2019 Leon Rear Indicator Issue - Water Ingress?

[leon_mike]

Took car for Service at Seat Dealer today (partner drove I followed in my other car), they washed it and we went to collect. Following partner home I noticed whenever my she indicated the opposing side red LED (the one that switches to become indicator) of the light units on the boot flashes red.

Took car back to dealer and they took boot rear light cover off and there was water present. They said the light seals were probably gone, but considering its not rained today and the car was just jet-washed its a bit of a co-incidence.

After about 45 minutes of looking (and with the dealership about to close) service tech said the connectors to the rear lights units were showing corrosion, he had tried to clean but either that or a poor earth was probably the issue.

Checked tonight at home. Sprayed connectors with electrical contact cleaner......no difference.

Disconnect right light connection (the one with corrosion) - indicate right....left top red LED segment flashes red.
Reconnect right light and disconnect left - indicate left.....right top LED segment flashes red
Turn on Hazard lights and the both red LED segments turn off and amber shows correctly
Lock/Unlock the car and Hazard lights and the both red LED segments turn off and amber shows correctly
Fog light works fine
Reverse light works fine
Absolutely no sign of any dimming/flickering in any circumstance other than when you indicate left or right

Having troubleshooted enough earth faults or poor connections on my own cars over the years, albeit never with LED units I'm not convinced this is the issue.

Looking online I see that you can customise the rear light sequences, so I assume there is some kind of electronic control unit. I did notice when the boot cover was off there was a small white unit on the left hand side, not sure if that's relevant.

Seems a huge co-incidence the car goes for a Service, gets jet-washed and leaves with an electrical issue with rear lights and there is water found around the light units.

Any thoughts?

 

[tracktoy]

Do you have a scan tool, this will tell you the DTC Code for any errors the car is producing that MAY help you identify the issue.

 

[leon_mike]

Unfortunately not. Checking the dealer service sheet the first check shows they checked the rear light cluster and turn signals and this is marked as OK/Completed.

So I think the only option is to take it back to them to fix. It was working OK on the drive to the dealer, it was OK when they checked as part of their inspection. So makes no sense it suddenly broke the minute we drove it home!

 

[nd-photo.nl]

I had an issue earlier with my boot lock, which I traced down to a failed rear window seal. I am currently searching for another leak, as my left inner rear light unit has water ingress. I just picked up the new rear light seals from the dealer, but I dont think its the light seals.

After it has rained, when I open the tailgate completely; water comes spilling out of the top of the spoiler (when its pointing down off course), which does not make sense to me.

It also comes out of the rear light cover in the tailgate identical to your situation My conclusion for now is failed rear window seal

 

[leon_mike]

Found someone with the exact same issue after washing the car posted here:

Rear indicator causes LED DRL on opposite side to flicker

So I just came back from work and drove behind my girlfriend whilst she was driving my Leon facelift with LED lights. I noticed that when she used the indicators, the top part of the DRL that's supposed to go out when you use the blinker would flicker on the other side. The flicker itself is at...

www.seatcupra.net

Low and behold despite torrential rain today, when I got home this evening I checked and lights are working properly again.

Can only conclude that the dealers pressure washing technique breached the seals (which I accept are probably weak but not weak enough to let in rainwater) and resulted in moisture in the lights or a control unit somewhere. Now its dried out its fixed itself.