iPhone 12/13 Series True Tone Transfer
Ever since the iPhone 12 came along, and continuing with the 13 series, the True Tone setting has been controversial. Screen replacement and successfully restoring this function has been troublesome, and not many understand how this feature works from a technical perspective. I will describe it in understandable terms and address what I've done at CDC to deal with the problem.
What Is True Tone?
In simple terms, it is a setting that softens the whites in your display and works in concert with the auto brightness/dimming to adjust the tint as the display brightness changes. When turned on, it adjusts the display, so colors remain consistent at different brightness levels. It's a very nice function that gives your display a crisper and more pleasing appearance. For your reference, it is located in Setting>Display and Brightness.
What Are The Problems With True Tone?
True Tone is an often-overlooked step in the repair process. Since its implementation, I have only seen exactly one instance where a previously repaired device came into this shop with it properly functioning. All other instances it was malfunctioning. Why is this so?
Ever since the iPhone 8, True Tone has been a standard feature in the iPhone. Unfortunately, what a lot of 3rd party repair shops do not understand is that it requires special programming to maintain functionality. Simply put, when you break your screen, the repair person must use replacement displays that have chipsets capable of being flashed and it must be flashed, it's that simple. But what does that mean exactly?
The original, or "native", display has a chip on the back of it that is programmed with a code sometimes called "MtSN", and this code is what turns on the True Tone feature. You must use a special tool that reads that code and flashes it to the chip on the replacement screen. If you do not do this, the True Tone function magically disappears, and the display will appear too bright. I cannot tell you how many times I find phones in this state when they come in this shop. Too many to list.
Other Factors That Affect True Tone Functionality
True Tone is not just affected by lack of flashing. It is also dependent on matched components in order to work properly. The iPhone 8, being the first iPhone with the feature, had a front camera that was matched to the CPU. Change out the front camera? Bye bye True Tone. Fortunately, there is a workaround provided you can microsolder. The proximity/brightness sensors on the camera flex are the matched components. If you hot air off those sensors and solder to a new camera flex, you're good to go. Unfortunately, few techs understand this and far too often I've found phones in this state and there is nothing I can do to fix it.
These matched components have been a factor since the 8 and it has gotten even more complicated on the Face ID equipped iPhones. Repairing damaged components is increasingly more challenging with each model year, so it is imperative that whoever does your repair is gentile and properly moves components from one display to another without damaging them. Otherwise, you're forced to go to Apple and pay much more, and in many cases, they won't touch it if it's been hacked up.
iPhone 12/13 True Tone Complications
Starting with the iPhone 12, the True Tone transfer became far more complicated. First, the iPhone 8-11 series had a less restrictive system for retaining the function. For example, I mentioned phones coming to this shop without True Tone. OK, no problem on an 8-11. My flashing tool includes software that can read the "MtSN" code from the CPU and recreate it. Write to the new display and True Tone is alive again provided no mismatched components are onboard.
That all changed with the iPhone 12. Apple sort of took True Tone "in-house", requiring a link to their proprietary system called "GSX". Unless you're the Apple store or one of their agents, "GSX" is not available to 3rd party shops. So, replacement of displays for some time at my level made True Tone a lost cause. This was a real problem because we already have tons of shops that are clueless about the function as it is. Adding a further layer to the process made it even worse. If you had your screen replaced by a 3rd party shop, you not only lost True Tone, but you also couldn't get it back because the software cannot read it from the phone. Apple closed that loophole.
Resolutions To The Problem
Fortunately, the problem has been resolved, however with an important caveat. I can retain True Tone now, as tools have been developed to properly flash the new display. But there's a catch...the "native" screen. I cannot retrieve the "MtSN" code from the phone; only from the original (native) display. If you crack your screen, watch out! It must be flashed by extracting the code from the original display. If you had it replaced elsewhere, I'm sorry but there's no recourse. True Tone is lost for good.
Yes, I can retain True Tone on your 12 or 13 provided it has the native display installed. But one thing I cannot do is eliminate the warning message. Starting with the iPhone XS series, Apple started partially serializing batteries, and with the 11 they serialized the display. Simply put, they have additionally programming written to the displays and batteries to that the phone can tell if it's been changed. You'll get a pop-up message that says, "Unable to Verify That Display/Battery Is Genuine". This warning message eventually fades into settings, but it will always be present.
How can this be prevented? With batteries it's possible but a real pain. You have to rebuild the battery by hand using the circuit board from the native battery, spot-weld it to a new battery, then reset all the parameters. With the 11 series and up? You need an additional plug-in module to allow the phone to recognize the battery as genuine. With displays it's even worse. You have to somehow transfer a chip from the native display to the new one, which is a VERY complicated process and quite frankly not realistic. There are some new tools coming out that make the process more realistic, but they're expensive and would make the repairs far too pricey to be worth the trouble. My opinion is yes on battery but live with the message on displays.
The manufacturers continue to push the envelope on repair complications. The reasons are numerous, and I'd rather not get into the politics of it all. I find that the old adage "if you don't have anything nice to say, don't say anything at all" serves me well at CDC. What I can assure you though is that I'll always study hard and be aware of all of these complications with every new device that comes out. Apple isn't the only company that does this, that much I can assure you, but they're one of the most aggressive in doing so. All I can do is work the problem and come up with solutions that are acceptable. The key takeaway all of you should have from this is that 3rd party shops are the Wild West when it comes to repair. Shops like CDC, who stay up to date, are one thing. But far too many have no idea what's going on and it affects the quality of your repairs.