2001 S80 2.9L "Check Brake Light" after replaced with LED

[thienle]

Hello,

I replaced the brake lights with a LED. All the lights are working fine but the "Check Brake Light" still indicates everytime the brake paddle was pressed. I found out from the internet that LED draw less current so the computer is thinking that the bulb is bad. One remedy is to put a resistor in line (in series) with the LED bulb to increase the resistant equal to the traditional incandescent light bulb.

Any advise of how to tricks the computer to get rid the "Check Brake Light" beside put a resistor in series with the LED light bulb? Thanks you very much.

[Oly_850]

It is electrically possible.

Saw these: http://m.ebay.com/itm?itemId=130715239352

Here:

http://forums.swedespeed.com/showthread ... ail-lights

[mikealder]

You need to put the correct value resistor in PARALLEL with the LED for this to work, you will need to do it to both LEDs.
To work out the correct value is easy, we simply start with basic ohms law and a few facts:

Assume cars voltage is 13,8V
Assume old brake bulb was 21W rated

With the above the 21W bulb will pull 1,522 Amps your LED will be drawing around one tenth of that value which is why the car thinks the bulbs are blown, you need to add a resistor that pulls the remainder of the current which is about 1,370 Amps

13,8 / 1,370 = 10 Ohms

Next to ensure the resistors don't burn out we calculate the power rating for the resistor:

W = I x V

1,379 x 13,8 = 19W

Resistors are supplied in various preferred values, you should go for a 10 Ohm rated at 25W - Mike

[jimmy57]

Put the conventional bulb back in one side and then go back 50 or more feet behind car and have someone apply the brakes. You may decide that you want the conventional bulb due to visibility.