Introduction: Diy Cheap Asian Style Car Underbody Lights

Picture of Diy Cheap Asian Style Car Underbody Lights
hey, im finally making my first instructable. i have tons of instructable-worthy projects and diys but never had the time to accomplish one. so during this school holiday i present to you my very first one- which is LED underbody light for ur car.

i made it such that the lights activates when you unlock your car with the remote or key. and slowly fades down when you lock the car after closing the door.

the project is very simple. but lots and lots of time is invloved if you want a good result.

the car i used for this project was a Honda Civic, which is my bothers.

the idea of this project is to produce underbody lights while keeping the price to minimum.
retail shops sell 24led sticks for 40$ (something stupid like that). i am using 108 leds i got for about 10-15$

before u actually start this. please read through the instructable carefully. see if you are confident with your abilites because I take no responsiblity for you if u blow fuses, screw the car up, etc, so do this at ur own risk. also im not responsible if u get pulled over by the cops if u do stupid things with these lights. eg turning it on constantly when driving. so once again. i take no responsiblity whatsoever. i provide the information, ideas and instructions while its up to u if u want to follow laws, instructions etc.

i dont know if anyone has already made instructables on this. but this project's idea is 105% original from me. i have not copied from different sources or whatever. if you have a similar project, it is a coincident. i am happy to link ur instructable as a "see also" or something similar if u want to.

Step 1: Collection of Materials and Parts

what i used:
a switch(4 state switch. 3 state + 2 state switch is ok too)
packaging foam (styrofoam??)
hot glue + gun
thin and long piece of wood
lots and lots of led, colour is ur choice.
solder iron
lots of time (4+hrs)
mineral turp and a random piece of cloth.
lots of capacitors, larger capacitance the better. must 16v or larger. i got about 19800uF.
masking tape and/or eletrical tape.
wire strippers and/or wire cutter.

the leds can be supplied from a local electronic shop or online- ofcourse, with price variation depending where u shop. i used red, which is the cheapest and best suited colour led for my purpose.

Step 2: Constructing Your Led Sticks

Picture of Constructing Your Led Sticks

i used wood here for the base to hold the leds up, since i have tons of long and thin piece of jarrah after the renovation of my house. use pvc or whatever if its more applicable.

the configuration i set the leds up are in series and parallel.

NOTE that red leds are driven by ~2volts dc. while blue, white, even some green LEDS require ~3.3 volts dc.

with 12.6-14.6v supplied from the car, u can connect 6 leds through series. 2*6 is 12v, so a resistor is required to prevent the leds blowing up. u will find a 30ohm nicely fits into the equation. however, im going for 27ohms, making the leds gong about 2.1v when supplied 14.6v

using a packaging foam, i have created my own special apparatus to solder the leds equally distance and spaced apart. i have chosen to space the leds 5cm for the side lights and 4cm for the front and back lights. pretty sure theres better ways of doing this. but didnt think that much. remember to dig a little hole so the solder iron or led legs wont touch the foam.

this process is probably the longest for the whole project. took me few hours including distractions, breaks, etc.

Step 3: Wiring for Led Strands.

Picture of Wiring for Led Strands.

continuing from the last step, we now stick the leds to the wood. i used hot glue. which is really handy since it hardens quickly. i used hot glue to stop the leds moving and then painted the thing with PVA glue (dont apply too much PVA, its runny and will stick the leds to the wood, u want the leds movable/adjustable, so give it about 5-10mm of spacing.

the wiring is pretty simple, if u are knowlageable in eletronics. this will be simple as. but for the beginners, i have included a pic demostrating the wiriing.

leave about 10-15cm of wire hanging out of the wood(only one end of each side). this will make easier installation for future steps.

Step 4: Capactiors

Picture of Capactiors

while letting the pva glue aside to dry. time to make ur lights fade-able.

ive already had this made before. so only got a picture of the capacitors.

-ve marked on the picture is where there is a black band going from the top to the bottom of the capactor with the "-" symbol.

connect however many u want in parallel with eachother. make sure it does not short then encase or insulate the capactior bundle as shown in pic2

Step 5: Testing

Picture of Testing

now its time to test what u've made so far. connect the led strips to any 12-14v source. then stick the capactior in parallel with the led strips. all the leds should light up when connected and slowly fade out when you disconnect from the source (leaving the capactiors conencted with the leds).

if it does not work. check polarity of the led. and check supply voltage to see if its enough.

note that if u apply too much voltage. the leds might blow and u have to repair the led strip.

