OBC Display showing false reading post instalation of new taillights

[MattSB 0]

Have just installed a couple of new aftermarket rear tailight assemblies for a 95' 320i sedan.Lights are all functioning without fault and OBC display shows " Control Check Clear" until I turn my

main park and headlamps on, it then displays" faulty tailight display".

Has any one encountered this probllem before, and how is it remedied????

Would appreciate any feed back Thanks

[Yuen 16]

Have just installed a couple of new aftermarket rear tailight assemblies for a 95' 320i sedan.Lights are all functioning without fault and OBC display shows " Control Check Clear" until I turn my

main park and headlamps on, it then displays" faulty tailight display".

Has any one encountered this probllem before, and how is it remedied????

Would appreciate any feed back Thanks

Did you mean the 'tail light failure' error? It happens with OEM tails when the replacement tails do not have as many pins as the previous tails. Usually the new ones have 7 pins when they should have 8. I would assume it's the same sort of problem for aftermarket tails, that the tail lights you got were meant for a non-OBC E36 (ie: 318).

[MattSB 0]

Hey Thanks for that

Think I can get that one sorted

Appreciate the advice

[jochen 4]

This error occurs because the Light Control Module monitors the status of all light bulbs in your car.

Even when turned off, the LCM still checks the load of the bulb (by sending a very short pulse of 12V every now and then, so short that the bulb doesn't illuminate), and notifies you when a bulb is disconnected, or open circuit (failled).

When you fit the LED taillights, the total electrical load of the taillights is reduced, as LEDs take less power.

So the LCM logs this as a fault.

What you need to do is either:

1. Fit the correct BMW electronic modul to the tail light wiring in the boot - this simulates the electrical load, and stops the error messages from appearing

or

2. Fit resistors to each light circuit - you'll need one for each light circuit that has been replaced with LEDs. Remember, taillights left and right are on different fuses and monitored separately, so you need resistors for the LH and RH taillights.

To get the resistor value measure the voltage at the taillight, the current drain of the normal taillight, then the drain of the new taillight.

Subtract one from the other to get the difference, and convert that into the resistor value using ohms law (V=IR)

ie: if you measured 12V, then 12 divided by the current = the resistor value you need.

Then multiple 12 x the current you need to get the heat dissipation of the resistor (power rating)

eg:

Imagine the LED taillight uses 400mA (check this fugure, I am not sure of the actual current) at 12V

A normal tail light bulb of 5W uses 0.4A at 12V, you have 2 of them on each side, the total load per side is thus 0.8A

If the LED only used 0.4A then your resistor would also need to use 0.4A to make a total of 0.8A (0.8 - 0.4 = 0.4)

Using V=IR, 12V = 0.4 x R, so R = 30 ohms.

You need a 30 ohm (or thereabouts) resistor.

The power rating of the resistor = 12V x 0.4A = 5watts

So if I guessed at the right power consumption of the LEDs, you'd need a 30 ohm, 5 watt resistor across the tail light circuit.

But don't use this value, please measure the current and calculate it yourself.

Cheers, Jochen

[MattSB 0]

This error occurs because the Light Control Module monitors the status of all light bulbs in your car.

Even when turned off, the LCM still checks the load of the bulb (by sending a very short pulse of 12V every now and then, so short that the bulb doesn't illuminate), and notifies you when a bulb is disconnected, or open circuit (failled).

When you fit the LED taillights, the total electrical load of the taillights is reduced, as LEDs take less power.

So the LCM logs this as a fault.

What you need to do is either:

1. Fit the correct BMW electronic modul to the tail light wiring in the boot - this simulates the electrical load, and stops the error messages from appearing

or

2. Fit resistors to each light circuit - you'll need one for each light circuit that has been replaced with LEDs. Remember, taillights left and right are on different fuses and monitored separately, so you need resistors for the LH and RH taillights.

To get the resistor value measure the voltage at the taillight, the current drain of the normal taillight, then the drain of the new taillight.

