Have you ever turned off your vehicle, only to see a message on your dashboard saying, “Full Accessory Power Active”? If so, you’re not alone. Many car owners experience this issue and wonder if it will drain their battery or indicate a bigger problem. This warning means that certain electrical components remain powered even after turning off the ignition.
In this guide, we’ll break down:
- What Full Accessory Power Active means
- Why it happens
- Possible risks and battery drain concerns
- How to troubleshoot and fix the issue
By the end, you’ll have a clear understanding of this feature and the best steps to take to keep your vehicle running smoothly.
What Does “Full Accessory Power Active” Mean?
Modern vehicles come with multiple electronic components that remain functional even when the engine is off. Full Accessory Power Active is a state where the car keeps power running to accessories like the radio, infotainment system, power windows, or climate control. Typically, this mode is designed to last for a short period or until the driver exits the car.
Key points:
- Allows continued use of accessories without running the engine.
- Common in Ford, GM, Honda, and other modern vehicles.
- Normally shuts off when you open the driver’s door or after a set time.
If the system doesn’t shut off properly, it may indicate a deeper issue requiring attention.
Common Causes of “Full Accessory Power Active”
1. Faulty Door Sensors
Many vehicles rely on door sensors to deactivate accessory power when you exit the car. If a sensor is faulty, the system may not register that the door has been opened, keeping accessory power on.
Signs of a faulty door sensor:
- Dome light doesn’t turn on when opening the door.
- Door ajar warning stays on.
- The car doesn’t lock when using the key fob.
2. Ignition Switch Malfunction
Your ignition switch is responsible for turning power on and off in different modes. If it fails or sticks, it may not properly transition out of accessory mode.
Symptoms:
- Difficulty turning the key or pressing the start/stop button.
- Accessories stay on even after shutting off the vehicle.
3. Software or Electronic Glitches
Some newer vehicles experience software issues that prevent systems from shutting down properly. This can often be fixed with a reset or software update from the manufacturer.
4. Low Battery Voltage
A weak or failing car battery can cause electronic malfunctions, including improper power states.
Warning signs of a weak battery:
- Dim headlights or interior lights.
- Clicking noise when turning the key.
- Slow engine cranking.
5. Defective Relays or Fuses
Relays and fuses control the power flow to different systems. A stuck relay could keep power running longer than needed.
How to Fix “Full Accessory Power Active”
Step 1: Open and Close the Driver’s Door
Sometimes, simply opening and closing the driver’s door can reset the system. Try this first before moving to advanced fixes.
Step 2: Restart the Vehicle
Turn the car back on, wait a few seconds, and then turn it off again. This might help reset any temporary glitches.
Step 3: Check the Door Sensors
- Inspect if the dome light turns on when you open the door.
- Clean the door latch area and sensors with electrical contact cleaner.
- If problems persist, replace the door sensor.
Step 4: Check Battery Voltage
- Use a multimeter to check if the battery reads 12.6V or higher (when off).
- If below 12V, consider replacing the battery.
Step 5: Inspect Ignition Switch
- Wiggle the key or push the start button multiple times to see if it responds.
- If accessories stay on, the ignition switch may need replacement.
Step 6: Perform a Hard Reset
- Disconnect the negative battery terminal for 10 minutes.
- Reconnect and restart the vehicle.
- This can clear minor software glitches.
Step 7: Scan for Diagnostic Trouble Codes (DTCs)
Using an OBD-II scanner, check for error codes that may indicate electrical issues requiring professional attention.
Step 8: Update Software or Visit a Mechanic
If none of the above steps work, contact your dealer for a software update or diagnostic service.
Preventing Future “Full Accessory Power Active” Issues
✔️ Regular Battery Maintenance
- Test your battery every 6-12 months.
- Replace it every 3-5 years to prevent electronic malfunctions.
✔️ Keep Your Ignition System in Good Shape
- Avoid excessive use of push-start without starting the engine.
- If you notice difficulty turning the key, get the ignition switch inspected.
✔️ Update Your Vehicle’s Software
- Check for software updates at your dealership to prevent electrical glitches.
✔️ Inspect and Clean Door Sensors Regularly
- Remove dirt and debris from the door latch area.
- If you experience door-related issues, replace the sensor promptly.
Conclusion
The “Full Accessory Power Active” message is often harmless but can indicate potential electrical or battery issues if it persists. The best approach is to start with simple fixes like checking the door sensors, restarting the vehicle, or resetting the battery. If the problem continues, deeper diagnostics such as an OBD-II scan or ignition system inspection may be required.
By following these troubleshooting steps and preventive measures, you can keep your car’s accessory power system functioning properly and avoid unnecessary battery drain. If in doubt, a visit to a trusted mechanic or dealership can provide professional insights and solutions.
