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Unread 12-02-2010, 07:55 AM   #1
jeepkid03
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A few questions on LEDs

Ok so I'm thinking of doing the LED dash mod and a search didn't really answer my questions... just came up with a bunch of people in TJs putting funky colored lights in their dash.

1. I know you have to order the right size bulbs for the dash and that you can put them in place of the old bulbs. I've been looking at LEDs from superbrightleds.com. I read somewhere that you need a resistor in order to make the LEDs last longer, otherwise they will be very short lived. Is this correct? Would I need to wire in some sort of resistors in the dash or are the LEDs basically plug and play? Can I just put them in place of the old bulbs with little to no modification?

2. I also have a top brake light out, and I see that the website lists LED bulbs that are direct replacements for the top and side rear bulbs. I know the blinkers need a different flasher setup otherwise they will blink too fast, so I only plan on doing the tail/brake lights. Would these be brighter or as bright as stock lights? LEDs are supposed to give the car behind you more reaction time to your brakelights since the light is more direct and reaches their eyes quicker, so thats why I'm interested.

If anyone who has had experience with LEDs could chime in that would be great.

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Unread 12-02-2010, 08:30 AM   #2
Natrik81
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LED's run on about 2 volts so you need a resistor that will throttle the 12 volts in your jeep down to the 2 it needs. I can't remember the exact one you need, I think it may be 700 ohms. You can find a calculator online to find out for sure. LED bulbs made specificlly for replacing marker lights and blinkers have resistors built in. You can get a load equalizer to make your blinkers work the way they should by adding a dummy load to your flasher relay.
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Unread 12-02-2010, 08:57 AM   #3
chriskeenan
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The led's drop into the place of the stock bulbs, its a 10 minute install, 15 minutes if you put some in backwards (the LED's are polarized), the bulbs are type 74 in the dash, you need 5 for the backlights. If you want to do the HVAC controls you will need 2-3 of the neo4 bulbs. The rear wipe-n-wash, heat grid, and fog light switches each take 1 neo3 bulb for the backlight and another separate one for the indicator if it has one. The backlights for the two shift bezels are both 194's and you may need to drill them out a little to fit the 6 led 194's inside them (if you get the 6 led ones, otherwise you might not need to drill). Also don't cheap out, get the 3 LED 74 bulbs to avoid dark spots and the brightest ones every where else.

There is no need for a resistor, most drop in led bulbs will have either a resistor built in or a buck driver (voltage regulator) in the assembly. If you went to radio shack and bought parts to make your own bulbs then you would need a resistor or buck driver to limit power to the led. Example; most component led's are rated to about 2.2-2.4vdc, they would last ~0.0023 seconds at 11.5-14.5vdc without a way to regulate the voltage down to 2.2vdc or less, a resistor is the cheap but effective way to do this, although a buck driver set up works much better and offers a wide operating voltage range with less power loss.

The thread you found with the TJ's is the same way to do the swap in a 97+ XJ.

I bought my all (~20) of my LED's from superbrightleds.com and have been very happy with them, 0 failures, 0 DOA's. I even got one of their little cigarette lighter/power outlet rechargeable LED flashlights, also highly recommended.

The tail lights I don't know if they are brighter but I would assume they are, the quicker illumination time (if IIRC, ~0.25 seconds quicker than incandescent) of the LED's doesn't make much of a difference at low speed but at highway speed it can give the person behind you about an extra 20ft to react.
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Unread 12-02-2010, 09:59 AM   #4
jeepkid03
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Thanks for the input that helps a lot to get the bulb numbers! Do you by chance have a pic of your dash with thr LEDs? How hard is it to put them into the HVAC controls and wiper switch? Those look like they are sealed off.
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Unread 12-02-2010, 10:23 AM   #5
jgale
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I'd love to see a picture also. I think amber in the inst. panel would be very cool.
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Unread 12-03-2010, 06:15 AM   #6
chriskeenan
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The LED's are the red tri-leds from superbrightleds.com, the odometer readout is still green, there's no easy way to change it, but aside from that it looks perfect, its much red-er in person, these are cellphone pic's.

