after the car I worked on left the shop. The customer called back a short time later and stated that he noticed something weird when he was parking in his garage. When he stepped on the brakes he noticed that the white LEDs that were installed up front were lighting up at the same time. I did not know how to explain this, this was my first time using any products from V-LEDS. I then contacted V-LEDs and asked if anyone had seen or heard of this happening before. At the time they had not. (this was about 3 years ago) So I asked the customer to bring his car back to the shop and leave it with me so I could try to fix the problem. I figured that the source of this problem was the brake lights, because it happened when the brakes were pressed. This particular car, a 2007 Shelby GT 500 uses 3 pair of lights for the tail-lights/brake lights. I used the best of best from V-LEDS, and had installed 3 pair of the 3157_92_R LEDs. Up front I had installed the 3157_60_SMT_WA1_6K. What I noticed was this:  when the parking lights are in the off position the white LEDs on the switchbacks would come on at about half power when the brake lights were on. I removed the taillights and grabbed my DMM (digital multi meter) electrical tester and got to work. The condensed edition of what I found is this: With the Parking Lights off and the Brakes lights on about 5 volts would show up on the parking light circuit. I reinstalled the original filament bulbs and the problem went away. So I concluded that the LEDs were causing the issues. I didn’t think much more at the time other than that it needed to get fixed so the customer could have his car back. I had plenty of electrical components in my shop and went straight for the diodes. I figured i could use a 2 amp diode to keep the +voltage from back feeding into the cars parking light circuit. I installed 6 diodes, 1 for each brake/parking light and it fixed the problem.

This all happened a few years back. Now that it is my full time job to help customers of V-LEDS find solutions for problems that can occur from replacing filament bulbs with LEDs I have seen other variations of this same problem. These include, when the brake lights are on: the dash lights dim, the navigation or radio display dims, and the fog lights come on. Some of you just want to know how to fix it, but others are interested in WHY it is happening in the first place. So I would like to take the time to explain why. Here goes…

There is an electrical component on a circuit board inside the LED bulbs. This component is responsible for the output brightness of the LEDs on the bulb. This means that the LEDs are being run at half power when the parking lights are on, and full power when the brake lights are on. This is how our LEDs differ from a filament bulb. In filament bulb there are 2 separate filaments, a low filament and a high filament. They are not connected internally and they both operate at full 12 volts. Each of the 2 filaments are of different wattage. This is how a dual intensity filament bulb works.

In the pictures below there is a diagram showing how to install the diode inline on the parking light circuit and an illustration that explains how a filament bulb works compared to an LED bulb.It also shows how the voltage back-feed happens.

This diagram shows how to install the diode inline to fix the problem

This illustration shows how a filament bulb works VS an LED replacement bulb.

If you have any more questions about this or if you are experiencing similar problems feel free to contact me via email here:  tech@v-leds.com, and I can give you a hand.

Thanks for taking the time to read through this article, I hope it helped you out.

James, the tech@v-leds.com

Polarity and V-LEDS

Posted: November 11, 2010 in Trouble Shooting
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I’m sure you already know that LEDs are polarity sensitive. If you didn’t know this basically means that they will not light up if the power and ground are connected backwards. So if you plug in you new V-LEDS and they do not light up, try flipping them around and plugging them back in and they should work. I want to go over some other polarity issues where flipping the connection over will not work.

Here is the classic example. Your car, truck, or motorcycle uses an 1156 style bulb and you have replaced your blinker or brake light and it won’t light up. The filament bulb that was installed before worked just fine, why is the LED not working? Simple answer is polarity. The problem here is that you can’t just flip this bulb around to make it work. The metal base is the main contact and there is a center pin in the bottom of the socket that is the other contact. The problem here is associated with the wiring on your car. The wires going to the socket are backwards. The industry standard is the metal base is the ground connection and the center pin is the power connection. Some car makers do it differently and use the metal base as the power connection and center pin as the ground connection. Why? Not too sure but it is easily fixable if you have some tools. You will simply need to cut the 2 wires routed to the plug and reconnect them backwards. Solder and heat-shrink the connections if you have the a soldering iron, otherwise a simple, crimpable, butt connector will do the trick. I have found on some cars this is not possible, usually European cars with one piece buss bar socket setups like the picture shown. You cannot modify the wiring for these sockets as all the bulbs share a common ground wire or common power supply. If you find that your car has this type of tail light assembly I highly recommend testing it with a test light to see if it is wired backwards before you purchase any LEDs.

Another polarity issue that can be a problem is on some blinker circuits. Known vehicles are the newer Jeep Grand Cherokee and Wrangler and some GM trucks and SUVs. These vehicles have a 194 sidemarker bulb that also acts like a blinker. When the parking lights are in the OFF position this bulb is off. Once you turn on your turn signals this bulb flashes on alternately of the front blinker. When the parking lights are in the ON position this bulb is on. Once you turn on your turn signals this bulb flashes off alternately of the front blinker. This is a series circuit that is fed power from 2 sides. It requires that voltage and ground be able to flow both directions through the filament of the 194 bulb. Once you replace this bulb with an LED the power cannot flow through and will cause the blinker to stop working. We have some 194 LEDs with special circuitry that will work for this application, but they are Flank style LEDs and usually do not work for this light housing application (light is shining the wrong direction).

So if you find that you are experiencing one of these problems grab a test light and test your sockets. Or put the filament bulb back in and see if everything is working.

Thanks for reading. Feel free to leave a comment or ask questions. You can leave them here or email them to me directly here: tech@v-leds.com

James the tech@v-leds.com