Hi there

I put some nice 7w leds lamp in DRL optics

but the diagnosis check always shows - replace lamp.

 

I put a dummy resistor and the error code disappeared,

but is ridiculous to fake the diagnosis test with extra load (waste of 5W)

 

I want to have more light (7W leds are more efficient than gas bulb) with less current from battery.

 

How can I disable diagnosis test to DRL lamps with VCDS software.

 

Thanks,

Loads of threads on this subject already, do a search. I think you will find that unless resistors are fitted (which get very hot) you will not find a solution

The only cure, until someone actually makes an LED DRL that works, is to fit a resistor.

 

And wow, what a waste 10w's is going to be! :think:  :wonder:  :think:  :wonder:  :think:

 

Editted for speling mistake!

They only cure, until someone actually makes an LED DRL that works, is to fit a resistor.

 

And wow, what a waste 10w's is going to be! :think:  :wonder:  :think:  :wonder:  :think:

Bet Apollo 13 wouldn't have thought like that

...Editted for speling mistake!

Yore being pedentic again...

Yore being pedentic again...

Wot, me? :giggle:

Now the dealer tells me that my dynamic cornering headlights don't work because I have fitted LED DRL's, an they won't even run a code check to support my warranty claim that the headlight control module is faulty.....

 

Why should they?

You have altered the lighting specification of the vehicle, so until you return it to standard spec they are not liable.

Your choice.

So how little do I have to do to alter the lighting spec ? Would they get uppy about the LED boot light ? Anyway the original bulbs are going back in at the weekend.

How about this for an idea to avoid CANBUS errors - put a small wattage load resistor for the CANBUS to sense, but take it out of circuit with a relay when power goes to the bulb

Whoops circuit error, this might work

So how little do I have to do to alter the lighting spec ? Would they get uppy about the LED boot light ? Anyway the original bulbs are going back in at the weekend. How about this for an idea to avoid CANBUS errors - put a small wattage load resistor for the CANBUS to sense, but take it out of circuit with a relay when power goes to the bulb

 

Whoops circuit error, this might work

 

The Bulb Failure system senses the resistancce of the circuit, therefore your idea will not work.

The standard method to get rid of the "problem" is to fit a resistor across the 2 leads all the time.

Problem is the central electrics unit (j519) which controls the lights etc was never designed to handle big ballast resistors FACT!. A ballast resistor can put a massive initial "load" on the circuit and can cause issues with the central electrics, Ever wondered why these so called canbus friendly ballast resistors get so hot?. The way the vag system works is everytime you fire the ignition it sends a "cold start diagnosis" down the circuit to test the bulbs (basically checking for a blown bulb) and the problem is when you fit led bulbs the cold start diagnosis cannot sense any "load" on the led compared to a conventional bulb and that's when you get the bulb warning lamp on, People then fit these ballasts to trick the system but in actual fact they are potentionaly overloading the system and that's when problems can occur.

With a relay and a 10ohm resistor, the 'cold start diagnosis' sees the resistor as a bulb filament. When there is 12v across the bulb it lights up and the resistor disconnects, so the circuit only takes the relay current and the small LED current. If that doesn't work then the light control unit MUST be current sensing. I have yet to prove it by experiment. My relay coil meters at 502ohm btw. The 'ballast resistor' in this case only takes current when the light is switched on and is then immediately disconnected by the relay, so it would have little heat to dissipate and therefore need only be low wattage.

The normal P13W bulb has a cold resistance of about 2.7 to 3 ohms, when it is hot 21w at 13.6v is a current of just over 1.5A, which works out at 8ohms, so a 10ohm ballast resistor would not load the control unit any more than a P13W filament bulb.

As the cold resistance of a bulb is lower than the hot then there is an initial current surge in the millisecond (ish) when the bulb heats up. a resistor presents a more constant current profile.

All these assertions are based on Ohm's Law V = I*R and W = I*V which for DC circuits has proved a good friend to me for years.

As I said, I have yet to try this out. This weekend I have a command performance with a bucket of paint, a roller and two rooms.

Cheers,

Rob

Using a relay and a resistor still wont work, because the system is constantly monitoring for bulb failure as well as the initial cold start diagnosis system which your relay and resistor idea is trying to trick, So when your relay has switched off which in turn has switched your ballast off the bulb warning will come on to tell you that a bulb has blown. These so called can friendly ballast resistors are bad for these new central electric units due to the initial spike loads  being made by the resistor. When you consider the ballast is basically a winding of resistive wire it should make anyone with a bit of technical know how wary of playing with these systems. Ive seen quiet a few disasters with these resistors being fitted, Melted wires causing electrical fires, blown central electric units, and other circuits being affected.

