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Old 03-11-2013, 02:46 PM   #1
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Join Date: Aug 2012
Location: Vancouver, BC
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DIY Flicker Harness

Hey all,
I know this is a big deal for those of us with the Trucklite or JW Speaker LED Headlights, so I thought I'd do a write up on how I solved the flicker issue on mine. Personally, I didn't notice any flicker with the low-beams on at night, but in Canada we are required to have daytime running lights by law, and the CANBUS kicks the voltage down to half of the norm on the low beams for that. It causes major, siezure-inducing flicker, to say the least, and it annoyed the living hell out of me.
This is the write-up I used to build my headlight harness, so all kudos go to Venom on the other forum for this:
Headlight harness how-to - JKowners.com : Jeep Wrangler JK Forum
Anyhow, some backstory:
Why Your LED Headlights Flicker
Basically, the power to your headlights goes through the Jeep computer, which modulates the strength of this feed. With conventional headlights, a variety of voltages isn't a problem, as with a lower voltage they dim a little and a higher voltage they get a little brighter. LED's are a different story: In layman's terms, with lower voltages, LEDs aren't supplied with enough voltage to keep running at full power, thus, they flicker.
How to Fix It
There are a few ways to go about it. The simplest is to buy the Susquenna Motorsports (Spelling?) Harness. The cheapest is to build that exact harness. Both work the same way in that they take the signal from the Jeep computer, but not the power, which is supplied directly from the battery. So basically, the Jeep computer still operates the headlights (and more importantly thinks it operates the headlights), but doesn't supply any power to it. This is what I did.
Some things you'll need:
- 2x 30-40A 12V Relays
- 2x 100uF 35V Electrolytic Capacitors (or 220 pF)
- 2x 1N4001 Diodes
- 1x 40A fuse and fuse block
- Various wires, connectors, shrink wrap, pliers, etc.
Now, I'd like to just say off the bat that this is NOT difficult to do, but does involve some patience. I'm decent with electrical stuff, and it took me a solid 3 hours to build it from scratch. That said, the instructions I had were fairly limited, so it took some thinking. I'd say that this will take between 2 to 4 hours, depending on how experienced you are.
Now, the wiring diagram:
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This can definitely seem confusing, so I'll try to simplify it as much as possible.
1. The symbol in the top left corner is the battery. You'll be running a wire from the positive terminal of your battery to your headlight relays.
2. The 'Jeep Side Connector' is the connector on your headlights that comes from the Jeep (and Jeep's computer). There are three wires coming out of it: Hi-beam, lo-beam, and ground.
3. Conversely, there are three wires coming out of your headlights; hi-beam, lo-beam and ground.
4. Relays: A relay is like an intelligent switch. It has four different ports on it, numbered 30, 85, 86, and 87. 30 is where your direct power from your headlights go, 85 is where your headlight signal goes from the Jeep, 86 is where your ground goes, and 87 is the output power to the headlights.
5. The capacitor goes between your headlight signal wire and your ground. This smooths out the power that is supplied by the computer, which eliminates the flicker. I personally used a 100uF capacitor, but I did notice a slight delay going between hi and lo beam, so it may be better to use a 220 pF capacitor as this might eliminate that.
6. The diodes go on the headlight signal wire from the Jeep connector. This just protects the computer as the diodes only allow current to flow one way.
Without further ado, the steps necessary. READ THIS MORE THAN ONCE BEFORE YOU START CUTTING THINGS APART:
1. Run a wire from the positive terminal of your battery to your driver's side headlight. Place a 40A fuse within a few inches of your battery to protect all the fancy electrical equipment you're about to add to your Jeep. It's a good idea to take the fuse out for the duration of this install so you don't electrocute yourself. Also, make sure you use 12AWG wire for this, it's a pretty hi-power application and a long run.
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2. Split the direct power wire somewhere near the headlight.
3. Cut your Jeep side connector off, leave like 3" or so. The ground wire needs to be split, and the hi-beam and lo-beam power need to have diodes wired to them. Use 16-18AWG wire.
4. Wire up the capacitors. The way I did it was to use a butt connector, and a red wire to the positive terminal, and a butt connector and a white wire to the negative terminal.
5. Get three good lengths of wire (1.25 m or 4' or so). If you can get red, green, and white, it may make your life a lot easier in the long run. Run these from your passenger's headlight to your driver's headlight.
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6. Finally connect everything together with the relays. You'll need the ground and the negative terminal of the capacitor going to 86 on your relay; the signal from the Jeep connector and the positive terminal of the capacitor going to 85; the direct power from the battery going to 30...
7. ...and the headlight power going from 87 to your headlights. Cut the Jeep side connector on your passenger's side and connect that long run of wire from the last step to that headlight, and the existing headlight wire on your driver's side gets put together with the run from the other side and wired to the capacitor. (Apologies about the image quality).
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8. You'll have to do steps 6 and 7 twice as you have two relays to do, one for hi and one for lo beam. It doesn't really matter which is which, just MAKE SURE that the color going into terminal 85 is the same as the color coming out of terminal 87 on the relay. This is why it's nice to have the wires color coded for step 5.
9. Finally, squish all that new wiring in, put the fuse from step one back in, bolt your headlights back up, and test it out! Everything should look excellent and your lights should be bright as hell, without flicker. Also, you may need to adjust your headlights, mine got thrown all out of alignment when I did this. See this: TECH TIP : Jeep JK Wrangler Headlight Adjustment

