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replacing leds inside switches

3K views 10 replies 4 participants last post by  Magnasport 
#1 ·
I know I read about this somewhere here but after an intensive search I can't find the thread. No idea what it was called. :)


The back-light lights inside my heated seat switches have gone out but the indicators to let you know they are on high\low mode still work. Started on the passenger side and I am confident it is 100% the switches. Before the drivers side went out I swapped them side to side and the working one worked no matter where it was connected. Now they are both out. Borrowed one from a buddy and it still lights up but both of mine are out.


Done a bit of searching online and the best I have found will cost me around $50 Each shipped and I'm just not doing that for the benefit of a back-light. I will try and fix them myself. So, before I dig into them I need to make sure I have everything I need. Anyone know where I can find the thread here about how to replace the smd leds inside the switches? Anyone know what size led they use (ie 3010, 3014. 3528 etc)? I have to assume wither 3010 or 3014 just due to the small area involved but I can get pretty much any size...only need to know ahead of time. :)


Failing that does anyone know of a place I can get GOOD, working replacement heated seat switches that is NOT a stupid price? Lol And fyi the wreckers is not an option. I've already called around and none anywhere near me have any and fully admit they just toss them once they start stripping a car down.

Thanks everyone.
 
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#2 ·
Update: Never mind. :) Found what I needed, just not here. Found a great thread here: How To:Change Interior Backlight Color (NAV, HVAC, Switches, etc.) PICTURE HEAVY!!! - Dodge Charger Forums that explains everything I need. And from what I can tell I won't even have to buy anything. With literally THOUSANDS of leds and resistors on hand in all manner of sizes and ratings I should be able to swap out the back-light (turns out it is actually a bulb) fairly easily. Now, the question is "what colour?". :)
 
#3 ·
Thanks for this thread. Mine are starting to go out as well.
Driver's Seat Heater Switch, and one of the A/C Control Unit Bulbs.
Now that I'm moving into a new home, I'll have a Double Car Garage, and I'll be able to do some work.
 
#4 ·
I'm planning on doing it this weekend. I suspect the bulbs are the standard "dirty white" incandescent with a green filter in the switch itself. I think at this point I am just going to try and get them to look stock so I will use a 3mm warm white led. But I think I will replace the smd leds with pink ones to match the interior lighting I've done. But need to pop open the switch to find out what size I need before I order. From the pics they LOOK to be 1206 but they may be a whole 'nother size. :)


Either way I will try and post some pics as I go...but I am REALLY bad at remembering to stop int he middle to take pics...:)
 
#5 ·
Interesting. I want to do this, because the passenger seat switch has never lit in the time I owned my Karen-mobile.

When I bought the Karen-mobile, the heated seats did not work at all. Turned out that the previous owner had spilled some sort of soda on the heated seat control unit under the passenger seat. Replaced the control unit, and now the seats heat perfectly.
 
#6 ·
Popped open one of the switches and the main bulb is definitely burned out. Did a bit of checking with a continuity meter and figured out which pins power the main bulb and the hi\low indicators.

The indicators are definitely 1206 smd amber leds and if you're good at soldering and have a steady hand they should be "fairly" easy to replace. I want to replace them to match the same pink interior lighting I've done...so now I have some on order. :) The smd resistors are 620 ohm so they should run the new leds somewhere in the 17-18 mah range...well within tolerance and not so bright as to be overly bright.

The main bulb has a blueish rubber type cover that just pops off and it can be replaced with a 3mm or 5mm warm white led (I happen to have 500 3mm on hand) and use the same blue cover to give the stock greenish colour (if you want to stay stock looking). A 560 ohm 1/8 watt resistor on the anode will safely drive it without worry about it burning out. I'd be shocked if I didn't have one of these in my kit. lol

So now that I have the basics in hand and am just waiting on the new smd leds (prob take around a month) I will actually try REALLY hard to take some pics as I do this and post something if anyone wants to try their hand at this. If you do I will recommend 2 things: get a "third hand" to hold the circuit board while you're working on it and get a set of good magnifying glasses 10/15 power is best. These suckers are small and you'll really strain your eyes otherwise.

