Service Mode is a weird function that doesn’t have a counterpart on the Android Suica•PASMO side. The JR East Apple Pay Suica help page used to mention this. The iPhone Service Mode explanation says, “Service Mode will allow station agents and kiosks to help with any issues with your card.” The street reality is that station agents don’t need you to put the device in Service Mode, just fork it over and they can fix any Suica•PASMO issue for you.
This difference exists because Osaifu Keitai smartphones (and the candy wrapper Google Pay Suica) have a dedicated FeliCa chip. Apple created it’s own custom FeliCa implementation hosted on the iPhone A Series and Apple Watch S Series SOC. But the Apple implementation did not really mature until A12 Bionic and the Express Card (Student ID)/Express Transit cards with power reserve feature. The A12 Bionic Secure Enclave and Secure Element directly support limited NFC transactions that bypass iOS. It’s the same way a dedicated FeliCa chip works on Android.
This means that Apple Pay Suica•PASMO on pre-A12 devices requires iOS/watchOS to be up and running for Suica and PASMO to work. Unfortunately this also means that different iOS versions sometimes have performance issues on pre-A12 devices and that iOS occasionally drops the ball. iOS 12 for example was very buggy for many Suica users, fortunately iOS 12.3 fixes all issues with great Apple Pay Suica Express Transit performance.
The Dead Suica Notifications/No Suica Balance Update problem happens occasionally and the way to fix it is to turn on Service Mode and leave it until it turns off automatically in 60 seconds or the screen goes dark, whichever comes first. Here’s the relevant section from Apple Support Using Suica or PASMO on iPhone or Apple Watch:
If your Suica or PASMO card balance doesn’t update
- Open the Wallet app on your iPhone.
- Tap your Suica or PASMO transit card, then tap the more button .
- Turn on Service Mode, then authenticate with Face ID, Touch ID, or your passcode.
To turn off Service Mode, tap on the card. If your balance is still incorrect, restart your iPhone.
Service Mode syncs and reconciles iOS with the Suica•PASMO Stored Fare (SF) balance information from the embedded Secure Element implemented inside the A Series/S Series.
Service Mode seems pretty useless on A12 and later Bionic devices, a restart works best, but it’s still useful for Apple Watch which does not have the A Series Bionic power reserve feature. I imagine Service Mode on iPhone is more for show than actual functionality, although Service Mode is useful for cash recharge on 7-Eleven ATM machines where you have to put the device upside down to capture the ATM NFC antenna hit area.