Ok so recently I've changed my 4 main bulbs in the cluster to blue bulbs. Not LED, but they look a little cooler than the dull yellow. Btw, this is a 98 accord 4 cyl. I tried to wire up a LED that I bought at radioshack to the odometer neo-wedge, quarter turn fitting. Needless to say, it didn't work. But now NO bulb will work for my odometer. I even put a brand new stock neowedge toshiba v-2 in it with a new bulb, and nothing. All other lights work on cluster, and fuses are all good. Did I short something? How do I check? How do I FIX? Same scenario with the clock light. Wired up a LED to the neo-wedge quarter twist, turn the car on and POP! There went that LED, lmao. I realized after it was a 5V led, and 12V blew it. But same thing, now NO neowedge or bulb works in there... any suggestions??? Or am I looking @ a new cluster and clock board?? Thanks in advance..

 

This one might take a bit of research to figure out.
Anyone knows the answer? Jump in if you do!

 

when installing LED's in place of incandescent bulbs, you need to include a drop resistor in series with the LED. the resistor reduces the voltage for the LED - since most LED's are 2.1-3.4VDC drop across them. The resistor is sized to control the amount of current through the LED since each LED has a current rating also.

most LED's T3 or T5 will operate very well with 20mA of current (verify with the LED datasheet). to size the resistor you need to know the voltage drop of the LED and the rated current (for whatever life you want from it since more current = shorter life).

the calculation goes like this:

Vs = Source Voltage (max output from alt) = 14.4 VDC
Vled = LED Voltage Drop = 2.5 VDC for this example
Vdrop = Resulting voltage across resistor
Rdrop = Drop Resistor (to set up voltage drop) = what we are solving for
Iled = LED current = 20mA for this example

Vdrop = Vs - Vled = 14.4 - 2.5 = 11.9 VDC
Vdrop = Iled x Rdrop
Rdrop = Vdrop / Iled = 11.9 / .02
Rdrop = 595 ohms

Choose the closest standard resistor value, 620 ohms is the closest larger size for more life and 560 ohms is the closest smaller size for more brightness. Note that as supply voltage drops, the LED will reduce in brightness. To prevent this you'll need to install a voltage regulator and base your calculations on the new voltage. Note that a voltage regulator only works if the supply voltage is at least 2VDC higher than the output. So, choose a 9VDC regulator - LM7809 and follow the circuit on the datasheet, and repeat the calc above with Vs = 9 (= 330 ohms given the assumed drop and current).

 

as far as your issue with non-working bulbs - when you sent too much current through the LED, it could have easily damaged a component on the board. oops. lesson learned here - one you won't soon forget.

next time, do some internet searching before tackling an electrical project when you aren't familiar with electronics. start with this:
http://www.bcae1.com/led.htm
- this link includes a calculator for the above math i outlined.

the only LED's that can be wired directly to 12V already have a resistor wired in series with them.

the real tricky part is that when putting LED's in the instrument cluster, you need to use a surface mount device (SMD) resistor so it fits on the twist base.