2

I had my car serviced yesterday at the dealer - a number of minor issues were reported

  1. Wipers are smearing - mainly due to road dirt as I had only recently replaced them
  2. Water ingress in tail light - its an LED Sealed unit so not a lot I can do about that
  3. Dim LED high level brake light.

My understanding is that LEDs are an all or nothing type of shot - so the circuitry itself must be ok, and rather it must be a low power (i.e. poor connection) issue.

Unfortunately I haven't had a chance to look at it in daylight so wont be able to confirm, but could there be other reasons for a brake light (specifically LED) to appear dimmer than it should?

Car is a late 2013 SEAT Leon.

|improve this question|||||
2

LEDs are not all or nothing, your typical LED car light has several LEDs in it, so you can have partial failures if one or more go bad. LEDs last a very long time, however they do break early sometimes, and the circuitry is not bulletproof either, so you could have a partial failure of the unit.

The failure modes that would make sense are:

  1. Some LEDs have failed: this is unlikely, one I could see, more than one would be unusual
  2. LED block failure: On the LED lights I've seen the LEDs are not all on the same driver, they are usually separated in different blocks that run in parallel electrically. A failure of one of the blocks would take out all the lights on that block
  3. Insufficient power: if the regulator which supplies power to the unit is sagging, that is not supplying enough power I could see the lights being dim

My money would be on #2, however #3 is easy enough to test, just disconnect the wiring harness and use a multimeter to check the voltage.

|improve this answer|||||
  • I've done some digging - apparently theres a diode before the power splits to the three blocks of LEDs and it can go bad, I'll confirm early next week. – Mauro Oct 13 '17 at 13:57
  • Sounds about right. You may or may not be able to fix it, these days circuit boards can be very tricky to work on, requiring more than a soldering iron and some desoldering equipment, however it may be worth a shot if the part is expensive to replace. – GdD Oct 13 '17 at 14:03

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.