Replaced my interior lights with 39mm led festoon replacements. Looks fantastic. However when the car is completely off, the leds still emit a very dim light? If I turn the interior light completely off (doesnt light up when door open) then the light also turns off.... any ideas? Is this a hazard to my battery? Im assuming it wont be as LEDs consume next to nothing power?

Lights on:


Lights off (but still will light up when car is unlocked/door open)

Did you try to leave the car 5 minutes and watch after ? (don't open a door, press remote key fob, etc...)

Seems to be a little residual current that flow through the LED... If it is a bulb this is not noticeable.

Nothing wrong with your car I think.
After minutes, your car modules are powering down to save battery, the LED should come off.

Stood there for about 2mins, but I'll leave it for longer. All I'm guessing is that when its in standby mode (car unlocks or door opens it turns on) there is a small amount of current flowing through, and because they are LEDs they are picking up on it?

Mkala said:

Did you try to leave the car 5 minutes and watch after ? (don't open a door, press remote key fob, etc...)

Seems to be a little residual current that flow through the LED... If it is a bulb this is not noticeable.

Nothing wrong with your car I think.
After minutes, your car modules are powering down to save battery, the LED should come off.

Click to expand...

left it for about 30mins.. went back out and they were flashing the dim light??

Strange. Do you have a multimeter to measure residual current ?

Do you have a picture of the LED, especially where electronics are ?

I'll see if theres a multi meter in the garage. Do you want a picture of the leds themselves? What do you mean by electronics, the light housing?

I've recently done they same bulb replacement and I have the same problem. I believe it's just a reflection, but I'm no expert.

Mkala said:

Strange. Do you have a multimeter to measure residual current ?

Do you have a picture of the LED, especially where electronics are ?

Click to expand...

Hm just checked the car after work.. about 5 hours after I turned the car off. No flashing? Maybe it stays on, flashes then completely turns off?

However when im driving there is a constant dim light. Doesnt really bother me as long as it poses no threat to the battery

Yeah I'm sure it won't harm the battery as long as you're not leaving your car unused for really long periods of a time. It's weird though in my car if I turn the interior light unit off with the switch the dim light goes off and then comes back on when the switch is flicked to on. But obviously you would want it left on for when you open your doors etc.

DazEvo said:

Replaced my interior lights with 39mm led festoon replacements. Looks fantastic. However when the car is completely off, the leds still emit a very dim light? If I turn the interior light completely off (doesnt light up when door open) then the light also turns off.... any ideas? Is this a hazard to my battery? Im assuming it wont be as LEDs consume next to nothing power?



Lights on:

Lights off (but still will light up when car is unlocked/door open)

Click to expand...

Mine did this it will be okay if u use the car daily for decent journey but if the car stand for like longer then 3week i wud say change it for a small led buld

DazEvo said:

I'll see if theres a multi meter in the garage. Do you want a picture of the leds themselves? What do you mean by electronics, the light housing?

Click to expand...

LEDs themselves exactly. With details on their electronic if we can see it.

DazEvo said:

Hm just checked the car after work.. about 5 hours after I turned the car off. No flashing? Maybe it stays on, flashes then completely turns off?

However when im driving there is a constant dim light. Doesnt really bother me as long as it poses no threat to the battery

Click to expand...

For the battery, it will not change anything if the current flow in a LED and you see it or if the current flow in a bulb and you don't see it.

Mkala said:

LEDs themselves exactly. With details on their electronic if we can see it.


For the battery, it will not change anything if the current flow in a LED and you see it or if the current flow in a bulb and you don't see it.

Click to expand...

pictures for you

Perfect !

Wow ! No resistor ? No other component than LEDs ? Unbelievable.
Should work 10 hours at best... :yuck:

Did you manage to measure the current when dimly light ?

Should be very low, for information with a 12V source I can light dimly a LED through... my fingers

Mkala said:

Perfect !

Wow ! No resistor ? No other component than LEDs ? Unbelievable.
Should work 10 hours at best... :yuck:

Did you manage to measure the current when dimly light ?

Should be very low, for information with a 12V source I can light dimly a LED through... my fingers

Click to expand...

i havent seen any of these festoon bulbs have resistors?? does it pose a risk to my car?

I checked ebay and you are right... sh**ty world and low costs part are kings on Internet. Really don't understand how these LEDs can work more than a few days.

For your car ? No big worry, hopefully Fiat puts fuses before giving power to all components. So in case of problem it will work for you.
If Fiat made cars like chinese make LEDs, they will burn in less of one week.

Perhaps with resistors or a regulator chip, dimming issue can goes out. I will see if I can work on this, interested with LEDs too.

Mkala said:

I checked ebay and you are right... sh**ty world and low costs part are kings on Internet. Really don't understand how these LEDs can work more than a few days.

For your car ? No big worry, hopefully Fiat puts fuses before giving power to all components. So in case of problem it will work for you.
If Fiat made cars like chinese make LEDs, they will burn in less of one week.

Perhaps with resistors or a regulator chip, dimming issue can goes out. I will see if I can work on this, interested with LEDs too.

Click to expand...

ah ok... even though the interior lights aren't covered by the canbus system.. maybe canbus festoon leds could fix the dim/flashing problem?

If anyone finds some bulbs which will work properly can you link me? I have the same problem

DazEvo said:

ah ok... even though the interior lights aren't covered by the canbus system.. maybe canbus festoon leds could fix the dim/flashing problem?

Click to expand...

Not covered by CANBus, exactly. But resistors have two roles in LED bulbs :

1. Current limitation - a LED is driven by current not voltage. You must have a current source for LEDs, but for low power it is acceptable to have limiting resistors.

2. For "CAN Bus" LEDs (which mean nothing by the way), they add resistors to rise LED consumption. This way, car electronics see a normal current consumption and does not light the warning on dash.

I will try to work on this in next weeks, as I am interested by interiors LEDs and I like electronics

Out of interest did you find a solution to this? as my mk2 punto has just started doing this.