Have fun guys, and I hope this helps. If my instructions and the wiring diagram differ at all, the wiring diagram supercedes anything I have to say.

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Old 03-11-2013, 10:10 PM   #2
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And, just as a lovely heads up to those Canadian JK owners, the Daytime Running Lights are actually the high-beams at half power. So, when you do this upgrade you'll be rolling around with full-power high-beams on unless you have a ProCal to change it (I learned this after I did it). But it does most definitely eliminate the flicker, and make your lights insane bright.

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Old 03-12-2013, 10:30 AM   #3
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Please indicate the color / stripe on each of the 3 wires coming out of the "Jeep side Connector" for high / low / ground that create the control circuit to your relays. Which is which? Yes, I can check but since you already did it, that would save a step )as well as not screwing up the grounding).

Did you pickup the diodes & relays at Radio shack or another source?

It looks like the light is acting as the resistor in the circuit - I was wondering whether another in-line resistor was going to be required (proposed by a EE friend) but it looks like it won't. Good to know.

Did you wire it up as a "black box" or leave the relays & capacitor exposed?

Thanks.
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Old 03-14-2013, 05:27 PM   #4
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I'd have to snatch my headlights out of the Jeep again to check, but if I remember correctly, the wires I had were green for Hi, red for Lo and white for Ground. Keep in mind though, I used the supplied Truck-lite connector to butcher instead of the stock one as I didn't want to mess with the stock harness. Might be best to take your multi-meter and get a reading on which wires do and don't get power when you turn your hi-beams -- the one with power all of the time is lo, the one with switch power is high and the other is ground. That's what I did =).

I've heard that people in the States can get all of these components at Radio-Shack, but in Canada Radio-Shack was bought out years ago by Circuit City and now is this tiny, terrible gadget store. I ordered all of mine through DigiKey Electronics - Electronic Components Distributor.

So far I've left them exposed, but I'll probably wrap them up in some tape/convoluted tubing at some point in the near future. There's not a ton of room to play with back there so I think a box is probably out of the question unless you ran the wires to the other side of the WW fluid container.
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Old 04-05-2013, 10:10 PM   #5
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great tip used the 220 capacitors no delay in activating the high beams no more flicker
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Old 04-05-2013, 10:49 PM   #6
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My Truck-lites have a noticeable flickr with the high and low beams. I will be going the additional harness route. I love the wide pattern of the LEDs, especially on back country roads, but need to eliminate the flicker.
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Old 06-08-2013, 04:24 PM   #7
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Quote:
Originally Posted by stuggin View Post
I'd have to snatch my headlights out of the Jeep again to check, but if I remember correctly, the wires I had were green for Hi, red for Lo and white for Ground. Keep in mind though, I used the supplied Truck-lite connector to butcher instead of the stock one as I didn't want to mess with the stock harness. Might be best to take your multi-meter and get a reading on which wires do and don't get power when you turn your hi-beams -- the one with power all of the time is lo, the one with switch power is high and the other is ground. That's what I did =).

I've heard that people in the States can get all of these components at Radio-Shack, but in Canada Radio-Shack was bought out years ago by Circuit City and now is this tiny, terrible gadget store. I ordered all of mine through DigiKey Electronics - Electronic Components Distributor.

So far I've left them exposed, but I'll probably wrap them up in some tape/convoluted tubing at some point in the near future. There's not a ton of room to play with back there so I think a box is probably out of the question unless you ran the wires to the other side of the WW fluid container.
Stuggin: What part # did you order for the capacitor? I am wanting to go the 220pf capacitor route also. Do you have part #'s for the rest of the components that you ordered on digikey?
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Old 07-18-2013, 10:30 PM   #8
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So you are just using the one jeep side connecter to trigger the lights right?
The other side isn't used at all?

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