I posted a few years back about a bulb failure in one of my DRL lights. It is not really a failure of the bulb but of the solder pip on the bulb being fretted away by vibration of the plastic under trim. It is the reason why the manufacture fits a non standard bulb with a thicker anti vibration element, type PY21W SLL.

 When you get a bulb failure for DRL it is unlikely that you need to change the bulb, only reflow the solder (and perhaps add a little more solder) on the pip. It will then last another 25+k miles.

 

Thought you may like what my bulb looked like when I took it out to reflow the solder:-

 

The reason that happens is they use unleaded solder these days, remove the old solder and use a good quality leaded solder to resolder it, that should do it.

26 minutes ago, Radiogaga said:

remove the old solder and use a good quality leaded solder to resolder it, that should do it.

Once the old solder was molton I added in some leaded solder.

However, I know that this is not the complete answer as leaded solder tends to spread out more under pressure and vibration as had happened on one of my previous repairs.

It's the heat from the bulb being continually on.

 

Leaded solder has a lower melting point than the unleaded type so it is to be expected that it will more readily deform.

 

A smear of petroleum jelly may help reduce microscopic abrasion, deter oxidation and prolong usefulness.

 

Ensure the bulb holder contact is clean and smooth.

Doesn't anyone these days know what the silver foil in a fag packet is for? 😆

 

The silver foil that probably has been removed since I gave up smoking 42 years ago!

5 hours ago, pikpilot said:

Once the old solder was molton I added in some leaded solder.

However, I know that this is not the complete answer as leaded solder tends to spread out more under pressure and vibration as had happened on one of my previous repairs.

See if you can find a leaded solder with slightly higher tin content than normal - it has a higher melting point and is harder.

Plumbing solder is harder than electrical solder.