Disconnecting your car battery is sometimes necessary for maintenance or repairs. However, for 2016 Subaru STI owners, like many modern vehicles, this can lead to a frustrating loss of your car’s personalized settings. From radio presets to crucial engine management data that your STI has learned over time, disconnecting the power source can wipe it all away. This article delves into how you can prevent this memory loss in your 2016 Subaru STI by utilizing the OBD2 port for a temporary power supply, ensuring a smoother maintenance process.
Why Battery Disconnection Resets Your Subaru STI’s Settings
Modern vehicles, including the Subaru STI, rely on constant power to maintain the settings and learned data within various control modules. These modules govern everything from your radio preferences and clock settings to more complex engine and transmission parameters that optimize your car’s performance. When the battery is disconnected, these modules lose their power source, resulting in a reset to default values. This means you’ll have to reprogram your radio stations, reset your clock, and, in some cases, experience a period of less-than-optimal engine performance as your STI relearns its driving conditions.
Utilizing the OBD-II Port: Pin 16 as a Power Source for Your Subaru STI
Fortunately, there’s a way to circumvent this issue in your 2016 Subaru STI. The On-Board Diagnostics II (OBD-II) connector, typically used for reading diagnostic trouble codes, also features a pin that’s constantly powered – pin 16. This pin can be leveraged to provide a temporary 12V power supply to your STI’s electrical system while the battery is disconnected. By connecting a 12V source to this pin, you can effectively maintain power to the crucial modules, preserving your settings and learned data.
Many automotive service centers utilize specialized adapters that connect a 12V power source, such as a jump starter or battery maintainer, to the OBD-II port. This connection is usually fused at 7.5 Amps for safety. This method is applicable to your 2016 Subaru STI and can be a convenient way to avoid memory loss during battery changes or repairs.
The 7.5 Amp Fuse: Understanding the Power Limit and Avoiding Problems
It’s crucial to understand the limitations when using the OBD-II port method. The 7.5 Amp fuse in the circuit is designed to protect the system from overload. While the power draw from the control modules to maintain memory is minimal, activating other electrical components in your Subaru STI can easily exceed this limit.
For instance, simply opening a door and turning on the interior lights can draw several amps. If these lights, or any other accessory, are activated while the car battery is disconnected and power is being supplied through the OBD-II port, the current draw might surpass 7.5 Amps, causing the fuse to blow. If this fuse blows, you will experience the same memory loss as if you had disconnected the battery without any power maintenance. This is a common mistake, even in professional settings, and is often indicated by a reset clock and radio.
Fuse Blown? The Consequences for Your Subaru STI and OBD-II Diagnostics
A blown 7.5 Amp fuse in this context is not related to any Check Engine Light (CEL) issues. It’s a separate circuit designed solely for maintaining memory during battery disconnection. However, a blown fuse will prevent an OBD-II code reader that relies on the car’s power from functioning correctly. If you attempt to diagnose your 2016 Subaru STI using an OBD-II scanner after blowing this fuse, and the scanner isn’t self-powered, it may not be able to establish a connection.
Furthermore, after reconnecting the battery even if the fuse is blown, you might notice some initial rough idling in your 2016 Subaru STI. This is because the Engine Control Module (ECM) needs to “relearn” certain parameters after the memory loss. This rough idling is usually temporary and resolves itself as the ECM adapts.
In Conclusion
Maintaining power to your 2016 Subaru STI’s electrical system via the OBD-II port during battery disconnection is a viable method to preserve important settings and learned data. However, it’s essential to be mindful of the 7.5 Amp fuse limitation and avoid activating any unnecessary electrical loads during this process. By understanding these nuances, you can effectively change your battery or perform repairs without the inconvenience of losing your Subaru STI’s personalized configurations.