Step 6: Installing the Lights to Car.

Picture of Installing the Lights to Car.

now its time for you to use ur imagination. every car is different and your personal taste is different to mines. install the leds wherever u feel like.

i used hot glue to stick the wood to the car chasis. this is to prevent the sticks from falling down.
i then applied stronger (heat resistant) glue to hold it up.

if u have access to a car jack, then use it. or even better, a car hoist. i recommend screwing instead of glue. but i didnt want to drill holes.

one thing to watch out for is the exhast pipe. it gets hot and might melt ur wires it its too close.


after reading the comment from Instructables4ever, ive realised that using neodymium would make installation so much easier. and removable if you wish to remove them.

take apart a hard drive and steal the magnets. chuck some super strong glue on the back of the led stick. and let it dry/cure.

you should be able to just stick it on the car and it wil stay there untill you force it out.

should of thought about magnets earlier. would of saved so much time.

thanks to Instructables4ever. i'll use magnets if i were to do this project again.

Step 7: Wiring

now its time to wrre it up. similar to the previous step, u can do this however u want. but to allow remote activation. i piggybacked the led to the wires going to the car roof light.

make sure the fuse or wiriing can support this extra load. if a fuse blow, then find a different wire and use power transistors or a relay to syncronise the fading with the roof lights.

to wire the lights, +ve goes to +ve and -ve goes to -ve. simple as that. but finding the wires that connects to the roof lights might take some time. helpful hint- turn ur car to "II", "ON" (just before ignition) keep the fans going to cool down. summer is pretty hot.

Step 8: _ STEP 7.5

Picture of _    STEP 7.5

this is optional. for people who want more options with the lights

it is quite difficult to illustrate step by step how to wrire each wire due to the vast difference between car models and makes. but if u made it to this step, im pretty sure that you are capable to wire it without mistakes. at times like this, a multimetre is ur friend.

but what this is is a switch.this controls the lights.
the modes are:

-ON- constantly
-ON- when unlock door with remotes and OFF when lock door
-OFF- when unlocked and ON when breaks are applied, no matter if car is running or not.
-OFF- open circuit, no lights at all (incase gets pulled over by cops or if dont want it on)

an off swich is a good idea if u dont want ur A$$ mugged when u drive (or park) in dodgy areas of town.

this will be easy if u have a proper 4 state switch. i dont have that at the moment. so i used 3 seperate switches. i bridged the switches so that it only functions one function at a time.

the reason why i used a relay was for 2 reasons. if too much load is on the break light wire. it will dim the break lights. 2nd reason is the click the relay makes when swiching. this is useful so u know that its switched in the "break light " mode. obviously, u wont drive everyday with the "breaklights mode" on and the noise isnt that loud either. so its a pretty good idea.

i used expoy to stick the switches to make all of this 1 unit. make sure not to get any in the swiches. or else u have a switch that is stuck.

for my particuar car, the 12v stays live on the roof light wire and the gnd is the swich, which totally screwed up my "constant light" function. i added a relay to short the "gnd" to a real "GND". this makes it constant on. even with the keys out and doors locked.

after u are finished, check if it works. if smoke comes out, ur stuffed. if u hear a pop, most likely a fuse blew, check ur wiring. if it lights up, congrats, u finished the tough step.

Step 9: Hide Wires

Picture of Hide Wires

now is the important step. make it a professional finish, for both outside and in. cut wires shorter or shove it behind some panels. whatever. put the switch somewhere, probably best to secure it so it wont move either.

Step 10: Wait Till the Sun Drops.

Picture of Wait Till the Sun Drops.
probably the most annoying step. waiting for the sun to set. see the light. now, the lights will be all out of place shown in the first picture. but remember i told u to leave the leds adjustable? well this is the time we need to adjust the leds.

heres a video on the break lights mode. was mid-day when making the video. but u'll still see it in action.

Step 11: Go Driving at Night.