Sorry for the bad photo here, but this is the HVAC and shifters, the HVAC controls are very dim due to the tinting built in to them, there's no way to fix this that i know of. The shifter bezels are quite bright (compared to the HVAC) but no so bright that it will blind you while driving or be a danger, it gives the cabin a very dim red glow.

The trans shifter has a colored plastic filter you'll need to remove and replace with some white paper. The switches look perfect though, rear wipe-n-wash is missing cause its broken.

To change the HVAC backlights simply un-bolt the switch assembly you don't need to disconnect any of the wires or vac lines, find the the bulb bases on the back side twist them 90 degrees and remove.
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Unread 12-03-2010, 06:42 AM   #7
jgale
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Very cool. Are the LEDs still dimable, or are they on/off?

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Unread 12-03-2010, 06:47 AM   #8
chriskeenan
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nope, no dimming, i never used the dimmer function to begin with. You would need a PWM (pulse width modulation) dimmer to dim them.
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Unread 12-03-2010, 08:30 AM   #9
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I like how that looks! You said that the dash LEDs were tri-LEDs. That would be my next question... On the website it shows some bulbs having more LEDs in them than others with the same base. Which ones should I get to have the brightest output while still making sure they fit in the housings correctly? Do you think brighter ones would solve the dim HVAC controls issue? Seems the website describes the bulbs with more LEDs to have a wider pattern like a filament bulb.
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Unread 12-03-2010, 08:59 AM   #10
chriskeenan
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Quote:
Originally Posted by jeepkid03 View Post
I like how that looks! You said that the dash LEDs were tri-LEDs. That would be my next question... On the website it shows some bulbs having more LEDs in them than others with the same base. Which ones should I get to have the brightest output while still making sure they fit in the housings correctly? Do you think brighter ones would solve the dim HVAC controls issue? Seems the website describes the bulbs with more LEDs to have a wider pattern like a filament bulb.
They will fit in the housing just fine, the photos on the website make them look much bigger than they really are, even the tri-leds are only 0.25in thick.

The wider beam pattern with more LED's is correct.

I have the NEOx series bulbs (the high powered ones) in the HVAC controls. Its not that the bulbs are to dim its the tinting. All LED's (even white ones) emit one color along a specific wavelength (red for example is 626 nm/k) the tinting on the HVAC controls is blue (and red in a few places for heat) so it filters out all light that isn't blue so you don't see much light coming out of it. Regular incandescent bulbs emit all colors so the tinting works fine for them.

My recommendations for bulbs are the 74-xHP3 series for the dash, and the NEOx series for the HVAC and switches, and then the WLED-xHP5 or the WLED-xHP6 for the shifters. I know the WLED-xHP5 i had to drill out the hole in the bezels a little bit for the bulb to fit inside, but the xHP6's look like they might fit better.
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Unread 12-03-2010, 11:20 AM   #11
Azzy
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Any good way to tell or test leds before you assemble the dash? Flashers and headlight bulbs are easy to test out... check engine light and stuff of that nature isnt.
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Unread 12-03-2010, 11:32 AM   #12
chriskeenan
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To test them in the dash you have to plug the cluster in to its "self-docking" connector, you can leave the trim bits off. If you choose the replace the indicator lights (CEL, high beam, part-time, seat belt, parking brake, ect.), just run the self test. To do this hold down the trip reset button and turn the key from the off to the run position, the cluster will then run through its self test, turning on various indicators and moving the gauge needles and will also show any OBD2 trouble codes in the odometer read out.

Video here: http://www.youtube.com/watch?v=mEeIuTWjdlg
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Unread 12-03-2010, 04:10 PM   #13
Azzy
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Will that work on a 96 with no digital trip?
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Unread 12-03-2010, 06:51 PM   #14
chriskeenan
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nope, on the per 96 XJ's its turn the key from off to on and back to off 5 times very rapidly, the ODB1 codes will be blinked out by the CEL light when the self test is done.
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Unread 12-03-2010, 07:08 PM   #15
XJdriver
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I did the same mod with blue LEDS


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