The bulbs behind my Tachometer burned out a while ago and I decided I would replace them with LEDs. I also replaced the ones behind the speedometer as well. Overall I probably spent more on this project than normal, but I bought a few miscellaneous items. My car is a 1992 Nissan Pick-up.
NOTE: This may or may not work for you. But it doesn't hurt to look and see if you really want to do it.
-Standard Phillips Screwdriver
-Precision Screwdriver Set
-Vise Grip Pliers*
-4 Ultra High Brightness White (Or color of your choice) LEDs. These can be swapped for almost anything really. The brighter the better though.
-Resistors. Varies based on LEDs.
EDIT: Sorry for not having any before pictures. I took it apart before I knew I could replace them and then I just wanted to get it done.
Step 1: Disassemble!
My favorite part! I love taking things apart. I apologize for not having any pictures, but every car is different. I also disconnected a few things to make the back of the instrument panel easier to access.
Step 2: Locate the Lights.
I located the bulbs that burned out as well as the ones that were still good. I could have replaced more than what I did, but these are used most often. I analyzed how they worked and where power was coming from. They have two metal pieces that touch the copper of the circuit board on either sides of the holes that send power to the bulbs.
Step 3: Test for Voltage.
This step requires a multimeter. When I first did it I tested with my car off and got 11.78 volts. I tested with my car on and got 13.69 volts. I decided to round up and use 14 volts as my base. I only tested with it off, because I didn't think about testing with it on until ten minutes later. Would have been bad if I didn't test with it on.
Step 4: Take an Environmentally Friendly Trip to Your Local Electronics Store.
Or you could: borrow a car, put your car back together, order online, etc. Whatever you want to do to get where you need to go. Once there I started looking around for what I needed and found some 10mm high brightness LEDs. They are 3.5-3.8v, 20ma, and 28,500mcd. Perfect.
When I was there I used Opera on my phone to go to Ledcalc.com
and calculate what kind of resistors I would be needing. After putting in my inputs the resistor I would be needing is a 560ohm 1/4watt resistor.
Radioshack didn't have that specific resistor, so I just got a package of 470 and a package of 100 to hook together.
Step 5: More Testing!
Woo! I hooked an LED with the resistors with alligator clips and tested it with my car and...IT WORKS!!
I was so totally excited about it working I thought I would stick it in the hole to see how the LED would look from the other side. My lights shut off. I blew a fuse! I didn't know what it was at the time, checked all my fuses and they all looked OK. I was wrong though, but I didn't take anything apart so I was OK in the end. Had to buy fuses though.
So please make a note not to touch the two sides. Really slows things down.
Step 6: Solder!
Time to solder. I soldered the resistors to the LEDs and put some heat shrink over it. I removed the bulbs from their plastic casings and had to use a little force to get the LED in, but it was all good. Didn't break on anything.
Next I soldered LED to the plastic thing. It was a bit challenging. I had to use sandpaper on the points I was soldering to and I melted the plastic a little bit, but it all worked out.
I tested it one last time to make sure my solder points worked. I had to re-do a couple to make them work right. I installed them and I was all done. Looks great too!
Step 7: Bonus!
This is somewhat of a bonus to myself. Might aid others as well. My panel had these blue cap like things over the LEDs that I was just going to keep there, but they kept falling cause the plastic around them broke a little bit. So as an alternative I found plastic caps from water bottles/sports worked perfectly. They fit nice and snug.
Also the LEDs were a bit too focused to just leave them uncovered. I wanted it to smooth, so I painted the top of the caps white.
Step 8: Finished!
I am extremely proud of what I was able to accomplish. What with my basic knowledge of soldering and electricity. It looks great. You can't see them on during the day, but that's not what matters. I was also surprised to find my dimmer still works and dims the LEDs.
All in all I probably spent about $30-40, but that's because I bought a multimeter, shrink wrap, and alligator clips. If I had already had those items it would have been about $7-8.
If I left anything out or you have questions please let me know in the comments. Thank you for viewing my Instructable!