How to: 2004 Dodge Ram HVAC Bulb Replacment


Shut Up Stupid
May 21, 2009
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Titusville FL
soldering required!!! haha

How To Change The Dash Lights
In a 06-08 Ram
From pale blue green
To Awesome LED Blue

This How-To will explain how to change the lighting in the following parts in an 06-08 Ram:
• Cluster
• Headlight Switch
• 4x4 Switch
• HVAC Controls
• Rear Power Sliding Window Switch
• Overhead Console
• Stock Radio (AM/FM/Sirus/Single Disc CD)
• Dome Light
• Map Lights

This article assumes you know how to remove the radio bezel, cluster bezel, and cluster. Also, to go all the way with this mod, you should have a decent comfort level with electronics and soldering techniques.

Background Information
I did this all in blue in my 08 Quad Cam Big Horn Ram 1500. I prefer consistency, so I went with all blue. It should be noted that the red highlights in the HVAC control, and the redline indicators on the stock (white) cluster disappear and do not appear to be lit. Others have gone with white LEDs to solve this problem. Other colors will not work well.
Here’s a quick physics lesson on light. A colored overlay or lens works by selectively blocking out wavelengths of light to only let certain wavelengths pass thru. A blue overlay will let only light around 450-495nm thru. This makes the light appear blue. Conversely, a red filter passes light in the 620-750nm range.
Normal filament based incandescent bulbs emit light at all wavelengths in the visible spectrum (380-750nm). LED bulbs work differently. LEDs emit only a very specific wavelength of light. For example a blue LED typically emits light only at 470nm. No other wavelengths are produced. For this reason, if you put a blue LED behind a red film, you will see no light at all through the film. The one exception is white LEDs. They work a bit differently than the colored LEDs. There really is no such a thing as a white LED. White LEDs are actually blue LEDs with a phosphor coating that glows brightly when excited by the blue light. This causes other wavelengths to be emitted making the white LED look white and not blue.
I mention this, because there are various colored films in the dash of the truck. Some parts have blue film as part of the overlay. Other parts have blue caps on the bulbs, and no blue film on the face. There are two parts with red films as part of the overlay, the redline marks on the cluster, and the hot side of the temp control. These will not light with blue LEDs. I find it to be just fine. Others have subsequently solved the problem by using white LEDs instead of blue. If you try to use colors other than blue or white, you will have inconsistent results from part to part in your dash.
I did my dome and map lights in Cool White. They are very bright, and look great with the blue dash. Since the lenses on these parts are clear, you can do these in any color you like.
I got all of my LED bulbs from . These guys are great to work with, and ship orders very fast. (I hope I get a discount on my next order for all the advertizing I’m doing for them)

Bill of Materials
Use Quantity Part Color Unit Cost Total Cost
Cluster 5 B8.5D Blue 1.59 7.95
HVAC 3 B8.5D Blue 1.59 4.77
Headlight Switch 1 WLED-R-x Blue 1.39 1.39
4x4 Switch 1 WLED-X Blue 1.39 1.39
RSW Switch 1 RL3-B2030 Blue 0.67 0.67
Overhead Console 3 Neo-B Blue 1.29 1.29
Radio 10 RL3-B2030 Blue 0.67 6.70
Dome Light 1 4210-CWHP6 Cool White 14.95 14.95
Map Lights 2 4210-CWHP6 Cool White 14.95 29.90 TOTAL 69.01

I also bought 1 strip of WFLS-B300 which is waterproof flexible cuttable LED strips. Most of that went under the truck for running board lights, but 6" or so is over the cup holders and 2 14” sections light up the front floor from under the dash when the doors are open.

You’ll also need:

• Wax paper
• 1 Sheet of #74 “Night Blue” RoscoLux Gel (get this from theatrical lighting supply company)
• 11 470Ω 1/8 watt resistors
• 2 100Ω 1 watt resistors

• Soldering Iron
• Electronics Vise, or other parts holding device.
• Pliers
• Philips Screwdriver
• Torx Screwdrivers
• Very small flat blade screwdrivers. (tweekers)
• Small Wire Cutters
• X-Acto knife
Also read the radio section here for other tools you might need if you go all out with that mod.


