A while back, 2018 to be exact, in response to threads like this, I searched the Internet for the correct bulb for a Tesla Model S and bought some high quality D3S HID bulbs for my 2014 Model S hoping that if I fitted them it may improve the lighting performance. Life was busier then and I promptly put them in the cupboard And forgot about them.
Last Sunday a message kept popping up in the car saying that the RH headlight failure has been detected and to contact service.
It‘s currently an intermittent fault so I found the box in the cupboard and found the D3S globes and had a go at changing the globe yesterday and today. After many hours of work, a complete disassembly of the front of the car the original globe is back in the right hand headlight and the car is back together, still broken.
What went wrong?
As eluded to previously in this thread, when the Model S was going through Australian Design Regulations (ADR) Tesla was forced to lower the globe wattage of the HID headlights from 35W to 25W making Australian Model S unique in the world where they are fitted with a D8S 25W HId globe whilst the rest of the world Model S are fitted with D3S 35W HID globes. If I recall correctly the change was made as apparently ADRs require headlamp washers for a 35W HID system so that dirty HID headlights don’t blind oncoming traffic and Model S has no headlight washing equipment.
In my journey over the last few days I discovered that to reduce the wattage to 25W it’s necessary to change the globe to a D8S 25W globe which is physically identical to to a D3S 35W globe except for the lower wattage and importantly the seating ring that contacts the headlight socket is keyed differently. As a result the D3S will not sit correctly against the headlight socket and you cannot twist the locking ring to lock the bulb to the headlight.
Unfortunatly for me I only noticed the difference after I disassembled the entire front of the car and removed the headlight so I could see the mating surface and spotted the difference of key way on the globe mating surface.
It was only then, I checked the mating ring of the original globe and read the label to discover the difference.
Examining the headlights I note that mine have lots of wax crayon marks on them suggesting that were disassembled in the factory to change the central lens structure to accept the lower wattage D8S globe. If my theory is correct, it explains why you can look up on the internet the correct globe for a 2014 - 2016 Model S with HID headlights and you will be told it’s a D3S but for Australian and I assume New Zealand Model S the correct globe is a D8S and is a much rarer and difficult to source globe.
Moral of the story, don’t believe everything you read on the internet or you will end up wasting a day and a half getting nowhere Like me.
