Help Please ---- with LED rear light

[Bear]

Yeah warships make aircraft looms look like playtime at the boffins tea party.

Or try a Multibus card cage with 6 cpus running in it. There is far too much technology in modern vehicles. It's fine when the vehicle is new and warrantied but 10 years later, when the mechanicals are still good any electronic fault costs more than the car or motorcycle is worth to fix. I was, over ten years ago, quoted £37.50 + vat per hour to hopefully (the franchised dealer wouldn't guarantee success) diagnose an ABS warning light on a Rover 820. It turned out to be both brake lights failed.

To return to the original thread, however. The only way I know to determine if a bulb has failed is to drive it with a relatively small current so if the filament is intact the voltage developed across it is small, whereas if it's failed, the full supply voltage will be measured. If the ECU takes advantage of the thermal properties of bulb filaments then a very low value resistor is required. If, on the other hand, it tries a small current (say under 50mA) then perhaps 100 ohms would be a good starting point. Now that I'm retired I unfortunately no longer have access to the test equipment required to answer the question.

 

[gjclark38]

I Have exactly the same problem

When you get the solution can I be cheeky and ask you to post it here or pm me

thanks in advance

Grahame

 

[SMB]

To return to the original thread, however. The only way I know to determine if a bulb has failed is to drive it with a relatively small current so if the filament is intact the voltage developed across it is small, whereas if it's failed, the full supply voltage will be measured. If the ECU takes advantage of the thermal properties of bulb filaments then a very low value resistor is required. If, on the other hand, it tries a small current (say under 50mA) then perhaps 100 ohms would be a good starting point. Now that I'm retired I unfortunately no longer have access to the test equipment required to answer the question.

I had an F800ST. It had the Canbus system and no fuse box. I was getting the Lamp Failure light coming on even though the bulb was working; it appeared to be working as bright as normal. (I know that if the rear light fails the ECU will partially illuminate the brake light to give a rear light).
I resolved the problem by cleaning the contacts. All was well. Surly this indicates that the ECU monitors the current through the filament and does not do just a continuity test.
Hence the resistors need to fool the ECU must make the circuit draw the current that would be expected from an ordinary incandescent bulb.
SMB

 

[Pukmeister]

............the ECU monitors the current through the filament and does not do just a continuity test.

Hence the resistors need to fool the ECU must make the circuit draw the current that would be expected from an ordinary incandescent bulb.
SMB

Yup.

 

[Bear]

Given the ability to use a dim brake light as a substitute tail light, the implication is that the ZFE module that drives the bulbs can vary the voltage sent to them, either by applying a low steady voltage or, more likely I would have thought, by switching between full voltage and nothing at a fairly high frequency. If the lamp check on startup is looking for the low resistance of a cold filament then corrosion on the contacts could well cause a LAMPR error despite the bulb lighting up when full voltage is applied.

 

[Ali-bear]

An electrical engineer writes:

There is no point trying to measure the resistance of the new LED lights, you will only get confused and the figure will be pretty much meaningless because it is so much higher than the conventional bulbs.

What you have to do is add a load resistor in parallel with the LED unit (ok one each for the tail light and brake light) that takes sufficient current to convince the ZFE module that there is a normal bulb there and that it is working normally.

To do this you have to realise that there will be a threshold current that the ZFE uses to tell if the bulb is OK or not. This will be somewhere between the regular current used by the bulb and zero.

Tail light: takes about 5/12 = 0.4 Amp
Brake light: takes about 21/12 = 1.75 Amp

So I guess you need to waste about 0.2 Amp and 1 Amp respectively.

To do this from a 12V supply gives a resistance of

12/0.2 = 60 Ohms
12/1 = 12 Ohms

And this will dissipate

12*0.2 = 2.4 Watts
12*1 = 12 Watts

So you need resistors beefy enough to waste this much heat. Obviously if the ZFE threshold is set lower than my guess, you need to waste less current so can use higher resistance values and dissipate less heat in them.