Unlike the 02-05 cluster, the 06-08 has only 5 lights in it. And they are all exposed on the backside. No modification to the bases or cluster is required. This is a plug and play swap. No need to disassemble the cluster or needles either. There is a small bit of hot-spotting, but it's not that noticeable if you're not looking for it. Simply Remove the cluster and flip it over. Each of the 5 bulbs will come out with a quarter turn. Put the new ones in their place. NOTE: LEDs are polarized. Plug it all in and check the bulbs to make sure they work before reassembling the dash. If a bulb doesn’t work, pull it out, turn it 180° and put it back in. That’s all that’s to it with the cluster.
NOTE, if you start your truck without all 3 of the harnesses plugged into the cluster, you’ll get a check engine light on for a few days. It’ll go away on its own.
If you want to change the gear shift and odometer displays to closer match your new blue LEDs, it’s not too difficult. You’ll need to disassemble the cluster to do this. You’ll want to take it to the workbench and get it on a lint free cloth to keep it from scratches and dust. Get it disassembled to the point where you can touch the printed gauge face. You do not need to remove the needles. The gauge face is attached to the plastic housing with a spray adhesive. Get two small pieces of wax paper a bit wider than the odometer window and long enough to extend from the top of the odometer and protrude an inch or so beyond the bottom of the housing. Also cut a piece of the #74 RoscoLux Gel sheet the same size.
What you need to do now is start to gently pry the face away from the housing in the area around the odometer. Use the x-acto knife to cut at the stringy adhesive as you pry. Sandwich the two pieces of wax paper together and start to work them into the opening you make. You should be able to see them through the odometer window. Pull the top piece of wax paper out enough to expose the odometer window. The wax paper creates a non-sticky slot to slide in the gel. It also keeps it clean and free of adhesive as you’re working. Now, start to slide the blue gel in between the wax paper sheets. Get it lined up with the odometer window. Once it’s in place, pull out the back piece of wax paper, and push it down. It should get stuck in place from the adhesive. Then pull out the other wax paper piece. And press down on the gauge face to get it all stuck together. Once this is done, use the knife to trim the edge of the film to the profile of the cluster face. You can reassemble the cluster and put it back in the truck now.

HVAC Control:
There's 3 lights in this module. Use the B8.5Ds again here. You’ll need a bit more creativity here though. You’ll have to disassemble this module. Remove it from the radio bezel with the 4 screws. Then take off the knobs. Then remove the screws and separate the back from the housing. Inside you’ll see a clear plastic light pipe. This guides the light from the bulbs to the face of the display. Make a piece of doubled up wax paper to fit the entire inside of the front face. Poke the 3 holes for the knob shafts in the paper. Slide this paper loosely between the light pipe and the face of the display. It should be closer to the cup like parts of the light-pipe than it is to the face. Reassemble and you’ll be all good.

4x4 switch and Headlight switch:
The procedure for both the 4x4 switch and headlight switch is very similar. This part is NOT PLUG AND PLAY. Board level soldering experience is very helpful here. Remove both of these from the dash and bring them to the workbench. You'll need a electronics vise and good soldering iron for this part. First, remove the screws from the back side of the module. Then holding it with the buttons/knob facing down, remove the back of the assembly. You'll be left with the back half of the assembly with the circuit board in it all full of dielectric grease. On both modules you'll see a small bulb in a square white housing.
This is the point of no return! Unless you have a hot air rework station (and most of us don’t) Grab the white part with a pair of pliers and gently rock it back and forth until it breaks free. If you do have the rework station, you’ll already know what to do here. This will leave you with two solder pads underneath where the bulb housing was.
I used WLED-X LEDs for this part. You need to remove the LED, resistor, and diode from the base. You'll take this WLED bulb and straighten the leads out. Then using a pair of pliers, gently squeeze the base where it meets the LED itself. Do this a few times, from all sides, and it'll break the glue holding it together. Then you can grab the LED and pull it straight out of the base. Leave the resistor and diode attached to the LED, but trim the leads to about 3/16". Bend the remaining tails 90 degrees toward each side. you'll solder these tails to the pads on the PCB that you exposed earlier from under the old lamp housing. Polarity does matter. I can't remember which way each was supposed to be. Plug in the board to the truck harness and test before doing all the reassembly to make sure you have the polarity correct. If you get it backwards, just pull it back apart and reverse the contacts.

