Gauge cluster bulbs - LED replacements?

Simba

New member
Next up, the HVAC buttons. I cannot stress enough how much of an amazing PITA it is to do these, nor how easy it is to break them, so you should be reallyreallyreally sure you want to do it. The backlighting bulbs are easy enough, the button LEDs are not.

First, you need to pull all the backlight bulbs out of the HVAC cluster, remove the AC switch board, and finally remove the white backing plate. Once you do, you'll have this:

hvac-back.jpg


The 12 LEDs for the flow control button and HVAC buttons are now visible. Each small white "box" with the diode label above it is a LED. In order to change them, you need to remove this board, and in order to do that you must remove the buttons from the front of the unit, like so:

hvac-switches2.jpg


The buttons just snap into the white actuators under them. However, the plastic is very fragile and prone to snap. If you snap the little tabs off the buttons, they will need to either be replaced (good luck finding them), or epoxied on. If you epoxy them, you will never be able to take the controls apart again, so make sure you pick a color you'll be happy with if you want to change the LEDs.

The rear defrost button snaps out of the housing via two nearly impossible to get tabs, and pulls out backwards. More on this little SOB later.

Once you have the board free of the housing, it'll look like this:

hvac-switches.jpg


You must then remove all of the white button actuators without breaking them. This is also an amazing PITA, and requires some very gentle work with a screwdriver to pop them off of the blue tabs without snapping them. I managed not to break any, but the removal process took three hours. When they're off, you can pull the clear plastic light channels off the board, and be left with the buttons and the LEDs:

hvac-leds.jpg


In order to remove the LEDs, you need to desolder them from the back of the board, while pulling them gently out of the button holders. This is a complete PITA. Using a kelly clamp makes it a little less annoying. Once they're out, you can insert your new LEDs. Again, you must insert them with the correct polarity. Match the long positive annode of the led to the "arrow" side of the diode diagram on the back of the board.

There's one other LED you can replace, which I didn't photograph, and that's the "on" light for the AC button. It's fairly straightforward to desolder and replace it. I used blue for the hell of it, even though my AC system is presently removed. :twisted:
 

Simba

New member
Finally, you can do the last button, which is the most complete PITA ever imagined: The defroster button. Once you manage to remove it from the HVAC controls, you will find there are two bulbs:

defrost-orig.jpg


One is for the backlighting of the button, and the other is for the "on" light.

Once you rip the switch apart, which is in itself a PITA, you'll see both:

defrost-origlight.jpg


The small green one is the backlight. The large one is the "on" light. Here is another place you can use a 5mm 360 degree LED, for the "on" light. I used a red LED to match the HVAC LEDs, and then used a 45 degree white LED for the backlight. It worked reasonably well in this switch, but it could be better with a 3mm 360 degree.

defrost-newleds2.jpg


It's a good idea to give the contact points a good splort of dielectric grease before you reassemble the switch. Then comes the fun part:

defrost-newleds.jpg


This is the bottom of the defrost switch board, with the LEDs installed. The trick is, there is virtually no room under the defrost switch for the required resistors, due to the AC switch and how the defrost switch snaps into the cluster. The best solution would be to source some smaller resistors. I used normal sized resistors, and as a result, I had to trim the mounting sheath in the HVAC cluster slightly to clear the resistors once the switch is installed.

Also, if you get the polarity wrong, you'll get to rip the whole thing apart again and turn the LED sockets around.

All in all, I'm pleased with the results, and once I find some 3mm 360 degree white LEDs and get some tiny resistors, the backlighting should be up to par with everything else.
 

___Scott___

Active member
Simba":3qvc4t7m said:
The annode of the LED (longer prong)
Unfortunately this is often, but not always, true. It varies depending on the manufacturer. What is always true is that when you look inside the LED you'll see that one side is big and the other is little. The big side is always the cathode (-). In this pic, the anode (+) is the upper leg and the cathode (-) is the lower leg:
component_ellipse.jpg


Also of note, is that the forward voltage drop across white or blue LEDs is higher than for the more common green/red/amber LEDs. Blue or white LEDs drop around 3.5V, whereas green/red/amber LEDs typically drop closer to 2.1V. The current limiting resistor you choose to use is also dependent on the nominal forward current allowed for the particular LED, which can vary typically between ~5mA to ~30mA.
 

toayoztan

Moderator
Also, another note, when taking out the rear defrost button, be SURE you are careful sliding it out. That spring Simba shows in the pic you must not lose or you'll need to get another spring.

Oh, and i'm not sure if it was mentioned, but the key halo is another nice feature to change colors on, and is very easy. It uses a 74 wedge bulb or LED. You'll need to remove the black trim piece surrounding the key cylinder, then if you look under the key halo, you'll see one brass screw. Undo the screw, the halo will slide off the cylinder, and you'll see a 74 wedge socket to undo, very straightforward.

