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Rx400H Radio/climate Control Led Project *pics*

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Hey guys,

Just wanted to update on another one of my recent projects. This one involves replacement of the bulbs/LED’s in the radio and climate control units in the Rx400h.

If you have an 04-09 Rx330/350/400h with NAV, you may notice that the lettering for the climate control unit doesn’t light up the same shade as the lettering on the radio. If you look closely, you’ll notice the lettering on the climate control unit is more of an “aqua” color while the lettering for the radio is more of a milky white color. Compare both of these colors to the speedometer gauges, and you’ll notice neither the climate control unit lights nor the radio lights are pure white. It doesn’t show up well in pictures, but in person it’s VERY noticeable. Here’s a pic to give you an idea of the color differences.


This has always bothered me since the day I got it. I never understood why the colors didn’t match, but I knew I had to fix it.

So I bought a used radio ($50 on eBay) and took it apart. I found that the buttons are illuminated by miniature BLUE SMD’s (different type of LED’s) with a yellow-ish rubber cap over them (which must be made with some type of phosphor material) which produces a yellow-ish white color when ON. Why the engineers did this completely baffles me, but I guess we’ll never know… :blink:

Then I decided to take apart the NAV/climate control unit from my Rx. Upon opening the unit, I discovered that its buttons are illuminated not by LED’s or SMD’s, but by BULBS! Yes my friend, in 2008 (or 2005 when it was designed) Lexus still uses bulbs in its console pieces. They’re just regular halogen bulbs with blue caps- which when ON, produce that ugly “aqua” light.

So I decided to convert both the radio and climate control units to white SMD’s, so they’d both match, and match the gauges. I didn’t take any pictures along the way, so I’ll try to describe my methods as best I can. It gets a little boring, so if you want to just move on to the pictures, skip this part! :wacko:

Converting the radio LED’s was easy. I just marked each SMD to determine which solder ends were (+) and (-) and removed them with pliers. I did however leave the blue SMD’s around the radio dials, as I wanted to make them blue to match some of the other blue accents I’ve added in my Rx. I just removed the yellow phosphor caps and kept them the way they were.

And then came the problem of locating which white SMD’s I’d be using. I decided to use some from an old Rx330 cluster I had laying around, as I knew they’d be reliable and match the Rx400h gauges PERFECTLY. So that’s what I did- I gently removed several white SMD’s from the old cluster and soldered them onto the radio circuitry. And presto, the radio was complete!

Then came the job of converting the climate control unit. I gathered more white SMD’s and removed the bubs from the unit. I then soldered the SMD’s into place and used proper resistors to ensure they won’t burn out.

But this is where I ran into MAJOR trouble. After the job was completed (and looked right) I took a little joyride around my neighborhood, and later picked up my girlfriend so she could see what I had done. But once she got into the passengers seat, the yellow airbag lights on the climate control unit (both AIRBAG ON and AIRBAG OFF) were illuminated, as well as the red icon in the gauges. Usually, only the AIRBAG ON light would illuminate… So I knew I had a problem. :(

The following day, I looked the issue up in the manual. It read that if both the yellow lights were ON along with the red icon in the gauges, that there was a “malfunction” and to see the Lexus dealer. So, that’s exactly what I did. When I got to the dealer, they thought the issue was just as simple as needing to reset it, but the problem wouldn’t go away. They were able to diagnose the problem as a break in the airbag circuit “somewhere” in the climate control unit. I was VERY surprised (as well as not-surprised since I had just tampered with it) that their computers were able to tell them that. They also told me that I’d need to pay $225 for the time it took for their tech to find the problem! Since I had tampered with it, they couldn’t cover it under warranty… They also said that I needed a new nav/climate control unit!! :blink:

So, a few hours and $225 later I was back home trying to figure out what went wrong. I opened everything back up, but couldn’t find a SINGLE thing wrong- no missing diodes, no loose plugs, NOTHING that would indicate a break in the airbag circuit. After spending at least a day looking for the problem, I came to the realization that the unit was SHOT. I decided to remove the white SMD’s and put the bulbs back in, thinking I would sell it on eBay and have to buy another unit.

BUT, after I replaced the bulbs, I put it back in the car “just for kicks” to see if it did anything. And what do you know!? IT WORKED! The airbag light issue was GONE and there weren’t any error codes. I immediately removed the unit and opened it back up, and studied the wiring. I traced EVERY wire from the plug that feeds the airbag module in the climate control unit, and discovered that one particular wire loops around to every bulb- meaning, that it uses the filament in each bulb to spread continuity to the airbag module! Therefore, when I removed the bulbs, I broke the continuity to the airbag module, and THAT’S why it wasn’t working. Unlike bulbs, which use a metal filament, only a limited amount of current can pass from one side of an LED to the other. <_<

So to fix the problem while still using the white SMD’s, I simply kept the bulbs and just wired the SMD’s over the bulbs, so both the bulbs AND the SMD’s would illuminate. This way, current could still pass through the filaments to the airbag module, and the white SMD’s would still work. I simply painted (using black acrylic) the bulb caps to prevent any of the aqua light from passing through.

Several hours later, it was finally complete (again…). The only step remaining was modification of the VFD clock to the correct color.