Rear Sliding Window Switch
This is the hardest to disassemble. I had a very hard time getting the switch out of its bezel, and then again, to get the switch itself apart. You have to be careful to not break the plastic tabs. It's just a matter of wedging in little screwdrivers until you get it to pop out of the bezel. Then repeat again to get the switch itself open.
Once it's open you'll see a bulb soldered to two contacts in the center of the switch. Unsolder this bulb to remove it.
Use one of the 3mm bare LEDs for this. Solder a 470 Ω to the shorter leg of this LED. Clip both the resistor and LED lead to about 3/16” and solder them together.
Again, polarity matters, but this time you don’t have a diode to protect the LED. Don’t get this one backwards. Use a multi-meter to check the polarity of the contacts. You can plug it in to the harness and read the DC voltage across the two contacts. If it reads negative voltage, swap the test leads on the contacts. The contact with your black multi-meter probe on it is the contact that gets the resistor side of the LED. Now after you've tested everything for proper polarity, put it back together.

Overhead Console:
Use a small tip screwdriver and pry out the map light lenses. Remove the map light bulbs. There are two torx screws to remove. Once these are out, the rest of the assembly will pop off. You’ll see the 3 bulbs in the back of the black electronics module. Pull out the bulbs with a quarter turn. The 3 Neo bulbs go in here. Again, test for proper polarity before reassembling. Now remove the black electronics module from the bezel. Carefully remove the smoked plastic lens over the computer display (FYI, this display is a Vacuum Fluorescent Display or VFD). Cut a strip of the RoscoLux #74 gel to the same size of the glass face of the VFD. Give the face of the VFD a good cleaning with a lint free cloth. Don’t use any liquid cleaner. Next use some good quality clear tape, and tape the gel in place. Reassemble the module, then put it back in the bezel and put it back up.
I also switched the festoon bulbs to LEDs. The 6 High Power LED bulbs from do a very nice job in the map and dome lights. Only one initial problem though. When the truck is off, you can’t tap the light and have it come on. It works with the door open, and if you tap it while running, but not when the key isn’t in the ignition. To overcome this, solder the 100Ω resistor across the ends of the bulb. If you use a resistor with too low of a wattage rating, it will buzz when the lights dim. It stopped buzzing at 1 watt in mine. Make sure this resistor floats free in the housing, and don’t let it touch the plastic. It gets a bit hot, which is normal, but you don’t want melting plastic. It actually gets about just as hot as the original bulb that was in there. Now you can put the lenses back in and you’re done with the overhead.

Dome Light
This part is simple Plug and Play. It uses the same bulb as the map lights. No resistor is needed because there is no manual switch to press. Polarity doesn’t matter with these HP6 style bulbs.


