Replace LED in third high mount center brake light

Discussion in 'General Electronics Chat' started by regexaurus, Mar 19, 2016.

  1. regexaurus

    Thread Starter New Member

    Mar 19, 2016
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    Our Ford Freestar recently underwent its annual state-mandated inspection. The (overzealous?) mechanic failed the third brake light (it has a series of 9 red LEDs). I have yet to speak with the mechanic and the only "problem" I see is that one of the LEDs doesn't light up when braking and one next to it is dim. Overall, the light is highly visible when braking. I disconnected both the unlit and dim LEDs from the assembly. Interestingly, if I use the LED that appeared dim to connect the posts on a 9v battery, it lights up and appears very bright. The "dead" LED doesn't light up at all.
    Rather than $150 to have the mechanic replace the light assembly, I'm leaning towards picking up a through-hole LED and connecting/soldering it in place. I have rudimentary electronics and soldering experience/ability. Any suggestions or things to look out for? Do I need to worry about voltage requirements for a replacement LED? If you can point me to a good choice for replacement LED, perhaps (nearly) identical to the LEDs in my assembly, it would be appreciated. The stock LED has a clear housing but shines red, even without the red lens for the assembly.

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  2. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    The leds will have series resistors on the pcb, you can lower the resistance on the dim ones to brighten it, they're probably all in parallel with their own resistor or maybe wired 2 or 3 in series. Search for high intensity red leds.
     
    Last edited: Mar 20, 2016
  3. wayneh

    Expert

    Sep 9, 2010
    12,103
    3,038
    I'd search for a replacement as close as possible, both physically and electrically. Since your 9V test did not destroy the LED (right?), the LED must includes a current-limiting resistor and certainly you want to use an LED meant for automotive, 12V operation. A generic LED will not be, and will pop like fuse if supplied 12V.

    If you could find a similar taillight in the junkyard, you'd have all the LEDs you'll ever need.

    One place you might find advice about part numbers and such is a forum dedicated to your vehicle. I use those for my vehicles and they can save an incredible amount of time. Just about any problem you encounter will have been solved by someone before you.
     
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  4. KeepItSimpleStupid

    Well-Known Member

    Mar 4, 2014
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    hp1729 and KJ6EAD like this.
  5. dl324

    Distinguished Member

    Mar 30, 2015
    3,242
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    If you can't locate the exact replacement LED, I suggest you buy a replacement module and install it yourself. If you substitute components you could open yourself up to a liability lawsuit if the vehicle is in an accident and fault is found with your modification.

    You don't give your location, but in the US all automotive parts must be DOT approved.
     
  6. KeepItSimpleStupid

    Well-Known Member

    Mar 4, 2014
    1,144
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    if your in the US try here: https://www.hollanderparts.com/

    They are basically a broker. Electrical parts are mostly non-returnable, but all you need is a couple of LED's.
     
  7. hp1729

    Well-Known Member

    Nov 23, 2015
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  8. Tonyr1084

    Active Member

    Sep 24, 2015
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    Here's a tip: Soldering is a bad idea. Why? Because the mechanical connection versus the weight will eventually lead to cracking (and creating an open circuit condition). Solder does not like heat expansion and cold contraction. Being that high up on the vehicle and in the sun, the solder joint will likely fail rather quickly. Given with the added shock and vibration, "Quick" may be an understatement.

    What about the solder joints in the ECU (PCM or whatever they're calling the computer)? Surface mount is less susceptible to vibration but still doesn't like the expansion and contraction. Different solder chemistry will have different heat coefficients (rate and amount of movement with temperature variation). Plus, the computer is housed in a well cooled box that dissipates heat. While heat continues to be a problem for computers, they've pretty much negated joint failure (solder joint). Your Cyclops brake light has very little if any solder on it. In some cases they use Ultra-Sonic Welding, in other cases they use clinching (smashing a piece of metal while in a confined hole (such as can be seen by post #4, figure 14)).

    Someone also mentioned DOT regulations. There's a reason why certain items are not acceptable under DOT. (Department of Transportation) Reliability and safety. If your Cyclops isn't working properly then it's a reject (during safety testing). And by "Properly" it means ALL LIGHT EMITTING ELEMENTS MUST FUNCTION.

    If you must - try a junk yard. OR go to RockAuto(dot)Com and input your year, make and model then search for a replacement for your vehicle. Order it and install it yourself. I'm certain it's an easy fix for you. If you can tackle testing and soldering LED's then you can certainly master the intricacies of a screw. In fact, it sounds like you've already bench tested it. So it's obvious you know how to remove it. Simply replace it with a working Cyclops. And keep the old one for messing with on your work bench. OR send it to me. I'd like to fool around with it.
     
    Last edited: Mar 23, 2016
  9. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,386
    1,605
    Just move the bad LEDs to the end so all seven in the middle light.

    Then return for inspection and see if the tech can count.
     
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  10. InspectorGadget

    Active Member

    Nov 5, 2010
    211
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    Ernie's got a great idea! Just leave out the bad LEDs, center the good ones, and go to a different inspection office. You'll very likely pass.
     
