If a LED taillight has one or two of the small LEDs burnt out, does it still pass for inspection?

UPDATE: As of March 2018, PennDOT has released a new bulletin giving new guidance on inspection criteria for LED lighting. They are now recommending a new policy:

"PennDOT’s policy regarding LED lighting is to allow its certified and authorized safety inspection technicians who perform vehicle safety inspections to exercise their discretion and to pass or fail LED light fixtures based on the technicians’ determination of whether the fixture emits sufficient light to be safe. In making their safety determination, technicians would be required under the existing regulations to fail a fixture when none of the diodes are working, and the Department recommends against passing a fixture when more than half (50%) of the diodes are not working. The 50% threshold was suggested by the IAB based on its members’ knowledge of and experience with LED fixtures."

PennDOT acknowledges that this policy helps reduce the burden of costly repairs on vehicle owners, however it also acknowledges that this policy does not change the law and law enforcement could interpret the regulations differently.

Either way, inspectors should be happy to know that PennDOT has published this updated policy allowing technicians to use their discretion when inspecting LED lighting.

Previous Guidance (as of October 2016):

In Subchapter E, F, G and H it states that the vehicle should be rejected if;

"An exterior bulb or sealed beam, if originally equipped or installed, fails to light properly." (It does have the exception of ornamental lights which are illegal to be on the vehicle on the first place.)

The question then relies on the fact that if a single, small LED is burnt out, does it still "light properly"?

This is a tough question so I took it to PennDot officials. The PennDot representatives acknowledged that this might change in the future, but currently, the way the law is written, “If one diode is out in a tail light, the light fails inspection”. This is not what I have heard in the past but that was never in writing and I agree that what is currently in the regulations does not leave an allowance for any portion of the light to be out.

I also contacted “Grote”, a popular LED light manufacturer and while they can’t specify or decide legal requirements, they did say that for warranty purposes, a single LED being out is a problem and the light requires replacement. They also confirmed that if a lamp “has 7 diodes it needs all 7 diodes.”. In some ways this is similar to the situation with lugnuts. A pickup truck might have 8 lugnuts on a wheel and all must be present to pass. It does not matter that if one is missing it still has 7 which may be more than other vehicles. If the vehicle did not need all 8 lugnuts they would not have made it that way. I guess with LED lamps if it did not need all the individual LEDs they would not have made it that way.

I know this is likely to cause a lot of vehicles to fail PA safety inspection but until the law is changed and different criteria is established all LEDs need to be functioning in a lamp for it to be working properly. (The only exception might be an OEM that sets a criteria allowing some LEDs to be out but the light to still be considered as functioning "properly". At this point in time I do not know any OEMs with this specification.)