Subtract one from the other to get the difference, and convert that into the resistor value using ohms law (V=IR)

ie: if you measured 12V, then 12 divided by the current = the resistor value you need.

Then multiple 12 x the current you need to get the heat dissipation of the resistor (power rating)

eg:

Imagine the LED taillight uses 400mA (check this fugure, I am not sure of the actual current) at 12V

A normal tail light bulb of 5W uses 0.4A at 12V, you have 2 of them on each side, the total load per side is thus 0.8A

If the LED only used 0.4A then your resistor would also need to use 0.4A to make a total of 0.8A (0.8 - 0.4 = 0.4)

Using V=IR, 12V = 0.4 x R, so R = 30 ohms.

You need a 30 ohm (or thereabouts) resistor.

The power rating of the resistor = 12V x 0.4A = 5watts

So if I guessed at the right power consumption of the LEDs, you'd need a 30 ohm, 5 watt resistor across the tail light circuit.

But don't use this value, please measure the current and calculate it yourself.

Cheers, Jochen

Thanks i shall give this a go

[Docile 64]

ive been getting this error too.. but ive got stock lights on !! i was like wtf the check light on the dashboard lit up... so i pulled over and looked at the OBC.. brake curcuit falure ... see owner manual??? i had my mate check my rear lights.. reverse, brake park light.. and it all works fine.. what gives??

[kerrynzl 3]

I had the same bullshit in my OBC,[all the lights were working fine]so I replaced the brake switch, the SOB still kept showing Brake Light Error.

So I'll get straight to the point, here's how you fix it:

1: Pull your On Board Computer from the dash

2:On the Right plug there is a brown/grey wire [its 12v dc]

3:Cut the F**ker and tape it up

4: Turn off your car,then turn it back on.

NO MORE BRAKE LIGHT ERRORS

Hope this helps [Hey I don't need acomputer to tell me the brake lights dont work, 'the cops do that for me']

[Yuen 16]

ive been getting this error too.. but ive got stock lights on !! i was like wtf the check light on the dashboard lit up... so i pulled over and looked at the OBC.. brake curcuit falure ... see owner manual??? i had my mate check my rear lights.. reverse, brake park light.. and it all works fine.. what gives??

I had that happen before but it was due to contacts. The contact was not too good between the bulb holder and the light housing (the metal circle ring bit) so when the car moved around it sometimes made it lose contact. You can use some ghetto fixes to fix that, what I did was stuff a little piece of cardboard behind the metal ring on the light to make it push forwards a bit.

Also, I've heard that some bulbs that are on their way out will cause this error. If you have a new bulb you can experiment. Something to do with the filament and how the computer uses resistance to determine if the bulb is 'there or not'.

[Docile 64]

piece of crap smart as computer car... what happened to the good ole days.. where cops do that job for you??

[conrod 1]

Have just installed a couple of new aftermarket rear tailight assemblies for a 95' 320i sedan.Lights are all functioning without fault and OBC display shows " Control Check Clear" until I turn my

main park and headlamps on, it then displays" faulty tailight display".

Has any one encountered this probllem before, and how is it remedied????

Would appreciate any feed back Thanks

The German check module is pretty clever, it is trying to tell you "get rid of those crap aftermarket lights you have fitted and fit the "Originale BMW Teille" back in!!!!!"

Except there is no warning light for that, so it picked faulty tail light display, as that is close enough!

Edited September 3, 2006 by conrod

[Yuen 16]

^ German engineers!

[WarNox 1]

haha its not a crappy computer. there is a switch above your break pedal. got no idea how much it costs, but they tend to go faulty, swap that and u'll get no more errors. ill try and find a link for the diy, its not very expensive.

if u buy aftermarket lights ask if they work with the obc. i know some on trademe do as i asked.

found it:

http://www.pelicanparts.com/BMW/techarticl...rake_Switch.htm

Edited September 8, 2006 by WarNox

[kerrynzl 3]

Yeah I mentioned the Brake Switch before! I've been there myself