Bryan
 

Simba

New member
toayoztan":8dx40odr said:
Also, another note, when taking out the rear defrost button, be SURE you are careful sliding it out. That spring Simba shows in the pic you must not lose or you'll need to get another spring.

Yup. There's also a small ball bearing in the top of the switch which likes to pop out at light speed. I hate the rear defrost switch with a passion.
 

toayoztan

Moderator
I suppose I should probably add my tidbit to Simba's write up. Here are some pics of the 92-93 HVAC (since they are different from 90-91) to give those an idea of what to expect. However, the directions for disassembly, etc can still be followed from Simba's writeup above.

For the LED indicators for the HVAC buttons and window switch, i used LED's that can be bought in various colors from Radio Shack:
wreckedtrunk020cm4.jpg


Here's a view of the LED indicators installed. I chose the color Red. All of them are installed except for the last one (i was still working on it).
wreckedtrunk021zn9.jpg


These 4 arrows show the microbulb locations that illuminate the HVAC controls on a 92-93.
wreckedtrunk028xu9.jpg


For the rear defogger, the red arrows point to the spring and ball that you need to be careful not to lose when sliding the circuit board out of the rear defogger button:
wreckedtrunk032uj4.jpg


Bryan
 

toayoztan

Moderator
Simba":acvwov1m said:
toayoztan":acvwov1m said:
Also, another note, when taking out the rear defrost button, be SURE you are careful sliding it out. That spring Simba shows in the pic you must not lose or you'll need to get another spring.

Yup. There's also a small ball bearing in the top of the switch which likes to pop out at light speed. I hate the rear defrost switch with a passion.

Yeah, i got you covered with a pic on that :)

Yeah, i agree, those buttons are VERY sensitive, luckily i didn't snap any of the buttons loose either, but i agree, it took me several hours to take apart heh.

Yeah i hate that damn button too. It took me 45 mins to figure out how to slide that rear defogger button out of the hvac control unit lol. I'm going to string in some microbulbs from radioshack and use the bulb covers from the link bigacuralvr provided and see how they turn out. 3mm 360degrees would be nice, but i didn't find any on superbrightleds.com either.

Oh, i was going to mention, could it have been possible to slightly angle the illumination LED for the rear defrogger to face foward more?

I will post a pic up shortly of the red led's i used (from your write up) of the gauge clusters, they look really nice. However, i wasn't able to use the brake led...when my ebrake was disengaged, it still slightly illuminated. Also, that amber bulb for the fuel light wouldn't work either. It always stayed on. If i turned the bulb around, it obviously didn't work since it was an LED. I just kept the regular bulb instead. Maybe I have a 92-93 cluster, and you have 90-91 cluster :shrug:

Bryan
 

toayoztan

Moderator
Here are some pics of the LED's used from Simba's write up for the gauge cluster. I tried to best capture the intensity of the LED's, but..well, it's hard for me lol. So, two notes to keep in mind - 1) They are slightly brighter, give off more of a glow, on the highest intensity/illumination setting in person, and 2) They are actually a slightly deeper red in person than what you see in the pics. Now, on to the pics!

This pic is a general pic showing the cluster. Again, the intensity is slightly brighter in person. The needles are more visible and glow nicer in person. But his gives you an idea of the eveneness of the color across the cluster:
redledcluster001pf3.jpg


Here's another angle of the cluster and shows the key halo. I know the halo looks orangish in the pic..but trust me, it's not. And i'm anal when it comes to color match perfection.
redledcluster008hd2.jpg


Upclose view of the speedometer.
redledcluster010df9.jpg


Upclose view of the misc gauges. Again, the needles are more visible/glow brighter in person.
redledcluster025ih9.jpg


Another view of the speedometer.
redledcluster026oo8.jpg


Here's a shot of the key halo. The camera drew out the intensity of the bulb and the bright spots, but in person, the color and brightness is more even and red (close like the upper right corner of that halo in the pic). This gives you an idea of how bright the halo can look and that you are able to change the color of it.
redledcluster032ak1.jpg


I should have better pics when i get the HVAC completed with nicer red illumination. These pics were taken in a hurry last night. Enjoy!

Bryan
 

Simba

New member
toayoztan":3minnqj7 said:
3mm 360degrees would be nice, but i didn't find any on superbrightleds.com either.

I found some ~120 degree 3mm white LEDs which I'm going to try next. They should do the job. Else, I may drill the light holes out for a 5mm LED.

I should note that it's considerably easier to find 120+ degree 3mm LEDs in just about every color except white. But I had to be special. :twisted:

Oh, i was going to mention, could it have been possible to slightly angle the illumination LED for the rear defrogger to face foward more?

Yes, but you need to hook it up and make certain you have the polarity correct on the illumination LED, else you'll be screwed if you have to turn it around. I'm going to bend the new 3mm LED 90 degrees or so when they come in for that bulb.

Hopefully I can get everything as bright as the fog light switch, then turn the intensity down so it's all a nice white glow.
 

