Hi, I have purchased some L.E.Ds from ebay with built in resistor circuitry I have fitted them to my Octy and now the bulb warning light is on due to the low voltage drop on the L.E.Ds. They come on for a second or two then turn off and log a fault in memory.....

2 Faults Found:

02394 - Parking Light Left Front (M1)

012 - Electrical Fault in Circuit

Parking Light Right Front (M3)

012 - Electrical Fault in Circuit

Is there a way to trick the ECU or deactivating the bulb monitoring some how?

You need to put another resistor in-line with the led to fool the system into thinking it has the same resistance as a standard bulb.

Some previous threads on here somewhere before.

Thanks for the reply back, ill take a look do you have a link to the sites?

I've fitted a pair of those 5 led-in-1 bulbs to my fabia and not had the same symptoms. Not sure if the octy system is different though.

The Octy II will extinguish said LED after a second or 2 and you'll get a bong and a lightbulb on the dash. I fitted shunt resistors about a year ago and they have been fine.

Linky

I scotchlocked my resistors to the OEM wiring just off the W5W fitting and routed the LED cabling through one of the (fiddly) rubber vents in the back of each light fitting. They get VERY hot so need to be clear of anything vulnerable and attached to something metallic that can act as a heat sink.

Hi, where would I get a shunt resistor from what resistor value will i need. I thought if i could deactivate the cold bulb monitoring i wouldnt have to use a shunt resistor?

I'm not sure disabling the cold monitoring will help, IIRC the cold monitoring checks the bulb condition when it is off by running a very low amount of power through it. The current will still be monitored when it is switched on and will throw a wobbly. I have posted a link for the resistors.

you could leave the original bulbs in and wire in a strip led off the wires that way you wont get a bulb warning.

Switch off the cold monitoring of the lights in question and they will work fine without fitting resistors (As long as they are suitable for 12V)

I have switched off the cold bulb monitoring for the side lights but still dont work and bulb warning light on dash display. The L.E.Ds are supposed to have built in resistor circuitry I think this may be where the fault lies.

dstev2000 thanks for the link.

No problem, the bulb failure system most likely monitors the actual load through the bulb rather than the internal resistance, it won't detect any 'spoof' electronics in the LED as it's looking for the current draw of a W5W bulb.

A resistor is the only reliable way of getting LED's to work properly.

A resistor is the only reliable way of getting LED's to work properly.

Which sort of negates two of the advantages of using LEDs - lower current draw and less heat generation :confused:

Here's a link to a typical load resistor kit you can get. Seems quite tidy.

2 x LED SIDELIGHT W5W R5W BA9S 25W on eBay, also Other Lights Accessories, Lights Lighting Accessories, Car Tuning Styling, Cars, Parts Vehicles (end time 19-Nov-08 16:04:17 GMT)

Rgs

Which sort of negates two of the advantages of using LEDs - lower current draw and less heat generation :confused:

Stuff current draw and heat generation, the only reason you fit LEDs is for the appearance

Edited 2 November, 200817 yr by dstev2000

Hi dstev2000, purchased those resistors from the link you sent me thanks when i fit them whats the best way to insulate the resistors dont want them shorting out on the body of the car?

The resistors themselves are actually inside the gold coloured heat sink so no fear of shorting to the chassis. If they are the same ones I use (they look identical) they will have plastic heat shrink on the metal teminals that prodtrude from each end and connect to the included cables.

As long as none of the insulation is damaged you will have no electrical problems.

Hi, I have now connected and wired in the resistors I purchased connecting them into the live side of the side lights they come on for a few seconds then go out which puts the bulb warning light on, dstev2000 is there anorther way to wire these in so thet can work?

Could the bulb warning light be turned off in vag com

Hi, I have now connected and wired in the resistors I purchased connecting them into the live side of the side lights they come on for a few seconds then go out which puts the bulb warning light on, dstev2000 is there anorther way to wire these in so thet can work?

http://briskoda.net/octavia-ii/daylight-driving-lights-fuel-economy/124254/#post1452039

Hi, I have now connected and wired in the resistors I purchased connecting them into the live side of the side lights they come on for a few seconds then go out which puts the bulb warning light on, dstev2000 is there anorther way to wire these in so thet can work?

Can you give some more details about how they are connected?

Provided the resistors are correct one can only assume incorrect wiring.

Where have you mounted the resistors? they get f'kin hot so they need to be mounted on something that is metal to act as a heat sink.

As long as the resistors are mounted in parallel to the LEDs you will be fine.

If the are in series with the LEDs you will have problems.

Double check things with this sketch:

Hi dstev2000, ive wired them in series thats why they dont work ballsed that up then ill rewire them and report back id of thought being in series the resistor would of worked why do they have to be in parrlel across the resistor?

Did you read my post here?

There is all the information you need.

I will try to explain in more details now.

The computer expects to see some nominal power/current of the bulb's electrical chain.

Let talk about 10W traditional bulb.

If you want to use 3W LED lamp instead, the computer will not see enough power consumption, and will decide the bulb have blown.

We have do draw additional 7W on this electrical chain to restore the original power drawn.

If you install the resistor in series, you will make things worst, because the power will goes even lower than 3W (and LED will become dim).

You have to install the resistor in parallel to draw this additional 7W power.

This lead to resistor 24 ohm(see the table and formula in my post), dissipating 7W power.

Now you must take care about power rating of this resistor - it must be at least 10W in nominal.

Ceramic wired resistors or special aluminum packaged are preferable.

You have to take care with heat dissipation also:

Where have you mounted the resistors? they get f'kin hot so they need to be mounted on something that is metal to act as a heat sink.

Finally, the pins of the resistor would be very hot also.

Try to not solder them, it's better to use luster joint (sorry , do not know how to say in English).