Picture of Go Driving at Night.

have fun with your new lights. hope you felt the time was worth it.

if you have a high pay job, use that 4+ hours to buy the lights and get some guy to install for u. but DIY gives u pride. and DIY rocks. since u make somethign that no one else has. so its unique.

an extra function for the led is to make it beat with the music or bass. its my brothers car, no subwoofer, so no point in making it sync with bass. however i intend to add that feature when i drive my own car again(when its out of our repair shop).

dont know if i will produce anymore instructables. but i have many useful DIY projects.

some projects you might be interested that i have made/thought of:

using spare cd decks, few atx powersupplies and high quality amps and speakers and a SLA battery, i made a sound system that i felt was better than my logitech z5500. so i returned the z5500 and got my $550 back and a better system. all the parts were spare and cost 0$. u can actually spot the cd deck in a few pictures in this instructable.

lights- blue (16 LEDS) light for the car roof. and green light (240LEDS!!!) for under seat.

lights - put strands of white led, similar configuration to the leds in this instructable at the back of the car trunk/boot. this is better than the haolgen light and brighter. ive also spreaded out the leds so the light is uniform across the whole boot space.

DIY projector- i got this idea from some instructables from this site so credits goes to those authors.

remote controlled lights. using a relay to control ur room lights with an infrared remote.

remote controolled windows. i am thinking of making my windows controlled (open and close blinds) by switch or IR. powers
using solar. since window = light shining = free energy. i have a few panels hanging arround so its gonna be a cheap project.

bass/music activated lights. using a cheapo amplifier do a full rectification of the speaker output and then drive the leds with the light. hook it up to the subwoofer out if u want bass lights .

thats all i can think of now. note they are ideas only and no instructables with them. but im pretty sure these ideas were already thought of and made. few googles or searching could give u answers.


sidnov made it! (author)2015-08-29

I made this on my ford Figo.....thanks for your base idea, even though I took a slightly different route :-))

nityashish (author)2014-03-10

hello slimguy379, please can you give me schematic diagram of whole wiring and relay work. please please please man i want whole schematic diagram.

slimguy379 (author)2009-05-30

if you sanded the leds, would the light disperse better rather than beam? also im curious if any issues with holding the strips to the body, has occurred? the answers would be very much appreciated

MackeFeet (author)slimguy3792012-06-18

Yeah sanding works.. I made a LED bar recently and sanding the tops of the LEDs works great and makes a very nice glow effect. Great for under a car.. Just be sure to use 400+ grit sand paper!!!

robikazz (author)2011-05-09

And so much easier of stealing if with magnets... I will make mines with screw, and then put hot glues on screws, so that even I could not take it off so easily ;]
And for later I will hope, that everything will be okay and LED's wont fry out for long :D

usLEDsupply (author)2010-12-11

I like the lights under the seats:-) i have done some under the dash and they were sweet but under the seats would have been a nice addition

zack247 (author)2010-08-10


electrobrandino (author)2010-07-30

Thats one hell of a rice cooker....rofl... Nice job tho :)

howry (author)2010-01-06 were tlaking about the switches at this step, is there a way to have a switch that way that when the doors are open the lights are on,  and add to that you have on and off as well when the doors are closed? would you say that its 3 way or 2 way? cuz ive found a really nice switch that will look good inside.  

neilo510 (author)howry2010-01-28

you could accomplish that via relay. Run your hot power constant to the relay, signal wires from your door switch and also from your on/off switch to the energizing side of the relay and when one or the other is switched on or (door open) it will close the circuit and turn the lights on when wired to the energized side.

neilo510 (author)2009-05-06

In ohio, as long as you can't directly see the bulbs or leds its fine for any color. This is a pretty cool instructable, but if you get on ebay and do some quick searching you can buy a kit like the one i got, with all colors imaginable for around $100 ready to install and as i said, you get all colors / flash patterns in one package.

kyles89 (author)neilo5102010-01-28

do you know the brand of the kit? cause that sounds easier to do.

Racer13 (author)2009-11-18

where did u buy the LEDs?

gwolff (author)2009-09-30

how do you make strips with more than 6 leds? 2v led * 6 is your 12v battery.. Are you just wiring each set of six in parallel with the other set of six?

Pie_eata (author)2009-08-20

I would use flatheaded leds instead of normal ones, they give off a 180 degree radius instead of a focused beam would take care of the circles ;D

zerox61 (author)Pie_eata2009-08-21

yeh i agree with that. however i fixed the problem by using a pair of sharp wirecutters. snipped the round bits off. now its perfect. ill post a photo when the sun sets.

zerozz (author)2009-08-13

What size capacitors? The ones shown are 10 volt instead of 16 volt. You mention you have 19800uF but is this the total of all the capacitors or the value of just one capacitor? Can I use just one large capacitor or is there a need in connecting several together in parallel?

zerox61 (author)zerozz2009-08-14

actually, the 10v ones shown in the pictures was just for demostration purposes. i used 16v. it wont matter what size capacitors you use. you can use a big one instead of lots of small ones. and its the total value which is 19800uf.

