Technical Headlight unit LED DRL's

[rayc]

My one month old Ducato has 3 LED units out of 16 failed in the passenger side headlight unit. The whole unit is being replaced under warranty.
Is replacing the whole unit the only repair option especially when outside warranty?
The DRL's are also used in dimmed mode as parking and side lights. how many units would have to fail for it to be illegal?

 

[g8rpi]

My one month old Ducato has 3 LED units out of 16 failed in the passenger side headlight unit. The whole unit is being replaced under warranty.
Is replacing the whole unit the only repair option especially when outside warranty?
The DRL's are also used in dimmed mode as parking and side lights. how many units would have to fail for it to be illegal?

Yes, currently the only recognised repair option for LED light units with failures is to replace the whole assembly.
There are currently no approved replaceable LED "lamps" or even a standard for them.


You might think that it's possible to dismantle the unit and replace the filed part, but typically the assemblies are welded or glued together. Additionally where do you get the new LED? Even if you identify the right part number they have slight variation in performance and the better ones are graded for brightness (and colour if applicable) and only ones of the same grade are used in one unit.


Robert G8RPI.

 

[CDK]

LED chips only fail when they are not in thermal contact with the heat spreader under them. Usually the surface is a bit warped or silicone is locally missing.
If 3chips have already failed, more will follow, so the whole unit must be replaced. A LED unit that has been properly assembled will outlive the vehicle.

 

[HughJampton]

The DRL's are also used in dimmed mode as parking and side lights. how many units would have to fail for it to be illegal?

...an interesting question. The MOT manual is largely silent about DRLs, except for the explicit paragraph:

Daytime running lamps are not testable unless
they replace the front position lamps. Where this is
the case, they should dim when the position lamps
are switched on and may extinguish when the
headlamps are switched on.

In your case, it appears that they do perform the function described, so it may then well be that the general rules on lighting apply, i.e. it would fail if it were "inoperative or less than 50% of the light sources illuminating"

I'm fairly happy that my X/290 has the non-LED DRLs

 

[g8rpi]

LED chips only fail when they are not in thermal contact with the heat spreader under them. Usually the surface is a bit warped or silicone is locally missing.
If 3chips have already failed, more will follow, so the whole unit must be replaced. A LED unit that has been properly assembled will outlive the vehicle.

That's a bit of a bold statement. While its true that lack of required heat sinking of power LEDs will cause failure, it's not the only failure mode. Bond wires and solder joints can fail, PCB traces crack and the current limiting circuit (just a resistor in simple lights) can fail. I've seen more joint and drive circuit failures than actual LED failures in faulty LED arrays I've investigated.


Robert G8RPI.

 

[CDK]

Please note I mentioned 'LED chips'.
Of course all kinds of peripheral faults can mean end-of-life for a complete (sealed) LED unit.