Turn Signal + Brights LED Indicator Upgrade

[yertnamreg]

I'm not a big fan of the incandescent bulbs used in our indicator display. I did a little digging and they are a standard 5mm size that you can also get LEDs in. The problem with LEDs is they aren't designed to handle the voltages these indicator lights use.

Most of the indicator bulbs in our dash are 24V. I still haven't found a good solution to replace these. However the turn signals and brights use 12V bulbs and there is a company out there making LEDs with integrated resistors for applications like this.

Parts:
Green LEDs
Blue LEDs
Spacers (I honestly would use ones that are slightly longer if I had to do this again)

Here's what I did:

1) Pull the indicator unit. Just pop out the four bolts on the front and the unit will lift out and let you unplug it.
2) Use a flat head screw driver to unscrew the four spring loaded screws on the back.
3) Pull the bulbs out for the two turn signals and the brights in the middle.
4) Insert the new LEDs. Polarity is important on these. The big trace at the top of the board is actually the ground. If you look at the board as it's installed in the dash the LED orientation is:
Left turn -> Flat side of LED to the right
Brights -> Flat side of LEDs to the left
Right Turn -> Flat side of LEDs to the left
5) Put it all back together and test it in the truck

Its not a big modification, but it makes these indicators a lot more visible. FYI I chose to use blue for the brights even though the mask in the housing is green. The blue light still shines through nicely though.

Before:


Housing when you take it apart:


LED Install:


After:


I'm still tweaking some things and will update when the install is more final, but wanted to share

 

[coachgeo]

so since they are all clear in OEM setup...... then we could just go all clear in LED if we wanted?

in reading your description about LED polarity.... having never held one in my hand up close have no clue what you mean by "flat" etc. for others like myself..... here is a vid. that may help

https://www.youtube.com/watch?v=kRqd2Q5Hdnk

 

[yertnamreg]

That's correct. Here's a link to the full listing of the 12V LEDs that will fit
https://www.digikey.com/products/en...27&quantity=0&ColumnSort=0&page=1&pageSize=25

You should see a "white" one in there. Keep in mind this only works for the three indicators listed.

 

[coachgeo]

That's correct. Here's a link to the full listing of the 12V LEDs that will fit.... [...link...] Keep in mind this only works for the three indicators listed.

??? so the others are not interchangeable with LED's??

 

[yertnamreg]

Not as easily as the turn signal and bright indicators. The lighting on the truck is a 12V system so these spots in the indicator panel are also powered with 12V. Most of the other systems on the truck are 24V, so the indicator lights for these use 24V.

Like incandescent bulbs, LEDs are designed to have a certain amount of power going through them. Unlike incandescent bulbs, LEDs have almost no resistance and look like a dead short on their own. This is why you'll almost aways see a resistor in series with an LED. The LED limits the current going through it and thus regulates the power being dissipated in the LED.

The LEDs I linked are special in that they have a resistor inside them that is sized appropriately to power the LED directly off 12V. No one makes an LED like this for 24V that I've been able to find. It is possible to cut the board and add resistors, but it would be very involved and not practical as a mod for general consumption.

 

[coachgeo]

Not as easily as the turn signal and bright indicators. The lighting on the truck is a 12V system so these spots in the indicator panel are also powered with 12V. Most of the other systems on the truck are 24V, so the indicator lights for these use 24V......

ahhh. now that makes since.... its not a bulb thing.... but input voltage thing.

 

[Awesomeness]

Is there a single 24v input to that board, that perhaps you could break one of the circuit traces and install a resistor across the break to drop it to 12V?

Or, it looks like there are a bunch of resistors on that second board behind the lights. Could those already be dropping the voltages to those lights?

 

[yertnamreg]

Thanks for getting me thinking!

The place to start is looking at electric schematic page 13 of 40


The things you're thinking of are actually the diodes in this pic. That said there very well may be a way to add one or two resistors to enable us to use these LEDs. The problem I saw is that the lamp/LED board has the same copper on both sides and is soldered directly to the bottom board. This makes cutting traces and modifying the board difficult. I haven't looked at the bottom board as closely but maybe, just maybe we catch at break there.