But if you are doing this I'd check out what resistors you can get hold of. Something like a pack of five, 47 Ohms, 3 Watts would just about do it (using four in parallel for the brake light, and one for the tail light).

 

[Rong]

Why not just wire in a light bulb, in parallel, and black it out? Works a treat. Or you could be clever and have it illuminate the underside of the bike just like a street rod (yuk)?

 

[Ali-bear]

You could get one of those "cross of iron" shaped tail light units

Or how about a nice tasteful skull with eyes that light up when you brake?

 

[gzpainter]

but all this talk is for 11gs and not for 12gs...(the former one has fuses where the latter one has CANBUS...if I am not wrong... )otherwise where is the fusebox to change the fuse for the brake light and relax from the problem???

For us that we have a GS/GSA , it is mandatory to go to the dealer?
I am asking because I bought a clear tail/brake lense for my GSA and I burned the red bulb. I bought a led 1157 bulb (this one...http://www.aceparts.com/led-bulbs-b...ase-dual-contact-bay15d-380-1157-r10w-r5w.htm)
to solve and improve my lights at the back and now I have again this irritating message "LAMPR" ...

anyone that can help us???

 

[littleredrooster]

but all this talk is for 11gs and not for 12gs...

No, I think you'll find that we're talking about 1200s here, not agricultural old 11xx's

 

[gzpainter]

yea...then where is the fuse box for the brake and tail light ....as I check all the manual and the only fusebox that it is mentioned is at the front right and is for the auxiliary lights.....

Basically what I have understand till now and correct me if I am wrong ...we have by some way to increase the resistance from the tail/brake light so the ECU don't read lower voltage and show error message...right??
Beside creating DIY thing with resistors from maplin..(which I am working on it..) is any other way to use our led tail/brake without cutting or welding on factory cables??
I noticed that DaveyP bought a separate loom connection to connect his led tail light..is that a solution? how can be sure that using that loom we will have solved our problem??

PS: I got obsessed with my led bulb....and I am planning to use it....

 

[Ali-bear]

Apart from just the fiddle factor its not really worth fitting LED bulbs for the 12GS/A unless they are of the type that already provide enough load to prevent you getting LAMPR warnings.

Unless BMW provide an optional ZFE update that copes with aftermarket LED bulbs, which seems unlikely.

 

[Bear]

An electrical engineer writes:

There is no point trying to measure the resistance of the new LED lights, you will only get confused and the figure will be pretty much meaningless because it is so much higher than the conventional bulbs.

What you have to do is add a load resistor in parallel with the LED unit (ok one each for the tail light and brake light) that takes sufficient current to convince the ZFE module that there is a normal bulb there and that it is working normally.

To do this you have to realise that there will be a threshold current that the ZFE uses to tell if the bulb is OK or not. This will be somewhere between the regular current used by the bulb and zero.

Tail light: takes about 5/12 = 0.4 Amp
Brake light: takes about 21/12 = 1.75 Amp

So I guess you need to waste about 0.2 Amp and 1 Amp respectively.

To do this from a 12V supply gives a resistance of

12/0.2 = 60 Ohms
12/1 = 12 Ohms

And this will dissipate

12*0.2 = 2.4 Watts
12*1 = 12 Watts

So you need resistors beefy enough to waste this much heat. Obviously if the ZFE threshold is set lower than my guess, you need to waste less current so can use higher resistance values and dissipate less heat in them.

But if you are doing this I'd check out what resistors you can get hold of. Something like a pack of five, 47 Ohms, 3 Watts would just about do it (using four in parallel for the brake light, and one for the tail light).

A retired electronics engineers writes:-

Whilst I agree with your method of estimating dummy load resistors the question I posed earlier regarding bulb resistance changing with temperature has not been considered. If the ZFE takes advantage of the thermal characteristics of bulb filaments (i.e. lower resistance when cold) to check for open-curcuits on start-up then the shunt resistors needed will be of such low value that I'd be cautious of their effect. Does the ZFE check for bulb failures only on startup (both my LAMPF warnings were), in which case I'm prepared to believe what I say, or can it check continuously (in which case I'm over-complicating the issue). I know LED bulbs are supposed to be reliable but are they really worth it when an ordinary bulb is cheap, easily found, and the bike warns you when its failed?

