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Thread: Headlight rely system with LED bulbs??

  1. #1
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    Headlight rely system with LED bulbs??

    Wondering if the rely setup is still needed?
    Thanks !
    Creighton

  2. #2
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    Get an amp clamp meter and check draw...

    I think the relay mod is a bandaid for an abused electrical system

  3. #3
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    Thanks!! Agree to a point. Think also a preventive measure. Worth the effort not sure.
    Creighton

  4. #4
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    Quote Originally Posted by KMT View Post
    Get an amp clamp meter and check draw...

    I think the relay mod is a bandaid for an abused electrical system
    Not really, KMT.

    Consider that a stock 9004 is a 55W/60W bulb. Two of them on high is 120W. At 12V nominal that's 10A.

    Do you REALLY want to drag that through the car to the the switch, to the MFS, and back? Switching the relay means that you only see something like .2 amp instead.

    (For fog lights, you're looking at 110W + 110W, or 220W, closer to 20A through the switch. Yee-OUCH!)

    It's a fix for a cost-engineered light circuit.

    Also, here's one for you to consider.

    On my old 2000 Malibu, relays brought the voltage up from 12V to the full 13.8V at the passenger side light; that's 1.8V of drop, at 5 A, or 9 watts of heat dissipated somewhere in the circuit. And if you don't think 9W of heat can be hot, grab an old 7W incandescent bulb sometime when it's been on a while ...

    RwP

  5. #5
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    Quote Originally Posted by RalphP View Post

    It's a fix for a cost-engineered light circuit.
    Raise the bridge or lower the water - rather than hacking the wiring to support a mis-applied load, I'd rather keep an otherwise serviceable OEM system intact, and lower the load w/LED fogs (note that LEDs for our application(s) are getting brighter every year now). Less cost, less work, cleaner/fewer new points of failure down the road.

    I think the stock fog lights are more cosmetic than they are functional. Brighter filament bulbs don't fix the problem and risk frying the plastic housings. Purpose-built fogs (where its more about aiming than simple output) don't readily fit the holes and look out of place on the sleek front regardless of where they're mounted. I thought about using them as DRLs, but went with thin LED strips instead, which are on their own switched circuit and don't carry a load requiring a relay.

    So, if the intent, is to upgrade the fogs themselves and simply throw more light, the solution is to always place them on their own balanced circuit, as God intended... or, go a different direction entirely.

    I've installed countless fog lights on big and small, service rigs to my own rides, but today I find a forward-facing camera with night vision to be a much more advantageous approach. Just like LED bulbs, the tech has changed and given us more options over what we used to do to make our drive safer.

    Ken
    Last edited by KMT; 12-05-2016 at 12:06 PM.

  6. #6
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    Umm ... Ken? Didn't hack the wiring; all of mine is added.

    (I also had to convert from a 9004 to a 9005/9006 pair since I also modded my 1991 Cougar with the Grand Marquis headlights that the sucker SHOULD have had from the get go for looks, IMO ... oh, and for light.)

    So any time I want to, I can convert back to the factory 1991 Cougar headlights.

    Why, I dunno, but I could.

    (Did the same on my Dakota; a 4666/9003 adapter gave up its life, a pair of 4666 sockets, and then a 4666/9003 adapter at the output for my 4x6 / 9003 conversion set to use the Hella 55W/100W bulbs for night driving in the Dakota. Again, no factory wiring was hacked or chopped up; the relay harness in total is added.)

    RwP

  7. #7
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    To put mine back to stock, all I have to do is swap the fog light bulbs

    I'm sure you did a first class job in any case - I forgot we talked about that kit just last year. I don't think I've ever owned a car I didn't make some changes to, so I'm with you.

    Do we know if anyone still sells the relay/harness kit for our cars?

    Ken
    Last edited by KMT; 12-06-2016 at 12:15 AM.

  8. #8
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    Great information here folks, many thanks!! The fogs as per factory would have limited use here. Like the forward IR camera idea. Regardless...

    Want a separate circuit/switch. Looks like next to the "auto-dim" is a good spot for a period correct rocker switch. Idea's?
    If there is already one I'm sorry. Snowing and darn cold so dashes out to see what is what are reduced :-).
    Thanks
    Creighton
    Last edited by Creighton; 12-06-2016 at 01:00 AM.

  9. #9
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    I put a small (round/lit) rocker in the same area as/next to the headlight switch for my DRL strips. Was a tight fit, tho, as the vertical metal plate that holds the headlight switch is very close off the back of the cluster bezel. Just be sure to leave enough wire and a disconnect for the next time you want to remove the bezel.

    I have two other rockers located on each side of the two-piece plastic housing that sits between the steering wheel and the dash. Lots of room there, easy to reach while driving, etc. You might find that location easier.

  10. #10
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    lED haeadlamp bulbs

    There are a ton of the newer LED headlamp bulbs out there now for our cars. Some have fans and some have heat sinks. Anyone tried them?

  11. #11
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    Quote Originally Posted by 1qwik99 View Post
    There are a ton of the newer LED headlamp bulbs out there now for our cars. Some have fans and some have heat sinks. Anyone tried them?
    The biggest problem is, virtually none of them have the light source in the right spot for a halogen reflector.

    Even if brighter, they won't be as efficient.

    (I suggest a good relay system and 9011/9012 HIR bulbs myself; oh, wait, that's what I DID on my 1991 Cougar )

    RwP

  12. #12
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    I'm a big LED fan, but Ralph is correct - until you replace the lens/housing with something that leverages it across the board, you're not going to genuinely profit from modern headlight technologies.

    Ken

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