KOTYKB

FYI The resistors that I purchased above fixed my light warning issue

lowbee

So I contacted Fishcake321 and he is shipping me 2 resistors.....

Most load resistors being sold on the internet are 6 ohm with a maximum power (heat) rating of 50W and it is VERY WRONG for loading the parking lights with it....let me explain.....

V=IR Voltage=current X resistance so I=V/R
P=VI Power=voltage X current so I=P/V = square_root (P/R)

so the current passing through the 6 ohm load resistor is (assuming 14V car battery) I=V/R=14/6= 2.33 Amp (wow!)
Now let calculate the power being dissipate by the 6 ohm load resistor P=VI=14 X 2.33 = 32 Watt ..... Now you know why it is SO HOT....

Why would you want to pretend you have a 5W parking bulb with dissipating 32W ? I don't know...

So what is really needed.....let's see.....you want to fool the car's computer into thinking you have a 5W bulb so let's do a reverse calculation...

P=VI so I=P/V = 5/14 = 0.36 Amp. All you need is to draw 0.36 amp (in total together with the LED element) and the car's computer will think you have a 5W bulb....

Now what resistance value will let you draw only 0.36 amp ?
V=IR so R=V/I = 14/0.36 = 39 ohm

So you need a 39 ohm of overall resistance as the load resistor.....

BUT....you don't actually need to pretend you have a 5W bulb because the car's computer is probably only looking for 2.8W so doing the math again (factoring in the series resistor required for the LED, i.e. more complex math), you will need something like a 68 ohm resistor that draw only 0.2 amp of current together with the actual LED elements.

Now 0.2 amp is nothing (one-tenth of the 2.33 amp the 6 ohm is drawing) and will generate almost no heat...and yes this is proven....I will show you that later.....

So I received the 2 load resistors that Fishcake321 (my LED lights ebay vendor) sent me and I measured them to be 30 ohm. Ok so they are not as bad as the 6 ohm you get from all over the internet but still draw 2X more current and generate more heat than I like so I decided to make my own load resistors.....

Here's a pic of the 30 ohm resistor Fishcake321 sent me compare to the 68 ohm ceramic power resistor I brought from a local electronic store.....note the greater than 50% size reduction....



Here's a pic when I finished making my own load resistor with 68 ohm....note I used a CLEAR shrink tubing instead of BLACK so I can see if ever the solder joint is separated...



so now I am testing the 68 ohm resistor to make sure it gets rid of the dash ERROR



Now I am checking temperature change when I left the parking lights on for 10 minutes with a laser temperature tool....



so after 10 minutes of parking light being on, the temperature of the resistor is at about 25 degree Celsius ( 77 degree F) ....warm to touch but can't do any damage....

so I put everything back together and NO MORE ERROR on the dash....and the best of all is because the 68 ohm resistor is small enough, I just insert it into the LED light housing without worry about it being too hot and damage things around it.....

So if you have the 6 ohm resistor (goldish metal casing thing) you might want to think about changing it because it is sucking more current and generate more heat than it is really necessary.....could be dangerous too depending on where you put it....

That's all, hope this help other.....

Doug_B_928

^^^^ Great post. Thanks!

Petza914

lowbee,

That's great. Wish I had the knowledge to make these kind of electrical calculations and not just have to buy whatever is out there. Give some thought to making some of these up for sale to those of us interested in using the right size resistor that generates much less heat. I'd be in for qty 8 to use on some past and current automotive projects - no pun intended

Ehab Shoukry

Just ordered my LED DRLs from del ray customs in hopes to avoid this resistor issue and make sure I'm ordering a quality LED. I noticed that it needs an additional wire to some power source in the fuse box in order to make sure they turn on automatically. I'm curious without this wire, how do the DRL's normally turn on? I usually leave my light switch in the HOME position during the day.

Thanks.

SoCal C2S

I have the Del Rey's and they are plug and play....at least the ones they sold two years ago. I had them originally wired as DRL with a relay to switch them on (happens automatically). I later added 991 style LED head lights so I now have the DRLs wired as fog lamps.

frenchtony

thanks for the great post, I have the same problem intermittently depends on battery voltage, sorry to be a doughnut here but are the resistors in series or parallel, I'm guessing Parallel as in series would reduce the current further!