First of all, this is way too much work to put into a stock radio. It’s probably easier to just replace the radio with one that already has blue LED lighting. It did however make a good project for me, and turned out very nice. If you do want to go ahead though, here’s the process.
First, remove the screws that hold in the radio. You will see 4 additional gold colored T10 torx screws. Remove these. Slide the radio a bit forward and you’ll see tabs on the top and bottom of the radio face. Gently pry these tabs and the radio face will pop off. There will be a gray ribbon cable attaching the face to the main body of the radio. Pull this ribbon from the main unit and the face will be free. Pull off the knobs. There will be seven T9 torx screws that fasten the board to the housing. Remove these and separate the parts.
Now prep your new LEDs. You’re going to use the 3mm LEDs for this. I originally started with a different LED and method, but on a second attempt, I redid it with these, and it worked much better. You’ll need 10 LEDs and 10 470Ω 1/8w resistors. It’s important to know that there is very little room to work inside of the radio face. You’re going to need to do all of this as small as possible.
I took an extra step a bit later in the process when I did it, but it’s best to do it at this point if you’re going to do it. In order to get the LED to light the face more evenly, I sanded down the top of the LED so that it’s flat. Using a piece of 400 grit sandpaper, rub the led so that you flatten the top. Don’t go too far, just take off the dome.
Cut the short lead of each LED to about 1/8” long. Cut one leg of each resistor the same length. Solder the short leg of the resistor to the short leg of the LED. Once it cools, it’s time for some creative bending.
Bend the lead with the resistor 90° outward. Now bend the long end of the resistor down and back under itself. It should be going back toward the LED, and cross the other LED lead. Now trim this bent leg of the resistor so that it stops where the lead comes out of the LED.
Take the other lead of the LED, and make a bend 90° away from the resistor in such a fashion that it makes a foot facing away from the resistor. Trim this to 1/8” after the bend.
It should look something like this:
| |_w_
_| ____|

On the radio board you’ll see 10 SMT bulbs with blue condoms on the board. It’s these that’ll get replaced with LEDs. Before removing these, you’ll want to mark the polarity of each one. You’ll need to do this live. Plug the ribbon cable back into the radio, turn on the truck, and turn on the headlights. Take a spare LED and use it like a pair of tweezers to touch the contacts on both sides of each bulb. When the LED lights up, the negative side of the bulb is side that touches the short leg of the LED. Use a sharpie and make a mark on the board for the negative side.
After the polarity is marked, it’s time to remove the old bulbs. Using a similar technique to the headlight switch, grab the base of each bulb, and rock it until it breaks free from the board. You can now begin to solder on the new LED assemblies you made. The resistor side of the LED goes to the contact with the negative mark you made earlier. Be sparing with the solder, but do make sure to get a good solid joint. It’s ok to solder the led a bit crooked onto the pads. After the solder cools, you can bend them straight up. Try to get the resistor as flat to the board as possible. Make sure the LEDs are centered over the solder pads.
To make the VFD blue on the radio, it’ll take a bit more work than on the other parts. The smoked plastic window is darker than the other parts. If you just tape the film on like we did on the overhead, you won’t be able to see it in the daylight. I learned this the hard way. To overcome this, I had to replace the window. The stock window is sonic welded into place. I removed the old one with an electric hot-knife from the inside of the radio face. This is tricky, there’s not much room to work. Smooth down the weld area on the inside of the radio face so that it’s flat. Using the old window as a template, cut a new one out of 1/16” clear polycarbonate (Lexan) sheet. Make sure it fits in the opening. Cut out a piece of the blue RoscoLux gel the size of the new window. Thoroughly clean the gel and the new window. Use clear spray adhesive designed for mounting photos to attach the gel to the window. Give it some time to dry. Attach the new window in the radio face with the gel on the inside of the radio. Affix it with a small dab of hot glue in each of the 4 corners being careful to not get any in the visible area.
After all this is done, you can reassemble your radio face. Be careful to make sure all of the LEDs line up with their proper holes in the rest of the assembly. Put in the T9 screws. Test the buttons to make sure they still work. They should have that familiar click type of feel. If they don’t feel right, they won’t work when it’s all back together. It took me two or 3 times putting it together and taking it apart before I got it right. Plug in the face to the radio main unit and test every button, and make sure all the lights work. If they don’t, now’s the time to go a few steps back and adjust.

Now that you’ve gone through all of that, you have a truck with a beautiful blue LED dashboard. Enjoy it. I hope you’ve learned a thing or two along the way, I sure know I did.


Hate Milk! Got Beer?
Jan 21, 2010
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Markle, Indiana
Your's might be different then. Mine is an 04' I think the gauges are a different style for some reason.


No, that's not a banana in my pants.
Jun 5, 2009
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Shreveport would be sweet to be all blue.. but damn its not that important for all that work hahaha.

Sissy. You scared of hard work son?


I did my entire Suburban in blue LEDs and everything but the cluster I had to solder them in. Just saying. :p

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