 

[Ali-bear]

LED bulbs are great because they don't blow as a result of physical trauma such as vibration on the tail of a vibration-prone bike like the GS.

You're probably right in that you may be able to get away with only a large (number of Ohms) shunt resistor to fool the ZFE. Maybe a single 470 Ohm, 0.5 Watt resistor would be enough.

 

[Silverstripes]

Hold on there chaps.

As I started all this, I thought it best to better clarify. Yes are talking 1200.

Yes we are talking replacement LED unit with clear lens, not an LED bulb. Although you do get the same problem, with the LAMPR warning.

Have been in communication with Another member who has contributed to this thread, He hs suggested a way forward using resistors and the value I should use. These have been ordered and I am awaiting arrival.

I will test when they arrive and then post the values used if the fix is sucessfull. This fix can then be considered for use by others, for both LED units and bulbs.

Just give me a day once the Resistors arrve and I hope to have a resolution.

 

[gzpainter]

Silverstripes...sorry I didn't want to destroy your thread with my problem with the LED bulb...just I believe that they are similar...
I am looking forward to hear from you as I am also planning to play with the resistors after a short talk with my "DIY-on-motorcycles" brother but it seems that you are already one step in front of me......

 

[littleredrooster]

yea...then where is the fuse box for the brake and tail light ....as I check all the manual and the only fusebox that it is mentioned is at the front right and is for the auxiliary lights.........

There ain't one. It uses an advanced wiring system called canbus which has a thing called a ZFE which senses and controls everything. If it detects a load which is outside of the expected range, it shuts that circuit down.

 

[SMB]

I have been looking at this thread and am concerned about some of the values quoted for the resistors.
Though the bike is nominally a 12V supply, with the alternator running, the supply voltage will rised to about 14V (unless the ZFE regulates the supply to the components, this I can't easily check on my 1200).
With a 12ohm resistor at 12V sure the power rating would be 12W however at 14V the power rating would rise to 16W. This will cause resistor to overheat. Problems for the plastic back end of the bike? I would recommend that a little over kill would be a good move, say 20W as this would match the rating of the normal rear lamp that it is replacing. (Basically the LED is a very low power unit).
SMB

 

[Silverstripes]

LED Rear light - LAMPR - The fix !!!!

For those following the thread on the fitting of my LED REar Light here is the fix:

You will recall the need to fix Resistors, to trick the bike electronics to think a bulb was connected rather than LED's thus avoid the LAMPR warning. This is due to the LED consuming less power thus the bike thinking that a bulb had failed.

After much Email discussion with SMB (My thanks to him) He suggested a value for the resistors.

I ordered these from Ebay, and settled for Aloy clad, for ease of mounting and better heat sinking.

The Brake light is 10 Ohm and 25 Watt.

The rear light is way over engineered with a 39 Ohm 50 Watt. The 50 Watt is the overengineered bit.

This big resistor on the rear light and hardly gets warm when the lights are on. The brake light does get warmer. I mounted both of these on the metal plate, which the bottom screw attaches to, to mount the plastic rear panel.

The resitors get air but cannot be seen from the exterior.

All works OK and no LAMPR warning..

Again my thanks to SMB

 

[giantbaby]

new puzzle......!!!!

Ive just upgraded to Les WASSELS Hid Headlights which i must say are awesome.......

The side light bulb looks yellowy and rubbish now so i bought an LED side light Bulb....

I have an 08 GSA and was wondering what resistor is needed in order to fool the Brain of the bike into thinking that the bulb is working and not the LAMPF symbol....

PS just a thought. when the bikes indicators were changed by BMW from Lamp to LED they simply plugged the bike into the Laptop and told it that it had LED indicators...... Could this be done for my problem here and also for the above problems ?????????????