In the pic I've noted the pins that power the main bulb (purple & blue) and the smd leds (D1 & D2) for anyone interested in digging into theirs. Keep in mind that while most sources will say our cars run on a 12v system I've measured the voltage at these points at 14.3v (engine running). With an led running at a typical 3.4v that means a 10.9v drop over the resistor not 8.6v (if on 12v). If you base your resistor value on a 12v source you will end up over-driving your resistor upwards around 25mah. Not a HUGE deal but enough that you should expect a shorter lifespan from it. Drop the current to under 20mah with a 560-620 ohm resistor and you won't have to do this job again. :)
 

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#7 ·
Update: I finally got all the pieces I need to begin this project and have the first of the heated seat switches done. Popped it back in this morning and I must say I LOOOOOVE the way it looks. So now on to the rest of them.


I will grab a few pics tonight and hopefully be able to update again tomorrow. Other than my old eyes needing help from a set of magnifying glasses it is really an easy task. The waiting for all the LEDs and resistors has been the toughest part for me. :)
 
#8 ·
You'll have to post a complete list (once you're completed) of part numbers (and sources)... Along with all of your photos.
I'm keeping an eye on this one.
 
#9 ·
Updates coming tonight ( I promise). Stay tuned. :)
 
#10 ·
Ok,

Here's what I have so far:

Pics are only of the heated seat switches with the heater indicator leds and running light lamps replaced. Haven't gotten to the other switches yet but now that I have at least this much done and figured out my "system" I figured it was time to share. Sorry for the delay James. :)

An important word: this involves some delicate soldering. Not physically difficult but ABSOLUTELY NOT for the novice. If you don't have much soldering experience (electronic experience preferred) PRACTICE A LOT before you even try this!!!! I'm NOT kidding!!!!

Even if you've got a lot of experience playing around with this stuff I highly advise reading it a few times to make sure you feel up to it. Test ALL of the existing leds first (see bottom for pinouts) to help familiarize yourself with the circuit on the board.

Work in a clean, well lit and well ventilated area and take your time.

Tools used (but not all required...just made things easier):

20w soldering iron. I wouldn't go higher than 30w or else you can risk de-laminating the copper from the board.
Non- Acid (VERY IMPORTANT!!!) paste flux (square container). I use this to help tin the iron tip.

Soldering tip cleaner. Lots of options for this. Mine is just copper wool that does a great job of cleaning oxide off the tip as well as old solder. I've found that steel wool doesn't pull the old solder off as well. Just my preference.

Mini side cutters and bent-tip needle nose pliers.

3rd hand with magnifying glass (built in led light as well).

Nice BRIGHT LED flashlight.

Small gauge flux-core solder (I use 1mm typically).

Low temp (168°F) paste solder. Basically powdered solder mixed with flux. Same stuff they use in industry by screen printing onto the boards before they place the smt components on. Not mandatory but makes things simpler.

Magnifying glasses. Left side has 10x lens and right has 15x. Again, not mandatory but they REALLY come in handy when checking joints, looking for cracks, general inspection...I will revisit below.

Parts used:

5mm flat top leds. I find the flat top provides a better light distribution. I tried with a round top and found them to be a little brighter in the middle and dimmer at the edge. Flat top was over-all a more even lighting. 3mm will work as well but again, I found they had a "hot spot" in the middle and not as diffused. Will revisit below.

1206 SMD/SMT leds

1/4w 620 ohm resistors. Smaller size is best here but don't go lower than 1/4w.

Sources:

Leds, low temp paste solder, resistors: all from ebay. I typically buy all my electronic components from ebay. I buy in large(er?) quanities. Per unit cost is way less this way.

100pcs 5mm Pink flat-top leds; $12 shipped. 50pcs was $9. Figured it is always a good idea to have extras. I just add the rest to my LED bin. Seriously I have thousands upon thousands of leds in there. :)

20pcs pink 1206 SMD leds; $4 shipped (and all from same reel so would be from the same bin meaning they would all have the same colour, brightness and power consumption). Probably more than I will need but I would rather have a few spares in case I burn one out, overheat it when soldering, drop it in the carpet (ask me how I know about that one)...

200pcs 620 ohm resistors: $2 shipped. I use these all the time and have all manner of different values. never know when I will use them. At this price they are essentially disposable so I don't worry if I ruin some while I figure out my design.

