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Led Stop/tail Lamps/bulbs


wwest
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The red enclosure at the center of the picture is the bulb/lamp failure sensor mounted in the trunk of my '95 LS400.

There are three separate failure circuits, stop lights, tail lights. and high mount stop light, all driving one indicator lamp on the combination meter assembly.

The circuits use nichrome resistive links and if you wish you can substitute empirically determined resistor values once you know how much current each LED "group" will draw. But be aware that dual brightness, dual function LSD lamps do not draw current flow on the low light side when the high side is powered. In my '01 RX300 I added a transistor switch circuit inside the enclosure to simulate the current draw of the LED tail lamps when the stop lamp section is powered.

But since the reliability of LED lamps is head and shoulders over incandescents that was way too much trouble for what it was worth.

So this time I just clipped/opened the violet/green wire going to pin #4, the output driver to the instrument panel rear bulb failure icon.

From top/left in the picture the connector is numbered:

-5--4---------3-2-1

12-11-10-9-8-7-6

post-4016-1202595268_thumb.jpg

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Now that is good thinking. I was going to do the same when i finally find a set of smd bulbs bright enough to echo in lumens a halogen bulb. So far the smd's might be "1 watt" but they are still too dim for my tastes to feel safe using them.

What bulbs are you going with?

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Now that is good thinking. I was going to do the same when i finally find a set of smd bulbs bright enough to echo in lumens a halogen bulb. So far the smd's might be "1 watt" but they are still too dim for my tastes to feel safe using them.

What bulbs are you going with?

Stop/tail:

http://www.v-leds.com/Shop/Control/Product...sid/0/SFV/32481

Turn (REAR):

http://www.v-leds.com/Shop/Control/Product...sid/0/SFV/32481

In a visual comparison, one side with LED the other with the OEM incandescents, these appeared to me to be just a tad brighter.

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So do the "SMT LEDs" still require resistors??????? Why can't they just make an LED buld with a built in resistor?

There are two resistor "issues". One is a voltage dropping resistor so the LEDs will operate at the correct voltage/current rating, typically 3 to 4 volts. Those are almost always, if not always, included in the base of the standard LED bulb replacement. So a 7443 LED bulb simply plugs into a 7443 incandescent bulb socket.

The second issue is a bit more complex, moreso with a Lexus since they always have bulb failure sensors.

But the first thing is to "tackle" the turn signal flasher issue. In many cases you can simply buy an electronic flasher which is NOT sensitive to the electrical current load represented by the incandescent bulb filament. For turn signal bulbs that is typically 1.80 amps at 12 volts, 3.6 amps for both to a side.

The amber turn signal LED lamps that I chose, 7443 for the rear and 1156 for the front, each require 0.120 amps, 0.240 amps total per side.

Other than buying an aftermarket solid state flasher relay some people choose to simply add resistors in parallel with the new LED bulbs. In my case that would have required two ~4 ohm resistors with a minumum power rating of 20 watts. The turn signal duty cycle is only ~50% so a 40 watt resistor is not really necessary. Obviously incorporating a 20 watt resistor within a LED lamp is out of the question.

With the Lexus there is also the issue of disabling, or modifying the bulb/lamp failure sensor.

I disabled the one in my '95 LS by opening the circuit to the bulb failure "icon" lamp.

Also remember that many newer cars, like the Lexus, come with an electronic flasher relay that has an integral "fash flash" bulb failure sensor to let the driver know that a turn signal bulb has failed. With two bulbs, or 4 in hazard mode, it flashes at the normal rate, with only one bulb in the circuit in turn signal mode it switches to fast flash as an indication of the failure.

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Oops...

Almost forgot.

I opened the "tail" light circuit to the "inside" 7443's, the ones in the trunk lid, so as to give a much more "pronounced" indication, beyond just the high mount, that I have applied, am currently on, the brakes.

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