90Conv

Has anyone had experience with replacing your directional bulbs with LED's? I replaced my 3rd brake light and rear tail/stop with LED bulbs. I also replaced the flasher with an electronic one. They worked great. i purchase the same bulbs but in amber for the front parking/directionals. This where it went sour. Th efront bulbs hardly light and the directionals no longer work. If I go back to original bulbs up front then all is well. Has any body had the same experience and figured out how to fix it? I did the same thing to my 1996 Impala SS and had the same results. Any help would be appreciated. THANKS

TeknoMaeg

That's bizarre... Impulse says that the new bulbs are draining your electrical system. But then again, LED's use less power. SOOO...

Without running a voltmeter on your car... not sure how to help.

mechguy79

Is there some kind of resistance difference? Do the LED's require a higher voltage? Amperage?

TeknoMaeg

LEDs general require less of both. That is their allure. Due to their design they are SUPPOSED to use less voltage and require less amperage to light.

Granted. That's if the bulb-LED swap was the same watts. Which may be your problem. These LEDs may just be super bright and may be asking too much of yuor relays.

mechguy79

Well if the wattage was too high I would worry about the wiring AND the relays. I read a while back about some folks melting their headlight wiring and connectors putting those crazy bright headlights in older cars that didn't some with them. I wonder if that would happen here too.

TeknoMaeg

usually the relays would overheat or the fuse would pop. Not sure how they melted the wiring unless one of the two wasn't working properly.

Churchkey

Dim LED's--Sounds like a ground problem. Try running a test lead as an external ground if they plug into the original sockets or if they are a prewired board try switcing the wires.

Installing H4 headlights in older cars can be a problem. A standard H4 requires almost twice the amperage to run than the original headlights. Using the stock wiring will cause the headlight switch circuit breaker to cycle which = blinking headlights & overheated wires. The upgrade to H4's should include a separate circuit breaker to power relays for both high & low beam.

the blur

LED's are very picky about being grounded correctly.

LED's can't use "less voltage" as someone said.
Voltage is applied, not used. what ever the alternator puts out is the voltage applied.
The current draw is what changes.

The LED's or regular bulbs are designed to light properly at 12 volts. Actually a voltage range probably from 11 volts to 15volts.

Sliding

The problem is most likely in too low resistance that LEDs have.
You could try to put resistor in series with LEDs, or
check this:

http://www.eautoworks.com/product-Led-33226.htm

engle1147

I agree LED due to the nature of LED there is almost a dead short accross the LED light it's self so you need to use a resistor (~150 OHM)in series in the circuit for each bulb to make it match/act more like a regular bulb. LED bulbs that are installed with out a resitor will be really really bright because they are being "over driven".....and the LED won't last long like that so a resistor must be added. The more resistance (resistor) you add the dimmer the LED will apprear.

the blur

You need to re-read the instructions that come with that resistor kit.
It says place in PARELLEL, not SERIES. This is because LED's have a HIGHER resistance than incandesant bulbs. So this kit lowers the resistance when placed in parellel. Anyway, this kit won't solve his problem. The kit is for a "bulb out" indicator on the dash. C4's don't have that technology.

Sliding

You're wrong. The resistor should be in series.

Like this:

the blur

http://www.tuneshops.org/index~metho...icle_id~71.cfm

the above is the instructions that come with the kit YOU recommened.
It clearly shows the resistor in PARELLEL.
That kit will do NOTHING for his problems.

The LED bulbs he's using have a built in resistor, otherwise the LED's would burn out immediately.

Your method will cut the voltage to the LED bulb, and they'll light very dimly... if they light at all.

I have my masters in EE, while you are obviously still experimenting.

Sliding

I bought LED bulbs without internal resistor, and they didn't burn out
immediately. Problem that occured was too rapid blinking of corner light.
In series resistor took care of that. (This wasn't on my vette).

Here is a C/P from my link:
Since LED bulbs draw much less current then standard incandescent bulbs your electrical computer system may think that your bulbs are not working. This is a 6 Ohms 50 Watt resistor that needs to be installed in-line with your tail/blinker lights, one Load resistor is required for each tail/blinker light.

Doesn't in-line mean in series?

larryfs

I just looked at 1157 LED bulb replacements that I have in the garage. There most certainly is a resistor built into the little light capsule. Actually these have 2 resistors. I brought them in pep boys last week.
The store brought LED's are direct replacements for 1157's, and come complete. all LED's need a resistor designed in the circuit, or they fail instantly.

Go to radio shack, and buy a LED. Place it across your battery, and see how long it last. (where your saftey glasses )

This is basic electronics.

Sliding

Yes, and basic electronics says that you need resistor in series, doesn't it?

Maybe in USA all LED bulbs come with resistors, but I'm telling you what
situation I had. I bought LED bulb and it had NO internal resistor.

Here is very simple formula how you can calculate what resistor you need,
but you need to know LED's voltage and current ratings.

R=(Us-Ul)/I

where
R= resistance
Us= supply voltage
Ul= LED voltage (depends on LED type and colour, usually 1.5-3.5V)
I= LED curent rating (usually 15-25 mA)

I don't have masters in EE, but I am electronics technitian and have been
working in electronics for almost 13 years, so I know what "Ohms law" is.
And that is basic electronics, isn't it?!

jfb

Not in this case. The 6 ohm resistor insures that the turn signal lamp draws about the same current as the incandescent lamp does. This requires a parallel connection across the lamp socket. The flasher works on current, low current, low flashing rate or no flashing. Replacement LED lamps have built in resistors to limit the current to a safe value for the LED's in the lamp. LED replacement turn/stop lamps draw too small current by themselves to operate the flasher. The advantage to LED replacement lamps is a very long life.

the blur

The symbol for Voltage is "V", not "U".

You post a link for a resistor kit, but you still havn't read the instructions that come with the kit.

Yes, ALL LED's need a resistor in series, and they come built into the bulb package. No other way around it, or the LED's wouldn't last 2 seconds.

The kit YOU recommended is another resistor designed to be put in parellel with the LED bulb to INCREASE current draw. That's why it says it gives off HEAT, do not mount near plastic.

JFB got it right.

90Conv

Thanks for all of the responses. The bulbs i bought have built in resistors. As I mentioned they worked fine on the rear of the car. The problem came in when I tried to swap out the front turn and parking light bulbs. I would have thought that the bulbs with the built in resistors would behave like a regular bulb. obviously there is something different about the from turn signals. As I mentioned the same problem exist when i tried to replace the front bulbs on my 96 Impala SS. I am very confused by it...Thanks again

Sliding

I agree, if LED bulbs have internal resistor, than parallel resistor makes
sense, but for normal LED's it doesn't.

Please have in mind that I live in Croatia, an allthough electronics
basics are the same everywhere, LED bulbs that you buy here obviously
aren't the same.

And symbol for voltage is "U" in Croatia as is in some other European countries.

Ohms law (US):
http://en.wikipedia.org/wiki/Ohm's_law

Ohms law (croatian):
http://hr.wikipedia.org/wiki/Ohmov_zakon

I know that this is US forum, but sorry, I'm used to use Croatian symbols.