Low temp paste solder: $15 shipped. The 100gm tube will literally last me for years if not over a decade as long as I keep it refridgerated.


The rest I acquired from a few different places depending on deals I find at different times. I typically buy from tmart.com, newfrog.com or tomtop.com. I don't recommend one over the other as they all typically have the same stuff from the same manufacturers. It usually comes down to price and shipping. But between ebay and these 3 this would cover 99% of the stuff I buy for whatever project I am working on.


Moving on to the actual work:

WORD OF WARNING: The pins on the board are surface mounted and the solder joints are somewhat weak and brittle. Avoid ANY real force on the pins as they are VERY easy to pop off the board (ask me how I know). I won't go into how to fix them here but if you need to know I'm happy to answer.

Removing the old lamp was easier than I thought it would be. Seems to just be pressed in place but you HAVE to remove the white plastic base too. That gave me a little hassle. Needle nose pliers to the rescue. The plastic is quite brittle so it broke apart very easily.

Removing the indicator leds is fairly simple but delicate. I held the board with the 3rd hand and while heating one side of the solder joint I pushed in from the other side with a small jewelers screwdriver just enough to lift the led off the board slightly. Then move to the other side of the led and repeat. Should pop right off. Be SURE to let the solder fully melt before you push or you might break off the solder tabs and have to clean them off the board. Again, not hard but when you're working with very small parts and have big hands (and old eyes) it is better to be careful, slow and deliberate rather than rushing through it. :)

Make a note of the green marks on the backs of the leds. This notes the polarity. Industry standard markings here so just make sure the new ones go in the same way as the old. Pretty simple here.

(Not something you'll work on but I think is noteworthy) The blue chips on the switch side of the board are the resistors for the indicator leds. They should be 610 ohm (that's what mine are marked as and measured as) and won't need to be replaced unless you find the indicators to be too bright. The leds I used run at 3.4v and I measured the supply voltage at 14.4v (with engine running). This means the leds are being driven at a tad over 18ma (ohms law is your friend). The ones I used are rated at 30ma so WELL within tolerance and VERY bright. Whatever leds you chose be VERY aware of their typical running voltage. Red, orange and yellow (in that order) typically run between 1.5-2.5v so this means that they will actually have more current to them with the stock resistors in place. But again, unless you find the new leds are too bright you shouldn't have to worry about this. If you need help with this I am happy to answer any questions.

It is always better to over estimate the supply voltage than under estimate. As I measured mine at 14.4v with the engine running I used that as my "standard" and based all my calculations around it. The 5mm leds also run at 3.4v with a 30ma max current but I almost always under-drive them. Using 620 ohm resistors means they are running at JUST under 17ma and are the perfect brightness for my taste. if you want brighter you could go as low as 365 ohm but they are MUCH brighter and I'd be worried about burning out the leds and having to go through it all over again. 5% tolerance resistors are fine but I typically try to go with 1% just to keep things as similar as I can. Cost difference is negligible.

Installing the 5mm leds isn't easy but not hard. I would say a 3 out of 10...but being small parts and having big hands I just take my time. If you've ever built model cars you already have the skills you need here. :)

I slid the leads into the lamp hole from the switch side (front of the board) until it stood about 1/4" off the board (from the bottom of the led). The leads were around 3/8" in total length measured fromt eh bottom of the led. The negative lead (cathode) was then bent 90° to the side and the positive (anode) bent 90° down (if looking at the led from the underside neg on right and pos on left). Think of a clock...cathode at 3, anode at 6. The ends were then clipped about 1/8" from the bend. Here's where it gets a little tricky. The resistor lead was cut to about 3/16" and wrapped around the anode and soldered. Be SURE to leave just enough "slack" in the resistor lead to allow you to bent it to the left (same direction as the cathode...3 on the clock). This part is not mandatory but I slid heat shrink tubing over the resistor and down the anode all the way to the led base to prevent any chance of a short circuit. Then I bent the other resistor lead all the way back to the right (right against the heat shrink I just put on) and put another small piece of heat shrink over that to again prevent any chance of it shorting out. Any kind of insulation will work here (electrical tape, non-acid silicone, shoe goo...etc) but I have a LOT of heat shrink in many different sizes so I typically go that route first. I buy it by the 100ft roll btw. :)

Now...I am REALLY hoping that the pics here help make sense of what I just wrote. If you are holding the led "lens" between your thumb and fingertips away from you and the leads pointing towards you the cathode should be bent off to the right, the anode is bent towards the floor, the resistor bent towards the right and the other resistor lead then bent 180° off to the left. (I really hope I didn't make things more confusing). Basically neg lead at 3 on the clock and pos at 9.

