Our cars are getting old enough that the bulbs in either our door switches or heater controls are burning out;
I would like to know if anyone has replaced the bulbs in any of these - to date all I have been able to do is source used parts with good bulbs, or less burnt out bulbs.

I thought there was (many years ago) a thread that someone created on how to replace the factory incandescent bulbs with LED's on the gauge cluster, as well as the door switches, and heater controls - but I searched, and couldn't find anything.
I was looking for this, because I figured at the very least it would tell me the proper R&R procedure.

I do not want to replace the factory incandescent bulbs with LED (because that will screw up the dimming effect), but I'd like to find any information on how to source replacement bulbs, and replace them.

I would also like to know if anyone has a testing procedure for bulbs pirated (wink-wink) from cars in wreckers...
I think I have five or so good replacement bulbs that I took off some heater controls;
But I cannot at this time figure out how to verify they are good (without burning them out), and how to R&R them with bad ones from a spare heater control.

These bulbs are tiny!!

 

Can someone even tell me to proper size for the bulbs?

I came across this video (below), but I cannot understand spanish, so I can't quite follow;
But it looks like he is replacing the factory incandescent bulbs with a resistor and an LED.


I want to replace incandescent for incandescent.

T3 - T4 - T4.2 ???

Help.

 

I fixed mine just before selling the car. For the hvac I had a heck of a time finding the right size bulbs in 12 vdc and not led in the right size. I ended up ordering 3mm 12vdc ones which were too small. I think they are 5mm from factory. So I ended up just splicing them together in pairs twisting the leads and soldering them in that way. I ditched the plastic spacer as it was a huge pain to put back in after unsoldering it. The pair together was only slightly brighter than factory and obv retained the dimmabity. I figured if one of them burns out there will still be some light instead of zero since it’s kind a Pain to fix. Likely not being covid you could find the correct size bulb. The only way I could get it during covid is if I ordered like 200pieces for 30$. Found a 20pck of yhe 3mm ones for like 3$ shipped on Amazon. Figure I’d just go that route. Only ones I ever had burn out and needed to change. All three of my spare hvac did this lol. I only fixed the one.

 

thanks.

From some searching on eBay the re-occuring names seem to be T3, T4, or T4.2 but I cannot even find any information on these bulb types from google searches;
I found these listings all with the plastic bases - which is why I have named them.

I was sure that there was a write up ages ago on someone here who changed to LEDs - which in my mind would suggest they knew the correct size.

I think I understand what your're saying, and that I need to break out a micrometer to measure the bulb size to fit the plastic socket, and look for a 12 volt-DC incandescent bulb (if that was what 12vdc meant)...

I will post up if I get this figured out.

 

I just used a spare car battery to test the five loose bulbs I have here;
I never tried this before because I was worried that a 12v-dc battery would pop these right away.
1/5 works.
I also measured the width of these (OE) bulbs;
They were all 4.54 to 4.66mm wide.

Should I order 5mm bulbs?
(this assumes that a "4mm" bulb would be just under 4mm wide?)

If you have a bunch of your 3mm bulbs remaining, are you able the measure the width of them?

EDIT:

I don't know why I didn't think about this;
I measured the inside of the (blue) bulb socket base pulled off of other (cobalt) heater control boards;
Exactly 5mm.

I just ordered some 5mm-12vdc incandescent bulbs.

Hopefully soldering these on won't be beyond my capabilities.

 

5mm 12 volt leds. Solder them. I have made dozens of led swapped ac controls and clusters. Ive done door locks also

 

I wouldn’t get hung up on the plastic based either. Cool if they work for you but the wire is stiff enough if you shorten it enough they won’t move and there’s nothing super close to short too. They were still sitting a 1/8 inch or so away from the board so I had no worries about it melting or something.
I used the write up off of here to do it. It does exist somewhere on Google.

 

they absolutely work. He did say he didn’t want to use leds though. Which I get. Little to no dim ability. I also wasn’t looking for them to be any brighter just functional again hah

 

Both good options though

 

They dim just fine. I have no issues with dimming.

 

if you have observed some dimming effect with the interior lighting control - that's great;
LEDs function differently than conventional bulbs, and often you need a piggy-back control to make dimming function - and still you can have issues.
So you may see dimming, but the next seven people who do an LED swap might not - this is what I want to avoid;
I want the lighting to all match, and function like it did when the car was new.

This is my latest experience with LEDs & dimming;


As you can see, it did NOT work as promised.


I understand that I could toss the plastic bases, but I think their main purpose was to put them at the correct height for the light diffuser - and I figured that measuring the opening size would be a confirmation of the required bulb size.

 

That’s a aftermarket gauge. Its different. The dozens of ac controls I’ve made will dim like factory. As long as the bulbs are 12 volt. I don’t use the bases. I just solder a 12 volt 5mm led there. I also make color changing ones.

 

He was not giving instructions. He was just saying how he changed them, and with what changed it with.

 

good to know. Leds don’t always play nice with dimming function without a frequency Controller. Nice that the 5mm work as is.
I recall people having issues with them still dimming they just didn’t get even close to as dim as the stock bulbs were able. To do. Not a big deal to everyone. How did you find the leds at there dimmest setting compared to stock at its dimmest?