MattSB

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

Hey Thanks for that

Think I can get that one sorted

Appreciate the advice

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

Not a big e36 person -

But as far as I know.

2 and 4 door tail lights are different.

Facelift and prefacelift tail lights are different (pre 96)

Welcome to the site - hope you're enjoying your new car.

Thanks for this, will stay clear of 2nd hand at the mo'

until I'm a bit more familiar with makes and models etc

Great site to have

Thanks for the welcome, am really enjoying my new Bimmer

The main difference is 4dr and 2 dr.

I have standard tail lights from a 92 4 door 318 sedan (lenses only). If you need them let me know and I'll chuck them on trademe.

Thanks for your reply, am looking for the whole unit as the fittinngs are worn, appreciate your response tho'

Hi Folks, am putting out a call for help re my new BMW, have a 95' 320i sedan the only thing dodgy with it is that it has worn tail light bulb connectors & housing is worn also. Am looking at a In/net purchase of 2nd hand tail light assemblies from a 91 325i, just wanted some helpful knowledge from some one in the know if these two cars have compatable tail light assemblies.?????

P.s have waited a long time for this car and am totally besmirched !!!!!

Am a new BMW owner of a 95' 320i E36, rear tail light assembly bulb connectors and fittings are worn, am looking at some 2nd hand 325i E36 rear tail light assemblies, are these compatable with the 320i ??