Unlike LCD’s, VFD’s (vacuum fluorescent displays) produce their own light via phosphor coated integers which produce a very BRIGHT aqua light. THIS is why I thought the engineers used bulbs with blue covers for the climate control unit, thinking they were limited by the color of the VFD. But with some research, I discovered that it IS possible to change the color of VFD’s by using different tinted covers. From the factory, the 04-09 Rx VFD clock has a reddish cover, but the color is still quite aqua. I found a site online that sells various shades of VFD covers, and I bought a few.


I removed the factory VFD tinted cover from the Rx’s clock on the climate control unit and cut out a piece of the websites RED202 (Red 20x2 VFD Filter) which worked PERFECTLY. Just a shade different from the factory one, it makes the lettering of the clock PERFECTLY white, which matches the new white SMD’s I added in the rest of the console. I glued it into place, and I was done. You may also notice that the factory clock tinted cover is very “blurry” (not even on the outside to reduce glare), but the new film is crystal clear. It’s MUCH easier to read now in both night and day. In the pics below, note the difference in color from the clock and the compass on the rear-view mirror- they used to look the same, but now the clock is much more white.

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Well, enough with the words, here are some pictures of the final product!! It may seem by this description that this was a hard modification, but in reality it was VERY easy. If I knew then, what I (and you all) know now, it wouldn’t have taken more than a few hours. And don’t be afraid to try this after the issue I had with the airbag lights… as long as you don’t completely remove the bulbs in the climate control unit, you won’t have the problem.

So enjoy and please comment! :)








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Great work, as always! I have noticed the different shade of the radio and nav controls, but figured they were made by different companies with slightly different LEDs, not expecting filament bulbs! Just about every part of the dash illumination doesn't match on this car. It's like they couldn't decide on a color scheme.

Cupholder lights: blue

Door handles/overhead illumination/glovebox: amber

Doorsills: amber (2007), blue (2008)

Steering wheel/shifter: green

Gauges: pure white

Radio/nav: various shades of green/blue/white

Now you just need to change the ugly yellow-green seat heater controls and gear selector illumination. Did you change the radio knobs to blue as part of this project?

For the gear shift indicator illumination, it would look good to have a separate LED for each position - white for P, D, and B, red for R, and green for N. Then it would match the LEDs on the gauge cluster.

Another project would be to install brighter LEDs in the steering wheel buttons and window controls. I've always thought they were too dim.

Very interesting about the bulbs carrying continuity to the seat airbag circuit. So you would have the same problem if any one of the small bulbs burned out? Bad design in my opinion. Maybe you could install a jumper wire to bypass all the bulbs and go directly to the airbag sensor.

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Why in heavens name did they use the bulbs for the continuity to the airbags...that is mystifying, however you have excellent troubleshooting skills...and as always a excellent writeup...

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Thanks guys! And i agree, Lexus engineers were definitely taking the cheap way out when designing these pieces. I too thought the light differences between the radio and climate control unit might be due to different manufactures, but based on the internals (besides the lights) they both look the same. And it makes absolutely NO sense why they designed it so that if a bulb burned out (breaking the filament and opening the circuit) the AIRBAG system wouldn't work- especially since the AIRBAG is a very important system. I have NO idea what Lexus is gonna do years down the road when the bulbs start burning out and everyone starts coming in with airbag problems. The bulbs are not easy to get to, and they're soldered onto the circuit board, so it's not like they could replace them. Very poor engineering in my opinion.

And for the moment i'm gonna leave the green lights in the heated seat and shifter panels as well as the window and steering wheel controls. I kind of like the look... I'm thinking it might be "too much" white if i changed those out too? But it wouldn't be that hard to switch them to LED's if i decide to do so in the future...

As for the other lights in the Rx, i haven't the slightest clue why they used such an array of colors (i too agree it doesn't look good). The foot well lights and upper console lights (illuminating the shifter area) used to be yellow but i've switched them all to blue. The only yellow remaining in mine is in the interior door pockets, but it's VERY difficult to get to them so i've been putting off that project...

And yeah i did make the radio knobs backlight in blue, i think the blue rings match well with the blue rings i added in the gauge cluster. I'm trying to keep up with the "hybrid" blue theme. <_<

Can you guys think of anything else i should do? :whistles:

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The door handle lights aren't too hard to get to (just remove the door panel and it's on the back). They are encased in milky white plastic diffuser. I actually tried adding more yellow LEDs on one of them (while I had the door panel off to add LED mirror turn signals), but found that such a low current is provided to these LEDs that adding a single extra LED made all the other ones dim to where you can barely see them at all! The ECU that controls these doesn't provide enough power to add any more.

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The door handle lights aren't too hard to get to (just remove the door panel and it's on the back). They are encased in milky white plastic diffuser. I actually tried adding more yellow LEDs on one of them (while I had the door panel off to add LED mirror turn signals), but found that such a low current is provided to these LEDs that adding a single extra LED made all the other ones dim to where you can barely see them at all! The ECU that controls these doesn't provide enough power to add any more.

Oh wonderful... I wonder if it's enough current to run a blue LED in its place? Most Blue and White LED's that i know of require more energy than the reds and yellows. :unsure:

I guess if that didn't work, i could wire a blue LED taking current from the window switch lights (since they're always on at night). I know those are bulbs which are probably 12V. <_<

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