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jdeitch

Headlight basics: An enlightening discussion

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Not sure of those particular LED's. There are multiple 7" LED headlights for sale on Amazon and Ebay. Thank goodness there are so many Jeeps and Harleys out there so we can benefit.

If you can tolerate some of the Darth Vader looking lenses, wattage of some of the complete PAR bulb replacements (sealed units) run between 30 watts to 75 watts max. If you do some research will will notice some are more efficient than others, higher wattage does not necessarily mean higher lumen output. With some, you can get pretty good output with only 30 to 40 watt draw on high beams. Most are plug and play, and you don't need the funky CANBUS harness attachments that come with them.

Also be aware a good number of them are not DOT approved for road use. The prices are much less stratospheric than they used to be. Some are now going for about $150 a pair on Ebay.

Cheers.

Not sure what you're saying here...

I have tried multiple housing and I recommend these.

I have tried two different LED H4 replacement bulbs and I can recommend these LED bulbs.

These ARE lower wattage bulbs. 30 watts.

No external CANBUS or ballast module required. Literally plug-and-play.

Sent from my iPhone using Tapatalk

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Not sure what you're saying here...

I have tried multiple housing and I recommend these.

I have tried two different LED H4 replacement bulbs and I can recommend these LED bulbs.

These ARE lower wattage bulbs. 30 watts.

No external CANBUS or ballast module required. Literally plug-and-play.

Sent from my iPhone using Tapatalk

Sorry I wasn't clear. 

 

I just wanted to mention that there are PAR type LED headlights available as well for those that do not wish to purchase an H4 housing and LED bulb. 

 

Thank you for your blog it is very helpful. 

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Need some expert help. 

Have a (very stock) US 1974 2002tii.

Wanted to do the aforementioned swap out of my halogen H4's for the very same "plug&play" LEDs.

 

I "plugged", but got no play. So started trouble shooting.

·        Everything was working fine (and continues to do so) with the halogens. No bad wires, no bad fuses, no bad switches, or other obvious stuff. Even took out any potentially confounding fog-lamp circuit/relay to be sure.

·        I "bench tested" the LEDs and they work fine. If you directly apply 12V to them, ground+low beam terminals you get illumination of the "tip" LEDs. If you directly apply 12V to them, ground+high beam terminals you get illumination of the "base" LEDs.

·        So far so good.

·        When I place the LEDs into the car here's what happens: As soon as ignition power comes on, ONE (in my case passenger) LED glows a bit. Keep in mind, this is BEFORE switching on low-beams

·        When I switch on low-beams, either nothing happens, of both low beams come on with a flicker.

·        When I switch on the high-beams, they both work fine...but won't shut of when I switch back to low-beam...have to shut the ignition off.

·        One more tid bit before I give you my explanation. If you do a combination (one LED, one halogen) everything works fine again!

OK, so what's up? Here's my take:

I drew out the circuit based on the BMW wiring diagram (see enclosed jpg).

If you know about relays, the way BMW set this up is strange...but entirely consistent with the problem I'm having.

 

Normal operation:

1) When you turn on the car, current flows from the ignition to low relay in terminal 86 and out 85 to "close" the relay.

2) Low lights don't come on (even though the relay is closed) till you use the light switch to allow current to flow in to terminal 30 and out 87 to the halogen-low.

3) If/when you activate the High-beams via steering column switch, then lows go off and High relay closes with current in to 86 and out 85 to ground; power goes in 30 and out 87 to the halogen-high.

 

With LED bulbs:

1) Since terminal 85 in relay is not actually connected to ground (traditional use), the full current from ignition flows to ground to close the low-relay by using the halogen high filament as a resistor.

LEDs don't allow this so two things happen: a) LED in the path of least resistance show a trickle of light (they don't need much power to do this), and B) the low relay never really closes properly so when you try to turn on the low-beams you get a flicker at best. Totally consistent with what I observe.

2) When you activate high-beams, that works fine since that relay IS actually connected ground. But it doesn't shut off!

 

Now I'm not so sure inline resistors will do the trick.

Also still doesn't explain why Jeff's work fine!

Working on a fix. Suggestions MORE than welcomed.

Thanks in advance my '02 brothers.

 

R

 

post-43015-0-77872300-1452210199_thumb.j

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I don't seem to have that wiring diagram - can you post a copy of it? I'd love to have a look at it.

 

Not exactly your problem, however I've had other problems before with grounds (non stock wiring) where the windshield wipers were always one because of a current leak through a microrelay. A diode to block current going to ground fixed the problem.

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Don't have time to think this through in detail at the moment but electrically LEDs are a lot different to incandescent light bulbs. A bulbs has a changing resistance between cold and hot plus a small current flowing through a bulb may not result in visible light. Try swapping your relays out for new ones as a start and check the grounds in the lamp circuit.

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SOLVED!

 

Emboldened by sirius815's email to me, I connected a 25W/25 ohm resistor from the left hi-beam lamp wire (56a) to the left hi-beam ground (31) to allow for a pseudo ground for low-beam relay terminal 85.

This setup mimics what happens naturally with a halogen buld and was missing in the LED setup.

I'll be darned, works like a charm.

Thanks for the help and hope that this thread may help others in the future.

R

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Hmmm just noticed that I have a similar but different issue with my car. I have LED bulbs in my sidelights (city lights, running lights, parking lights etc) for longevity because changing the bulbs needs me to pull the whole 7" unit since I can' t get to the bulb by the back of the lamp.

Just noticed that even with the lights off that they flicker dimly when the engine is at idle. I will install similar 'pull down' resistors across each bulb to bleed off this voltage and see how I go.

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Thanks for that blog post Jdeitch! Was really informative when making the upgrade to LED headlights. I opted to avoid the lenses with the added 'city light' bulb as you mentioned they won't fit in the NA lens buckets. I picked up what I think is the same bulbs they are selling at www.vintagecarleds.com, for ~$50 on Amazon.

 

I also ran some tests with a friend to compare different bulbs and lenses: 

  • sealed beam halogen H4s vs. LED
  • Autopal Euro lenses with 'city lights' vs. Autopal DOT approved NA lenses.

 

We made a few insights:

  1. The LED bulbs were much brighter (no surprise), while drawing less than a 1/3 of the amperage of the old sealed beam halogens (no more roasting my dash light switches!)
  2. The Euro lenses had good cutoff (contrary to what I've heard) while also providing more coverage to the right of the driving lane
  3. The added 'city light' bulbs in the lens housing left a big shadow in the beam pattern as they were in the way of the reflector (seems like a silly design??)

 

 

Old H4 Sealed Beam Halogen

image.thumb.png.e32b589b813c5967b0308d1c8a31e141.png

 

New LED bulb in DOT approved Autopal H4 Lens

image.thumb.png.a4104ec3d6e1242f22fe219a78fb32a8.png

 

LED bulb in an H4 Euro Lens with "city light"

image.thumb.png.81f5c2e6f5ec7c740f531887f43b07ed.png

 

Side by side beam pattern of NA (left) and Euro lens with city light (on right), notice the extra vertical coverage on the right of the euro lens as well as the dark spot from the shadow of the city light bulb!

image.thumb.png.4e506d4ceec1f44a4b89e6f2abe731d4.png

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