When you need to disconnect your car battery in your 2012 WRX, you might not realize that doing so can lead to more than just a quiet engine. Modern vehicles, including the 2012 WRX, rely on constant power to maintain settings in various control modules. This “learned” data is crucial for optimal vehicle performance. Disconnecting the battery can erase this data, alongside simpler settings like your radio presets and clock.
In some vehicles, the accessory power outlet remains live even when the ignition is off, offering a potential workaround. By connecting a 12V power supply to this outlet, you could theoretically maintain power to the system while changing the battery. However, Subaru vehicles, including the 2012 WRX, typically do not have constantly powered accessory outlets. This means we need to find an alternative power source to prevent memory loss during battery disconnection in your 2012 WRX.
One effective solution lies in the OBD2 port of your 2012 WRX. Pin 16 of this port is designed to be always powered, providing a direct connection to the car’s electrical system. This constant power supply makes the OBD2 port an ideal location to introduce temporary power while the main battery is disconnected.
Many automotive service centers utilize specialized adapters to connect a 12V power source, such as a portable jump starter, directly through the OBD connector. This method, when used correctly with a 7.5 Amp fuse, can successfully maintain power to the vehicle’s essential systems, preserving your settings during a battery change.
It’s crucial to remember that while using the OBD2 port to maintain power, you should ensure all vehicle accessories are turned off. The modules and systems requiring power to retain memory draw minimal current, well within the 7.5 Amp fuse rating. However, activating power-hungry accessories like interior lights (simply by opening a door) can significantly increase the current draw.
If the current drawn by these accessories exceeds the 7.5 Amp fuse limit while the car battery is disconnected and power is supplied through the 2012 Wrx Obd2 Port, the fuse will blow. This effectively interrupts the power supply, leading to the same result as disconnecting the battery without any power maintenance – loss of presets and learned data.
This situation is a common, often unintentional, occurrence. Drivers usually notice it when their clock and radio are reset. In some cases, a 2012 WRX might experience rough idling for a short period after battery reconnection until the Engine Control Module (ECM) “relearns” the necessary parameters for smooth operation.
It’s plausible that if you recently had your 2012 WRX battery replaced and experienced memory loss, the technician might have attempted to maintain power via the OBD2 port but inadvertently triggered an accessory, causing the fuse to blow.
It’s important to note that this 7.5 Amp fuse, associated with maintaining power through the OBD2 port, is unrelated to Check Engine Light (CEL) issues. A blown fuse will not cause a CEL. However, if this fuse is blown, it will prevent a code reader that relies on the car’s power from operating when connected to the OBD2 port. Therefore, if you are trying to diagnose your 2012 WRX using an OBD2 scanner and it’s not powering on, checking this fuse would be a worthwhile step.
In conclusion, utilizing the OBD2 port on your 2012 WRX (specifically pin 16) is a viable method for maintaining vehicle memory during battery disconnection. By using a 12V power supply and a fused adapter connected to the OBD2 port, you can avoid losing important settings. However, being mindful of power draw and avoiding the activation of vehicle accessories during this process is crucial to prevent blowing the fuse and defeating the purpose of memory preservation.