  11. Tonyr1084

    Active Member

    Sep 24, 2015
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    If you return to the place that failed you they'll reinspect the car for no charge within a certain number of days. If you go to a different place you have to pay for the inspection again. And what happens if you run into an inspector who knows his vehicles? What if he KNOWS you have two LED's out?

    Even a dimly lit LED is still a "LIT" LED. Dim passes. Out fails. And a 10 inch bar with only 6 inches of lit LED's is likely going to fail again. Save yourself a lot of headache and just buy the new Cyclops brake light. Can't be that expensive.
     
  12. erjs2000

    New Member

    May 19, 2012
    2
    0
    In looking at the picture of the back side of your assembly, I see what looks like a cold solder joint where the metal heat sink/circuit board has a tab coming into the board. Just to the right of the C1. You could try re-soldering that as well as the one on the other side. Since you already removed the LED's it might be tricky to put it back together if that turns out to be the problem
     
  13. Tonyr1084

    Active Member

    Sep 24, 2015
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    In comment on the cold solder diagnosis: First, I have over 30 years experience in PCB solder experience. IPC certified IPC610 (rev A at first, rev C for many years, pre-released rev D, current rev
    E) (Cert expires July 2017).

    That being said (and no intent to brag), the joint you call as looking cold - there's far too little light and magnification to determine it's cold. The top of the joint appears to be disturbed but there is good evidence of wetting at the pad.

    The LED that doesn't light up - regardless of 9V or not - indicates this is not a solder issue. The DIM LED lighting up bright - again, this is no indication of solder issues. In all likelihood the LED that is dead may have harmed the other by drawing too much current through it but not drawing so much as to complete destroy the diode. I have seen for myself where an over-current'd LED can diminish its output under normal conditions. I'm thinking the first LED to go was the one that went out and as a result the second LED (the dim one) was hurt.

    Regexaurus: It may be fun to continue trying to solve the issue but honestly I see this as an exercise in futility. Do as you wish but I still think the best thing to do is either order a new one OR go to a junk yard and buy a junk unit (or two). They CAN'T be that expensive at a junk yard, especially at a "Pick N Pull" yard where you pull the part off the vehicle yourself.

    Good luck.
     
  14. regexaurus

    Thread Starter New Member

    Mar 19, 2016
    3
    0
    Thanks all for the helpful responses! It was good to find out what I'm looking at.
    A special thanks to Tonyr1084! You're right -- and even while I look for individual SnapLEDs, I've been calling/checking with local salvage yards, on eBay, etc., hoping to find a relatively inexpensive CHMSL (center high-mount stop lamp a.k.a. third brake light) assembly. Though I'm sure demand would be fairly low (unless that was a common/compatible part across various Ford models), it's a shame the metal LED bar/assembly (as pictured in my earlier posts) isn't available for say $10-20. It was quite simple to disassemble the light to that point and I would gladly spend that to replace the light and get the van to pass inspection.
    I struck out at 2 local salvage yards and I'm waiting to hear back from a third. Part of the problem is my working hours and typical salvage yard operating hours don't mesh well.
    Dorman makes a compatible CHMSL in the $60 range I may end up buying.
    I found that--at least in my situation--replacement SnapLEDs are difficult to source. Future Lighting Solutions has what appears to be the correct part on their website, but no stock and even if they did, a minimum order of quantity 60. I submitted 2 inquiries on Alibaba for sellers that have low minimum order quantities.
    From further research, I've found that others have had limited success soldering SnapLEDs as they apparently tend to be quite sensitive to the levels of heat required for soldering. One person mentioned they use an alligator clip near the solder joint to draw away heat, and they were able to satisfactorily solder SnapLEDs this way. Another said this didn't help in their attempts. I may still try to replace the failed LED out of curiosity--even if I locate/purchase a salvage or other CHMSL assembly. If I do, I think I will try drilling very small diameter holes through the metal mounting "plate" and legs of the SnapLED, then use fine screws/nuts or possibly rivets to fasten. That was the best alternative I could think of next to the original "clinch" design or soldering.

    One potential problem I'll have with ordering a replacement is that apparently the Freestar CHMSL came in incandescent or LED (like ours) editions. They're probably compatible--electrically and physical wire connection, but won't know without trying.

    Tonyr1084, you use the term "Cyclops" a few times. What do you mean by that?

    Thank you!
     
  15. Tonyr1084

    Active Member

    Sep 24, 2015
    535
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    Cyclops was a Greek mythological beast with only one eye right in the center of its head. One eye - one brake light at eye level.

    Here's a link:

    Cyclops Greek Mythology
     
  16. regexaurus

    Thread Starter New Member

    Mar 19, 2016
    3
    0
    All attempts to source individual replacement LEDs (the SnapLED kind) met dead ends.
    I finally made it to a salvage yard. $15 and a bit of time later, I have a fully functional CHMSL (Cyclops). :)

    Thanks!
     
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