LED Headlamp Install

3p141592654

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#1
Installed some generic Amazon 5x7 LED headlamps. These headlamps are polarity sensitive like most LEDs (except the Trucklites) so you need to convert to a switched positive setup.
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I used a pair of "polarity converters" bought off of Ebay. Search for "2X H4 Positive and Negative Converter". You can do the same with a SPDT relay if you know how, but I was lazy and didn't want to source all the connector parts. They were $30 for the pair, and one was DOA and I am still trying to get it returned and resolved.
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I would suggest hooking all the parts up loose and verifying functionality before securing it all down into the car.

I bolted the converters to the plastic frame in the back of the lamp bezel. This allowed me to reuse the existing harness which is important because the harness flexes when the lamps go up and down and Toyota was careful to minimize the chance of the wires breaking after many up/down cycles. The LED lamps are much thinner than the original halogens, so there is plenty of room behind the light for all the connectors and converter crap.

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The converters requires an extra ground wire. I ran that wire in the same corrugated plastic flex tubing as the factory wires then exited the flex and connected it to the existing front turn signal light harness ground wire that runs inside the frame there. This was the most annoying part because access to the wires is tight. I pulled the turn signal light assembly out to help get my fingers in there. I didn't use the provided eylet for the grounds as the wire was way too short and I didn't think it would hold up too long given the wet nasty environment near the lights. The lamp bezel is not well grounded so don't try to hook it up to the metal lamp frame.

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I am pretty happy with the results. The lights replace previous Cibie E-code halogens which are about as good as you can get pattern wise for halogens. The LEDs perform about the same on high beam distance wise, but the light is whiter and the foreground illumination is much better. On low-beams the foreground is better illuminated, and the the beam is much wider, but the cutoff is not as pronounced as the halogens. Overall I am very happy with the results.

The one downside is the high beam panel light no longer works. I think I have a fix and will update when I get it sorted out.
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plaaya69

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#2
Nice write up 3p. I ditched aftermarket HID's along time ago with all the problems I have had in the past and been rocking the stock halogen headlights (they might still be original lol) for sometime. With LED technology improving, I definitively think a modern LED headlight upgrade will be in the near future...

Are you running LED's in the fog lights also?
 

3p141592654

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#3
Yes, I replaced the H3 halogens with some H3 LEDs. I recently updated them as I have had probably 5 generations of LEDs in the last decade in the fogs. The early ones were absolutely terrible, barely any light but they worked well as DRLs which was my main goal. The most recent ones are definitely getting closer to the H3 halogens in light output. Still inferior, but much better.

I got these ones from Amazon for I think it was $22.

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3p141592654

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#5
So I have got the high beam indicator light to operate normally using the stock wiring and the polarity converters.
The high beam indicator is a #194 bulb in the instrument panel that is normally powered though the low beam filament of the headlight. This requires about 300mA of current to light the bulb.
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When the LED headlamps are installed, with the polarity converters, the most you can get through the low beam circuit is about 35mA, not enough to light the original indicator bulb anymore.

The trick is to replace the #194 bulb with a blue LED #194 version, and setup the LED bulb for about 5-10 mA of current. The bulb is plenty bright enough at that current for the panel indicator.

I've had terrible reliability with purchased #194 and #74 small LED bulbs (ebay amazon, superbright, etc). So I make my own now with quality parts from Mouser or digikey.

To set the bias you need a series 0.25 Watt resistor with the LED, and the following values are generally good for the indicated current.
5.6kohm 2mA
2.4kohm 5mA
1.2kohm 10mA
620 ohm 20mA

In my case, I took a commercial #194 blue LED bulb and I replaced the 360ohm resistor (about 35mA) with a 2.4kohm resistor (metal film). I measured about 4 mA after I soldered it together as shown below. The lower current should give much better reliability than the original value of 35mA, and you just don't need that much brightness for the panel light anyway.

Here is the original #194 led bulb pulled apart
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I desoldered the original resistor and replaced it with the 0.25W 2.4kohm metal film resistor from Mouser.
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The I stuffed it back into the original plastic LED package
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tested it to make sure all was good and the current was correct
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then I pulled out the panel and replaced the original bulb with the modified LED bulb. Tested it before I put the panel back in and all worked perfectly. Note that if you insert the bulb and it does not work, you need to rotate it 180 degrees because it is polarity sensitive. So do this before you put the panel back together.
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3p141592654

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#6
Since I had the instrument panel out, I also took the opportunity to replace the instrument panel clear plastic cover. I bought this years ago and it has sat in my garage for a long time. It is amazing how cloudy and scratched the original cover was, With the new one in place its like getting into the car 30 years ago when it was brand new. It is really amazing the difference.
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Old Radar

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#8
This thread immediately reminded me of this:

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I wanted to insert the clip from Star Trek: The Motion Picture, but didn't have the tools to edit it down to just this blip.
Ouch! Kind of the story of my Supra modding efforts...
 

3p141592654

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#11
You can polish the old plastic cover and sell if you really want to, or keep it for a back up.
That's a good point. But my old panel has a crack in the black plastic by the center vents. The other thing I'll say is that the black textured plastic also looses its lustre over the years, and the new cover fixes that too.