LED Dashboard Bulb Replacement

Intro: LED Dashboard Bulb Replacement

Simple replacement fix for dashboard lamps. LED's should out live the vehicle so should never need to replace them again.
you need;
- straw hat 1/2 watt leds (one for each bulb) (eBay has thousands to chose from complete with resisters)
- resisters for the leds to operate on 12-13.5 volts
- heat shrink tubing (to make it neat and tidy
- soldering iron and solder
- some thin wire (i use telephone cable)
- hot glue gun and glue
- tools to remove the dash panel

this is really easy to do and has vastly improved the legibility of my dash

STEP 1: Remove the Dash Panel

So firstly remove the panel and disassemble it so you can connect to the electrical tracks

STEP 2: Assemble the LED's

So next we need to solder the resister to the LED, it does not matter which leg you use.
Cover the resister and leg with heat shrink tubing, leaving a little wire exposed to connect to.

STEP 3: Place the LED's

Put the LED in the hole the orignal bulb sat in. It should sit in there quite nicely. if the hole is to big, wrap electical tape aroud the base of the led till it fits.
Hot glue the LED into place. let the glue cool completely before tugging at the LED or it may come out.

STEP 4: "more Power Scotty!!"

so we need to make an electrical connection to the panel. some will have a printed circuit board in them and others metal tracks fitted into the panel. mine is the latter.
you may need to clean the tracks to solder a good connection.
pass the wire through to the back of the unit to connect the LED's

STEP 5: Test the Polarity of the Wires

before we solder up the last connection to the LED's we need to check the polarity of the supply tracks, as LED's are polarity specific.
a quick reconnection to the vehicle and test the wire's onto the LED's and remember which way round they go.

STEP 6: Solder Up the Final Connections

Make sure that the connections are insulated and won't get trapped by anything.
reassemble the panel and refit back into the vehicle.
stand back and admire your work.
start planning your next project!!

Comments

[pfred2]

Some things you may wish to add to your article.

What diameter LED you used. The ones you used seem to come in 5 and 8mm sizes.

What Ohm value resistor you used. You stated the correct Watt range but never the resistance value.

A more sure fire way to determine LED polarity. One easy way is seeing which lead is shorter. The shorter one is the cathode.

With apologies to Will:

To big, or not too big, that is the hole question!

http://www.educationbug.org/a/to-vs--too.html

Personally I like cars better after all their dash lights burn out :)

[professor sparky]

hi!
i use 8mm LED's which i buy with the correct resisters to run on 12volts, its cheaper than buying them seperatly and easier for those who dont know how to work resistance values. Mine are 2w 100ohm resisters.

R = (VS - VL) / I
VS = supply voltage
VL = LED voltage (usually 2V, but 4V for blue and white LEDs)
I = LED current (e.g. 10mA = 0.01A, or 20mA = 0.02A)

The polarity you need to check is the dash unit as the tracks are not normaly marked. sorry if that was not clear.

Perhaps i will do an instructable on basic LED science

[pfred2]

No it wasn't clear to me when what you said was, "before we solder up the last connection to the LED's we need to check the polarity as LED's are polarity specific."  Check the polarity of what? The last thing you mentioned was LED. I am a contextual reader. Rereading it knowing the polarity you mean is the supply polarity it all makes sense. It didn't the first time I read through it though. Well, it did make sense to me, just not what you meant.


I'd like to see how the math is figured for a 100 Ohm resistor running an LED off 12 volts. So write that LED science article! Are your LEDs 80ma? The ones I was looking at online seemed to be about 20ma. Yours must be really bright!

[professor sparky]

hi, the LED's are 3v forward voltage, 100ma forward current.
yes they are realy bright!!

search eBay for "strawhat led 8mm"

the ones i use are 0.5w

[pfred2]

I bet they are bright. Have you measured your current draw with a multimeter? What the hey it is working for you good luck!