How To: Defrost switch breakdown (for bulb replacement)

[OB]

After doing some research, I have yet to find someone who has disassembled the rear window defrost switch assembly to determine what kind of bulb it takes. I decided to tackle it and solve the apparent mystery. Here's how it comes apart and what I've found:

Step 1: Remove Defrost/12V ACC/cubby assembly (below HVAC panel).





Step 2: Use two flat head screwdrivers to unclip the switch assembly from the body of the cubby assembly.





Step 3: Again, use the screwdrivers to separate the two halves of the defrost switch assembly.




You will end up with the two halves of the switch case, and the printed circuit board that they house.





This picture shows the bulb; (blue cap is the cover that gives it it's color/tint). The cover can be removed with a good twist/pull motion, exposing the head of the bulb.




So it looks like the bulb is a wedge type, very similar to those used in the HVAC panel. The only difference is the overall length, which is much taller than a standard wedge bulb. I test fitted a stock wedge and it fit with a little massaging. Trimming the pads on the wedge should make for near perfect fitment. Time to hit up SBL for an LED replacement! Hope this helps those of you who have done the LED swap but haven't figured out the defrost portion. Might also help if you have any other issues with the defrost circuit

[Jenni]

you don't have to open the switch to remove the bulb!!!

[blueneo03]

i think he was just showing what it looked like a little.. and craftsman FTW!!

[RayWolf]

if you dont have to remove the switch to change the bulb what do you do then?
also what bulb size is it?
im planing on doing ultra white leds in my HVAC and Culster to give it that blue glow to it

[Jenni]

read!

you don't have to OPEN the switch.
remove the switch and you see an hole in the housing. There sits the bulb.

LED is easy: 3mm and a resistor.
I prefer blue LEDs in switches.
Other than the bulb has the LED to look directly to the front of the switch (bend 90°...).

[wiggyx]

Even easier, just switch the bulb. They make tall LED neo wedge bulbs. You don't need to do any soldering or any other bs.

Carsten, we know you prefer blue and don't prefer red already. I think you've stated it a hundred times now

[occasional demons]

The bulb is not a wedge, at least it wasn't in mine. It has two long leads, that wrap around the base to make contact. Unless the newer ones have a different base.

Edit:





The replacement bulb is not the brightest. I cannot find the bulb in the oem parts either, so if the newer base is different, then I may have to scour the JY for an upgrade. My base looks the same, externally tho.

[OB]

It can indeed be removed without disassembly. I just wanted to check out the circuit board and figure out how it all came apart. I had to use 4mm LEDs for my HVAC BTW. There seem to be several lighting differences from trim and year to year.

Bill - Correct me if I'm wrong, but that second picture shows a wedge bulb. Way different from the first pic. Guess they must have changed the design for the newer cars.

Oh also, does anyone know what LED replaces the #74 in the cupholder lamp?

[Danteneon]

Oh also, does anyone know what LED replaces the #74 in the cupholder lamp?

T5mm base to fit standard #74 or #37 sockets

They have multiple bulb widths depending on how much space you have to work with.

[occasional demons]

Bill - Correct me if I'm wrong, but that second picture shows a wedge bulb. Way different from the first pic. Guess they must have changed the design for the newer cars.

The second pic is the bulb installed into the base. The base has two small holes the wires need to be threaded into. They then wrap around the bottom twist lock to make contact with the board. I couldn't get a close enough shot of the wires.

[OB]

Ahh. So you just replaced the actual bulb in the wedge base then?

[occasional demons]

In the part that screws onto the board, if that's what you mean. By the "base" I mean the gray stand that the light fits into. Mine has no contacts other than the wires coming from the bulb. I had to strip the insulation off of the RS unit to make it work. So does yours have the standard wedge socket inside the gray stand/extension w/e you want to call it?

[OB]

I assumed the gray base was what made it a 'wedge'... Based on the way it fits on the printed board with the twist. AFAIK all bulbs of that type have the bulb with the leads coming out of them, and they wrap around the base for contact. Some are soldered, like on the newer models. Some LED companies make just the drop in bulb complete with base, while others sell the inner actual bulb part with the leads. I've seen both.

[occasional demons]

Ha! So you didn't remove it. It is teh Suck! Even the RS one was a little big for it, but I made it work. An LED would prolly be better, as the wires for the bulb were stranded. A 3mm would prolly be best.

[Danteneon]

If that is the right sized base (10mm), but methinks it is too big

[occasional demons]

That may just be it. Judging from my pic above, a dime is 18mm, so the very bottom of the base looks about right, and the 19mm length looks very close to the dime's diameter.

Me thinks you haz a winner!

[Jenni]

the problem with that led is: the angle is wrong.
Sure it is the same as in the stock bulb.
but the stock bulb has a very wide lighting angle (almost all-round) on the contrary the led lights up punctual.
So with shown led you will very nice light up the housing but not the defroster sign.
So you have to bend the led at the top end 90° that it shines directly to the defroster symbol.


Unfortunately i cannot remove the defroster switch in my car (that screen comes really not off that easy) but here is my way:

- find out + and -
- remove the bulb
- cut the wedge socket in 2 pieces (remove the long grey "tube")
- stick the resistor through one hole into the wedge base (from the bulb side!
- bend the resistor wire like the bulb wire was before
- stick one of the LED pins through the other hole and bend it also
- LED lengt should be here the same as the bulb used to be!!!
- solder other side of resitor to other pin from the LED
- testfit (especially for polarisation)
- bend the LED 90° that it looks directly to the front of the switch
- test if you have any shadows left in the defroster symbol.
if: correct the led.

[wiggyx]

The best solution that I've found (without doing a lot of work) is to simply use the normal, shorter style SMD LED neo wedges in the defrost switch. It puts the bulb far enough back to give the light a chance to shine through to the button.

[occasional demons]

The LED the Dante has shown is an inverted style, so it throws the light out the sides also. It is plug and play.

I imagine it is also rated for 12v, as there is no way to install a resistor in the oem light adapter. You can see in the Autolumenation pic how the leads from the LED wrap around the base flange to make the contact.

Edit: Like Wiggy said the normal one will work, it really doesn't take a lot of light. Unless you like very brightly lit stuff, it would be just fine.

[OB]

Yeah if you look into the housing, there is a mirror in there to reflect the light to the button. It's the only way it will work based on the way the board is setup in relation to the switch.

[OB]

Ok, so it looks like the NEO4 LED from SBL is the correct replacement size for the defrost bulb. I ordered the NEO3 and it was way too small. The NEO4 base is dead-on the same as the stock bulb.

Also looks like I'm going to need a resistor for the Cupholder lamp LED I ordered; it pops 20A fuses like they're going out of style.

[RayWolf]

i just took apart my defrost switch and removed the blue cover. now ii will not light up, but everything else works. im stumped.
i tried messing with the contacts and switchign the bulb base back and forth. still noting.
i could use anyones insight to help fix this problem.
Thanks
Ray

[occasional demons]

Possibly the wire going into the bulb broke, when you pulled off the cover?

[RayWolf]

maybe its the wire in the tube im guessing.
going to the Junk Yard tomorrow, so i will pick up a new one and cut the cover off not pull it off this time.

[OB]

The bulb may be polarized, if that's the case flip it around and try it. That's how a lot of LEDs are, including the one I used to replace my defrost switch bulb

[RayWolf]

well its the stock bulb and have tried the flipping, and still not working.

did look into an led repacment at radio shack but its like 5 bucks for one led. way to much for me right now. but well see later on.