I recently bought a high mileage 2004 Dodge Ram pickup truck and in addition to swapping out the old and nasty headlights I decided to also replace the standard dashboard light bulbs, many of which had burned out, with LEDs. Most of the lights could be swapped easily, using direct replacement parts from sources like superbrightleds.com but the one behind the headlight switch assembly was a bit trickier. In this Instructable I'll show you how I solved the problem and perhaps you can use a similar technique on your vehicle.
To perform the bulb swap you'll need:
- LED designed for a 12 volt DC application
- Soldering tools
- Basic hand tools (screwdriver, etc.) depending on your vehicle
NOTE: This Instructable involves working with your vehicle's electrical system. Serious damage can occur if you mess up the connections and create a short. If possible you should disconnect your negative battery cable whenever working on the electrical wiring in your car.
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Step 1: Access the Dashboard Component
Most modern vehicles use modular components that can be removed relatively easily. The first step is to figure out how to access the component. If it is not immediately obvious (since manufacturers are quite clever in concealing screws and other connectors) I would highly recommend getting your hands on a repair manual for your vehicle as they typically include detailed instructions on how to access various components. A simple web search (for example, "2004 dodge ram repair manual pdf") should return numerous results. I downloaded a copy for my truck (all 4600 pages worth!) for less than 10 dollars.
In my case the dashboard panel holding the switch assembly was only held in place by spring clips. After first removing the lower dashboard cover panel (just below the steering column), which was secured by two screws, I was able to simply pry off the dashboard panel with just a little hand pressure.
The headlight switch assembly is attached by a 8-pin connector and is held in place by a plastic tab. To remove the connector, press down on the tab and then pull gently on the connector until it slides off.
Once disconnected from the wiring harness, the switch assembly can be separated from the dashboard panel by removing three screws.
Step 2: Locate and Remove the Burned Out Bulb
To access the bulb I had to remove the rear cover from the headlight switch assembly by removing 4 screws.
NOTE: in my case the internal parts, including the dimmer wheel, were held in my pressure from the cover plate. Be careful when disassembling components like this as the parts my fall out and you'll be left wondering how they go back in!
Once the cover was removed I was able to access the circuit board containing the burned out bulb, which was attached to two small solder pads. I was able to remove the bulb by hand just by wiggling it back and forth. You may need to heat the pads with your soldering iron to remove them if your vehicle features a similar arrangement.
Step 3: Select a Replacement LED
Superbrightleds.com is a great web site for ordering bulb replacements because you can simply enter your vehicle make and model and get a list of compatible LEDs, most of which are designed to fit the factory connectors. However, they did not offer an option for this particular bulb so I had to guess at which one would work based on the size of the original bulb. I decided to go with 3mm (T-1) NEOx LED in blue because if was approximately the same size as the original bulb and rated for 9-14.8 volts DC.
Step 4: Install and Test the LED
After receiving the LED I noticed that the base was not exactly the same size as the original bulb, meaning it did not sit squarely on the two solder pads on the circuit board. Fortunately for me the pads were connected to through holes in the board. After carefully unwinding the lead wires from the base i inserted them through the holes in the circuit board and bent them back on the other side to hold the LED and its base in place.
NOTE: Unlike standard incandescent bulbs, LEDs will only work when installed with the correct polarity (electrical positive and negative). Therefore I would highly recommend testing the installation by reassembling the switch component and reconnecting it to the wiring harness BEFORE soldering it in place. If the LED doesn't work as expected, disassemble the component and swap the LED leads in the circuit board and try again.
Step 5: Reassemble and Reinstall the Component
Once you have verified that the LED works, solder it in place and reassemble the switch component. Reinstall it in the dashboard by reversing the order of the disassembly steps. If you disconnected the battery negative lead go ahead and reattach it. The LED replacement should look awesome and complement the dashboard lighting.