Now that you have the resistor attached to the led leads clip the ends off so they are about 1/8" long. Here's where you have to get creative. The hole is smaller than the led so you can't pass the led through the back side of the board. But the leads and resistor are too big to fit through the front side of the board. What to do? I found 4 options available:

1. Do all of the above with the led leads already passed through the hole and working from the back side of the board. This option didn't work for me as I have big hands, only 3 hands, and old eyes.

2. File/sand the bottom lip of the led enough to allow you to pass it through the back of the board. Again, big hands and old eyes made this too tough.

3. CAREFULLY (can't stress that enough) bend the leads however you need to manage to get them both into the hole at the same time followed by strategic wiggling until the leads and resistor pop out the other side. This was my personal favourite and I found it took about 10 seconds to figure out. I would advise trying this option first. :)

4. Use 3mm leds. I didn't like the light pattern. Too bright in the center (hot spot). 3mm flat top might have a better diffusion but I didn't have any and wasn't about to buy some just to test. I still feel they will be a tad to center hot.

Now that you have the leads passed through the board you need to "adjust" them again to make sure they are straight up & down and the ends are pointing 180° apart and level with the board (3 and 9 on the clock).

The board contacts for the old lamp have been tinned already (pre-soldered) but I found it best to give them a slight scraping first (makes them shiny). If not the new solder didn't seem to stick well. You can use standard 60/40 solder here and a narrow gauge is best as the area you'll be touching is small.

Personally this is where I found the low temp solder paste to come in very handy. A tiny dab on the board contacts helps hold the led leads in place and once you touch the soldering iron to it it melts quite easily and flows well. Do what works well for you. If you decide to use the paste solder try it out on some parts you don't mind ruining. It isn't tough to use but there is a bit of a learning curve and it is best to figure it out before you risk killing one of your switches.

With the pin side of the board facing you and the indicator leds at the top, the cathode is on the right and the anode on the left.

Test with a 12v battery. Touch the corresponding pins for each led and if they light up you are done. Just need to put the switch back together.

With the board in the same orientation as above the pins are as follows (left to right, top to bottom...same as you would read a book);

1. Signal 2. 5mm pos 3. LED neg 4. Signal
5. LED neg 6. signal 7. 5mm neg 8. LED common pos

Ignore the signal pins. Be careful that you do not put any sideways pressure on the pins or you risk one or more popping off the board (ask me how I know).


Now...a final word of warning. If you use the paste solder it can "spatter". Not unlike MIG welding. but nowhere near are messy. Just be prepared to wipe off any residue or "micro beads" of solder.

This is also where the magnifying glasses and LED flashlight come in handy. After it is all done and tested I advise giving EVERY solder joint you touched a good look-see. Make sure all the joints are smooth and shiny. No cracks. No bridging.

I hope this helps. This is WAY harder to write and to read than it is to actually do so don't be discouraged. Once you do your first one you can consider yourself an expert and you should feel very confident in trying this on other parts.

Let me know if you have any questions or if I confused you at all. :)
 

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#11 ·
The lights in my 06 Magnum A/C controls went out several years ago and I replaced them with 12v bulbs I found at radio shack,
they seemed fairly dim but they worked ok. Recently and for the hell of it I decided to upgrade all my interior lighting
including dash lights to led. Making some voltage checks here and there to find the positive sides I found out that the A/C controls use only 6 volts for the lights
which explains why my bulbs were dim, replaced them with prewired 6v leds I found on e-bay (bag of 5 for $3.00) I
lightly sanded the Leds to defuse the light better and they came out perfect.
My point for this reply is to let others know that not all dash lighting is 12v, check before you buy and if you want 360 degree
light dispersion from an led, get the frosted ones or you can lightly sand them till they look frosted. Also you'll find good quality leds in all types, sizes and voltage ratings on e-bay dirt cheap.
 
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