Number plate lights not working.

[FatbobAde]

Hello everyone, I hope that I may plug into the collective knowledge pool for my current problem.

My wife took our 2020 Leaf Tekna to the local MOT station for its annual check. Everything was ok except that the number plate lights on the rear were not working, so it was a MOT failure. We still have ticket for a week or so, so hopefully I can get it sorted before it is off-roaded legally.
Today I have stripped down the tailgate trim to access the lamp holders and with the limited diagnostics at my disposal and a 2°C outside temperature I have ascertained the following with ignition on and sidelights selected:-
It is not the lamps. I have changed for new and verified the lamps continuity. Of the old lamps one was good and one was bad but not blackened (it looked ok but metered out as open circuit).
It is not the lamp-holders, there is continuity across them and the metal conductors are bright and corrosion free.
It is not the fuse, at least by the fuse configuration diagram at my disposal, the fuse is intact and other lights on the common circuit are energised. I have pulled and replaced the fuse to verify.
I cannot detect any voltage at either of the lamp-holders.
The cables are black/brown and black/blue and disappear into the tailgate loom and then into the vehicle body at high level LHS.

I cannot find a more detailed circuit diagram online to guide me towards any connectors or multi pin plugs etc., nor can I find anyone else asking for help about this problem previously.

Is there a possibility that the circuit could have been switched off by a central control unit or do the brown and blue become common at another point in the loom that I can access?
If the former, can it be reconnected via OBD11?
If the latter, is splicing a +12v wire from somewhere else on the sidelights circuit to that point feasible?

Any help would be much appreciated before I have to get it to the nearest Main Stealers and have my pants pulled over my head financially…..

Cheers

 

[Bombastinator2]

Well I’ve always been a fan of “the IT crowd” method. “Is it plugged in” and “have you turned it off and on”. Do the bulbs have intact filaments? Is there evidence of corrosion?

Another thought: how is this a bad thing?

There are people who have had their phone die and immediately fallen to their knees and thanked god.

 

[ACDCPhilip]

Hello everyone, I hope that I may plug into the collective knowledge pool for my current problem.

My wife took our 2020 Leaf Tekna to the local MOT station for its annual check. Everything was ok except that the number plate lights on the rear were not working, so it was a MOT failure. We still have ticket for a week or so, so hopefully I can get it sorted before it is off-roaded legally.
Today I have stripped down the tailgate trim to access the lamp holders and with the limited diagnostics at my disposal and a 2°C outside temperature I have ascertained the following with ignition on and sidelights selected:-
It is not the lamps. I have changed for new and verified the lamps continuity. Of the old lamps one was good and one was bad but not blackened (it looked ok but metered out as open circuit).
It is not the lamp-holders, there is continuity across them and the metal conductors are bright and corrosion free.
It is not the fuse, at least by the fuse configuration diagram at my disposal, the fuse is intact and other lights on the common circuit are energised. I have pulled and replaced the fuse to verify.
I cannot detect any voltage at either of the lamp-holders.
The cables are black/brown and black/blue and disappear into the tailgate loom and then into the vehicle body at high level LHS.

I cannot find a more detailed circuit diagram online to guide me towards any connectors or multi pin plugs etc., nor can I find anyone else asking for help about this problem previously.

Is there a possibility that the circuit could have been switched off by a central control unit or do the brown and blue become common at another point in the loom that I can access?
If the former, can it be reconnected via OBD11?
If the latter, is splicing a +12v wire from somewhere else on the sidelights circuit to that point feasible?

Any help would be much appreciated before I have to get it to the nearest Main Stealers and have my pants pulled over my head financially…..

Cheers

According to a circuit diagram I have for a 2023 model, both rear number plate bulbs are wired in parallel as you might expect.
They connect back to the rear Left Hand combination lamp tail light pin 6.
I doubt your 2020 model will be different.

So if that left tail light light is still working it must be a broken wire somewhere between the two.

The tailgate movement stresses the wiring everytime it is opened, so I would look in the rubber bellows at the top of the tailgate first.
It wouldn't be difficult to just renew this wire.

 

[FatbobAde]

According to a circuit diagram I have for a 2023 model, both rear number plate bulbs are wired in parallel as you might expect.
They connect back to the rear Left Hand combination lamp tail light pin 6.
I doubt your 2020 model will be different.

So if that left tail light light is still working it must be a broken wire somewhere between the two.

The tailgate movement stresses the wiring everytime it is opened, so I would look in the rubber bellows at the top of the tailgate first.
It wouldn't be difficult to just renew this wire.

Many thanks for the response, everything else is fine so a broken wire was my guess as to the culprit. I’ll get the LHS lamp off and have a look. Does pin 6 have both bl and br or is there another joint?
Thanks again

 

[FatbobAde]

Well I’ve always been a fan of “the IT crowd” method. “Is it plugged in” and “have you turned it off and on”. Do the bulbs have intact filaments? Is there evidence of corrosion?

Another thought: how is this a bad thing?

There are people who have had their phone die and immediately fallen to their knees and thanked god.

 

[woeful]

Worth checking continuity to chassis for one pin of each light (the black wire, possibly) and for +12V measured at each when the tail lights are on. That should, with luck, identify whether it's the +12V feed shared with one of the sidelights or an earth connecting wire which has broken. The wiring diagram for the older shape of Leaf suggests there are 3 separate +12V wires out of their junction, one each for the tail lamp and the two number plate lamps.

This message is based only on a wiring diagram which may not apply to your model. Trust it as much as you would any other rubbish on the internet.

 

[ACDCPhilip]

Many thanks for the response, everything else is fine so a broken wire was my guess as to the culprit. I’ll get the LHS lamp off and have a look. Does pin 6 have both bl and br or is there another joint?
Thanks again

My circuit diagram doesn't show wire colours so unfortunately I can't help you there.