capricorn111 (author)2009-08-03

i like this project. but dude i have a bit problem regard resistors . it will be great if u can send me circuit diagram of this project. my email id

capricorn111 (author)2009-07-28

THIS project is awesome dude..

alexharned (author)2009-07-24

So does the +ve for the capacitors pigtail go between the battery and the Leda and the negative to the negative on the battery? How does this hook up?

mmcpherson4 (author)2009-06-01

i want to do that to my car, but its illegal to have them on while driving where i live... ( BUT, i can have when im parked! TEEHEE)

OverSaltedFry (author)2009-05-18

I think their illegal because it distracts other drivers, but then again corvettes are legal and they completely distract me

tamakid (author)OverSaltedFry2009-05-23

yea in australia they are illegal, cuz they distract other drivers

Dr_Stupid (author)2009-01-15

Also, check your local laws, these lights are illegal in some states.

ste5442 (author)Dr_Stupid2009-02-02

They should be illegal in all states :-)

PCBPolice Electronics Forum

Dr_Stupid (author)ste54422009-05-06


Derin (author)2009-04-23

Hey,I have that same striped electrical tape!

bug on fire (author)2009-04-05

hey dose anybody know about the law of these things in new zealand What about the inside

Sigsaucer647 (author)2009-03-01

so these things are illegal to drive with?

JB4times4 (author)Sigsaucer6472009-03-10

In the US I know they are, I'm not sure about other places.

JB4times4 (author)2009-03-10

So did you have to run 1 wire to every 6 LEDs? or did you just run 1 wire to each strip? I'm just confused on the actual wiring of these. is it 1 wire for the entire thing? is it 1 ground per 6leds? and do the grounds connect, or run all the way back?

krowii (author)2009-02-26

omg why is this ASIAN style? I'm so offended. :p

huang.wencong (author)2009-01-13

In Indonesia (to be precise in Batam), you can get a neon light at a cheaper price because LED's here are sooo expensive. They cost you around Rp.700,- per pcs. And here it's not illegal to use blue lights. Even in here some motorcycles are modified to sound like police sirens and the police is just sitting down with his radio and saying ha ha ha! But nice instructables, will try to install on my motorcycle. :)

mdgnys (author)huang.wencong2009-02-16

Most neon lights are realitively cheap but the expensive part it the transformer!


groovezilla (author)2009-02-11

pretty cool. next time, take a fine grit sandpaper and lightly sand the tops of the leds. it diffuses the light and looks really smooth.

dnguyen415 (author)2009-01-30

Did you do your interior lights yourself?

zerox61 (author)dnguyen4152009-01-31


krieger (author)2009-01-24

Great Project, my son has a 74 bug that will be getting a set of lights . and I have a Jeep in need of interior lighting, thanks

a_d777 (author)2009-01-22

In my city, Faridabad, there is no proper drainage system... in monsoon season, almost all the road are over 12 inches under water!!!

a_d777 (author)2009-01-22

lol here in India, cops dont care.... nothing is banned! other than drinkin n drivin and smokin and drivin as well! i know i know...Its really sick! and smokin up is illegal too!!! India is a country which produces a large amount of weed...and that too good quality! but still its banned lol! nice mod !! 5*

junits15 (author)2009-01-12

pretty cool, i hope you live somewhere that there is no snow! the snow and salt would cake the leds making them impossible to see and eventualy the leads would rust away, it would be cooler if the led rods were in a tube, to protect them, nice idea though, rating:*****

zerox61 (author)junits152009-01-12

australia has no snow but lots of rain sometimes.

cornflaker (author)zerox612009-01-16

Hey these are illegal in Australia aren't they? Or is it just while your car is moving or something?

yes they are just as long as you dont have red or blue (emergency vehicles) there may be a few more colors but i dont know, make sure you check first.

awang8 (author)godfreyandthandi2009-01-20

In Australia the only legal colour is blue. If you have red AND blue then you're going to be busted big time.

cornflaker (author)awang82009-01-21

Haha hell yeah, thats cool that we can have blue though cause thats like one of the best colours.

mbainrot (author)awang82009-01-21

From my understanding, I don't believe there are restrictions on the colours. BUT the catch is the lights can not be on when the vehicle is in motion, as it may "confuse" drivers (Maybe drivers with pidgin brains)

junits15 (author)zerox612009-01-13

ok, because i live in new england si I get lots of rain and snow, which would kill this set up, :D

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