Qlynxer

New member
Here are some quick pictures i snapped of my 165 gauge cluster. I replaced all eight 194 bulbs and all eight 74 bulbs as well. Of the eight larger 194 bulbs, four of them are for background lighting, two for the signals, one highbeam and one low fuel warning light. For the smaller lights i think half of them are red and the other half are amber. The smaller bulbs were a pita since they dont fit the housing and some material had to be sanded away and some of them don't work well like the defogger light, and the hand brake indicator is always dimly lit. The only ones that seemed to really make a diffence were the four background bulbs. If were to do it agin i would just replace those four. I tried the green bulbs but they turned out ricey because the were just too damn green compared to stock which is a more mellow shade of green, looked like i was staring at a Klingon tactical display.


[img=http://img293.imageshack.us/img293/8468/pict0466af1.th.jpg]

in the picturse, the lighting looks a bit brighter then it does in person, but still a huge improvement over stock. I order from superbrightled and they ship very fast.

Quan L
 

Simba

New member
justjoe":27i98o8r said:
The only real mystery is the HVAC illumination..

To which I have found these:

Those are normal narrow-focus #74 size leds in a twist base. The HVAC doesn't use #74 bulbs, it uses smaller bulbs.
 

justjoe

New member
Simba":u9mzj0of said:
justjoe":u9mzj0of said:
The only real mystery is the HVAC illumination..

To which I have found these:

Those are normal narrow-focus #74 size leds in a twist base. The HVAC doesn't use #74 bulbs, it uses smaller bulbs.

Oh.. Please do not look at the 74's (both on that page) They are too expensive anyhow..
http://autolumination.com/74.htm
Just look at the Neo Wedge ones.. for the Actual illumination of the HVAC.
 

justjoe

New member
Let me shed a little more light on the HVAC illumination (sorry for the pun)

HVAC illunination incadescent bulbs come in at least 3 sizes:

Dimensions:
small (TS) - used for HVAC illumination
base diam-7.6mm
base thick-2mm
bulb-4.5mm
neck-4.75mm
height-10.5mm~11.5mm

medium (TS) - used for defrost illumination
base diam-7.6mm
base thick-2.3mm
bulb-3.5mm
neck-4.6mm
height-10mm

large (TSD V-2) - used for defrost ON
base diam-7.6mm
base thick-2mm
bulb-4.5mm
neck-6mm
height-12.5mm

It looks like maybe the LED ones from these Online stores will only with the Defrost or the Fog maybe.. ?? no tellin. Hardly even work dorkin with, if I can only use it for maybe 2 things.. =( I would rather Solder the darned things up.. since I got my tiny 1k resistors..=)

I saw that Simba went and wired up some LED's.. for his defrost and fogs.. Did that 45 degree one work OK?

Now I just gotta figure out if those 360-degree bulbs from superbrightLEDs.com will work in red.. and still fit right..
a T1-3/4 is 5mm
and T-1 is 3mm, right?
I know they are diffused and not clear..
http://www.superbrightleds.com/leds.htm

I am sorry if this is TOO much info..
Why does this have to be soo confusing?

Also, Why did you guys take apart the Defrost switch? You can get to the lights without taking everything apart.

So, Simba.. where can we find some good 360 degree 3mm LED's???
 

toayoztan

Moderator
The dimensions for the bulbs you gave is for the HVAC of a 1990-91.

Well, i figured out that defroster switch the second time through heh. I think what we're both saying is that it's a pain in the ass to get the defrost unit out, period.

Bryan
 

Simba

New member
justjoe":2xa72kbb said:
It looks like maybe the LED ones from these Online stores will only with the Defrost or the Fog maybe.. ??

They won't work anywhere, as they're not 180+ degree lights. The only place they'd work would be in the gauge cluster, though it's cheaper to just make your own with #74 wedge LEDs.

I saw that Simba went and wired up some LED's.. for his defrost and fogs.. Did that 45 degree one work OK?

The 3mm works decently, but not great. I have some ~120 degree LEDs on order which should work better.

Now I just gotta figure out if those 360-degree bulbs from superbrightLEDs.com will work in red.. and still fit right..

The 5mm 360 degree LEDs work fine in the large #74 size holders, which so far as HVAC and dash controls go, work for the fog light switch illumination, the "on" illumination for the defrost switch, and the "on" illumination for the AC switch. They won't fit anywhere else, and yes, the red one works in the #74 holders, I'm using one for my defrost "on".

Also, Why did you guys take apart the Defrost switch? You can get to the lights without taking everything apart.

For the hell of it, as well as to re-grease the contacts and make sure the LED clearances inside were good. Taking the switch itself apart is easy. Taking it out of the cluster is a complete PITA.

So, Simba.. where can we find some good 360 degree 3mm LED's???

You can't, at least so far as I've found. The closest is a 120 degree 3mm which I found from a bulk supplier. I had to order 100 of them to get any.

If you're going with a color other than white, you're probably better off staying with a normal bulb with a color condom until someone brings out a 3mm 180+ degree LED.
 
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