As previously said, it will NOT work!!

The bulb failure system senses the resistance of each circuit CONTINUOUSLY, not just on first switching it on.

Please read my post properly before blowing a fuse !

Please read my post properly before blowing a fuse !

I think you will be the one blowing a fuse or even worse your central electrics unit if you keep messing around with these systems, and then you wonder why the dealer will not look at your car.

LED DRLs standard fit on the FL (Elegance & L&K).........sorry, just thought I would mention it.

Please read my post properly before blowing a fuse !

 

Your exact words:

 

With a relay and a 10ohm resistor, the 'cold start diagnosis' sees the resistor as a bulb filament. When there is 12v across the bulb it lights up and the resistor disconnects, so the circuit only takes the relay current and the small LED current. If that doesn't work then the light control unit MUST be current sensing. I have yet to prove it by experiment. My relay coil meters at 502ohm btw. The 'ballast resistor' in this case only takes current when the light is switched on and is then immediately disconnected by the relay, so it would have little heat to dissipate and therefore need only be low wattage. The normal P13W bulb has a cold resistance of about 2.7 to 3 ohms, when it is hot 21w at 13.6v is a current of just over 1.5A, which works out at 8ohms, so a 10ohm ballast resistor would not load the control unit any more than a P13W filament bulb. As the cold resistance of a bulb is lower than the hot then there is an initial current surge in the millisecond (ish) when the bulb heats up. a resistor presents a more constant current profile. All these assertions are based on Ohm's Law V = I*R and W = I*V which for DC circuits has proved a good friend to me for years. As I said, I have yet to try this out. This weekend I have a command performance with a bucket of paint, a roller and two rooms. Cheers, Rob

 

The bulb failure system CONTINUOUSLY moniters the system, not just at start-up. your idea will only "work" on the initial switching on of the circuit and will therefore NOT work.

 

I agree with Sherlock, it is no wonder the dealer is refusing to deal with your "problem" as a warranty matter.

These were the words that are relevant :-

 

 

If that doesn't work then the light control unit MUST be current sensing. I have yet to prove it by experiment.

 

So you might understand that I agree with you until I can find a better way of overcoming the bulb failure indication.

 

For Sherlock, I agree that wirewound ballast resistors are a crude expedient, but if they are not bifilar  or Ayrton-Perry wound then they would have an undesirable inductive component. This would manifest itself as an impedance at switch on as the build up of the magnetic field opposes the current.  The spike would be formed when the current is switched off as the collapsing magnetic field generates a back-emf spike. This is easily quenched with a capacitor or diode.  This back-emf pulse is more likely to damage the J519 unit. ALL THIS PRESUMES  that you are not using too low a value of ballast resistor that would fry the control unit by drawing too much current.

 

The purveyors of these LED bulbs and ballast resistors maintain that they are perfectly OK, but I have severe doubts, that is why I seek an alternative.

 

One alternative is that if the control unit seeks a bulb, let it find one by using a filament bulb as a ballast.

 

My warranty problem is that the dynamic headlight control unit (J745) which activates the headlight direction servos is not responding to the steering angle sensor. The servos are OK as they go through their start-up dance routine.

 

Skoda have fitted sidelight bulbs with a blue envelope and xenon foglight H7 bulbs with a blue tint are easily available, but does anybody know where I can get P13W (blue) bulbs for the DRL's ?

Think we all need a translator.

I get the impression he is saying that he doesn't trust the resistor system that has been used by many, many people here and elsewhere with absolutely no problems, and thinks that he can come up with a better system. 

 

And no, I've never heard or seen a "blue" P13W bulb.

It is Sherlock that doesn't trust the resistor system. If there is a better after market solution, I would like to find it (and patent it). This thread is starting to go round in a big circle (unlike my headlamps).

There MAY be another solution - to code out the OBD check for the DRL bulbs, but you would probably need a dealer to do that, IF IT CAN BE DONE AT ALL.

Think we all need a translator.

 

Think all we need is a transistor

It is Sherlock that doesn't trust the resistor system. If there is a better after market solution, I would like to find it (and patent it). This thread is starting to go round in a big circle (unlike my headlamps). There MAY be another solution - to code out the OBD check for the DRL bulbs, but you would probably need a dealer to do that, IF IT CAN BE DONE AT ALL.

 

It has been tried on the Yeti, and no-one has found a way to do it.

And most dealers will not touch VCDS work!