Technical LEDs in tail light have fault light on dash

[daz4mile]

Hello,

Just put LEDs in the rear cluster. They have built in resistance.

With these LEDs in only the brake lights or the indicators or both, there is no fault light on dashboard. (Brake pressed, indicators on)

However, when these LEDs are put into the tail lights a fault light appears on dashboard. I have taken these out and put the original incandescent bulbs back into the tail lights. (No dashboard fault light)

The original incandescent tail light bulbs are half the size of the other original bulbs. Does this point to why the LEDs in the tail lights show a fault light on the dashboard? Any ideas much appreciated.

Serendipitously I might leave the original incandescent tail light bulbs in, as now there is more distinction between these and the LED brake lights when illuminated.

Look forward to reading any replies
Kind regards

Darren

 

[simon_16vpunto]

Unfortunately, fiats are very particular and get upset about led bulbs, and throughout the last 20 odd years (and still now actually with my doblo van) I have tried and failed with error free led’s and putting resistors in also.

My 29 year old Punto doesn’t give a toss about led’s as there is no canbus in that, but the newer stuff (mk2 Punto > to present day), computer says no.

I’m just living with the bulb error on the dash now.

 

[daz4mile]

Unfortunately, fiats are very particular and get upset about led bulbs, and throughout the last 20 odd years (and still now actually with my doblo van) I have tried and failed with error free led’s and putting resistors in also.

My 29 year old Punto doesn’t give a toss about led’s as there is no canbus in that, but the newer stuff (mk2 Punto > to present day), computer says no.

I’m just living with the bulb error on the dash now.

These are the LEDs with resistor I bought from Amazon, about £20 a pair. They work (no fault light on dashboard) in the brakes but not the tail light.

Will probably give the other pair to my dad or keep as spares for the brake light

 

[simon_16vpunto]

Yeah, it’s weird, only some lighting circuits are wired up to canbus.

I have led daytime running lights in my doblo and led number plate lights, which both throw up faults.

High level brake light, reversing lights, front fogs, dipped beams are all led/ hid and it’s fine with them.

Same as my old 595 Abarth, and even my old 2005 Punto mk2b.

 

[PuntoHowTo]

Indicators and brake lights are 21W ? and tail lights are usually 10W.... thats probably the reason the bulbs will not go in without causing errors.

Aside from the fact that these are not technically legal to use on the road in the uk and there is probably some disclaimer on the box saying that.

the whole point in brake lights and tail lights is that brake lights are much brighter to warn the car behind you are braking, so if you fit all the same bulbs to the tail lights, then the car driving behind may not notice your brake lights coming on, or more likely you'll be blinding everyone following you all the time with your brake light level brightness in your normal tail lights, and potentially draw some unwanted attention from the police.

IT would definitely fail the MOT with no distinction between tail and brake lights.

In summary the bulbs you have, are set with the resistance for a 21W bulb used for brake and indictors and not for the normal tail lights.

Worst still if you are braking for a corner, with your indicator on, at night, with all bulbs lit, then the wiring to the bulbs, mainly the earth is likely to end up carrying more current than it is rated for and you could at best burn some wires or at worse start a fire or damage the body computer.

LEDs can generate a huge amount of heat in lights of this brightness and could also cause damage over time, melting or burning the tail light unit.

Mk2 punto's are notorious for poor wiring to the rear lights.

 

[varesecrazy]

Indicators and brake lights are 21W ? and tail lights are usually 10W.... thats probably the reason the bulbs will not go in without causing errors.

Aside from the fact that these are not technically legal to use on the road in the uk and there is probably some disclaimer on the box saying that.

the whole point in brake lights and tail lights is that brake lights are much brighter to warn the car behind you are braking, so if you fit all the same bulbs to the tail lights, then the car driving behind may not notice your brake lights coming on, or more likely you'll be blinding everyone following you all the time with your brake light level brightness in your normal tail lights, and potentially draw some unwanted attention from the police.

IT would definitely fail the MOT with no distinction between tail and brake lights.

In summary the bulbs you have, are set with the resistance for a 21W bulb used for brake and indictors and not for the normal tail lights.

Worth noting also..

The 188 punto didn't use "standard" bulbs..
The 21/5 bulbs may have worked but I seem to recall whatever you got from Halfords. Etc put on the dash warning.. As the wattage was incorrect

Your "corrected" LEDs are no doubt set for the Norm.. Not the rarity of the 188

The

 

[deafmazter]

Indicators and brake lights are 21W ? and tail lights are usually 10W.... thats probably the reason the bulbs will not go in without causing errors.

Aside from the fact that these are not technically legal to use on the road in the uk and there is probably some disclaimer on the box saying that.

the whole point in brake lights and tail lights is that brake lights are much brighter to warn the car behind you are braking, so if you fit all the same bulbs to the tail lights, then the car driving behind may not notice your brake lights coming on, or more likely you'll be blinding everyone following you all the time with your brake light level brightness in your normal tail lights, and potentially draw some unwanted attention from the police.

IT would definitely fail the MOT with no distinction between tail and brake lights.

In summary the bulbs you have, are set with the resistance for a 21W bulb used for brake and indictors and not for the normal tail lights.

Worst still if you are braking for a corner, with your indicator on, at night, with all bulbs lit, then the wiring to the bulbs, mainly the earth is likely to end up carrying more current than it is rated for and you could at best burn some wires or at worse start a fire or damage the body computer.

LEDs can generate a huge amount of heat in lights of this brightness and could also cause damage over time, melting or burning the tail light unit.

Mk2 punto's are notorious for poor wiring to the rear lights.

We got someone with knowledge here, ur 100% right sir!