Yesterday morning, as I grabbed the keys and got ready to start my Ford F150, I was greeted by the message “Full Accessory Power Active,” and the truck refused to start no matter what. A quick Google search told me this was a shared conundrum among F150 owners.

Whether it’s in the morning or after a short break, it happens out of the blue. Many have tried routine checks and resets, but the issue persists.

Don’t worry, though, in this article, I’ll share the solutions I’ve found to get past this problem.

What Does Full Accessory Power Active Mean in F150?

The “Full Accessory Power Active” code in the F-150 means all electrical accessories will work without starting the engine. So, what accessories are active in Full Accessory Power mode? Ford F150s usually have the following features toggled on in this mode:

  • Interior lights.
  • Radio and media system.
  • Electric windows.
  • Charging power outlets.
  • Climate control features like heating, ventilation, and air conditioning.
  • Gauges and dashboard.
  • Electric door locks.

The availability of these features can vary depending on your specific F150 model.

When to Use F150 Full Accessory Power Active Mode?

Here are some situations where full accessory power mode comes in handy:

  • For quick errands or short stops when you need to use electrical features without starting the engine.
  • While waiting for someone or during a break, to keep the interior comfortable using the climate control system.
  • Enjoying radio, music, or podcasts without running the engine.
  • When you need to charge your devices using the vehicle’s power outlets.
  • To inspect lights, wipers, or other components without starting the engine.
  • In emergencies, allowing access to power for phones or electronic devices.

How To Activate And Deactivate Full Accessory Power Mode In Your F150?

To turn on the accessory mode in your f150:

  • Turn the ignition key to the “off” position.
  • Press the start button again without pressing the brake pedal.

The truck will enter Full Accessory Power Mode, and you will be able to use the accessories I mentioned above, including the radio, USB ports, and power outlets without starting the engine.

You only need to press the start button again to deactivate this mode.

Why Ford F150 Won’t Start While Displaying Full Accessory Power Active?

Here are the reasons why the f150 won’t start while showing Full Accessory Power Active as well as the fixes:

Reasons for Ford F150 Full Accessory Power Active car Won't Start

1. Problem With The Shifter

Your Ford F150’s shifter shifts into “Park” when you open the door, which seems handy.

However, this can cause starting issues. The automatic shift confuses the truck’s system, making it think it’s in “Drive.”

However, the electrical system, including accessories, turns on despite the problem, showing the Full Accessory Power Active code.

How To Fix The Shifter Issue?

  1. Inspect the gear shift mechanism for any visible damage or misalignment. Sometimes, a physical issue with the shifter can confuse the system.
  2. Disconnect the car battery’s negative terminal for 15 minutes, then reconnect it to reset the internal systems.
  3. Examine shifter wiring for damage or loose connections that can disrupt communication.
  4. Ensure the shift interlock solenoid is functioning correctly. If it’s faulty, it might cause issues with the automatic shift.
  5. Check for software updates; they might fix electronic issues in the system.

2. The Inverter System Controller Is Faulty

The Inverter System Controller manages the electrical power in your vehicle, including the starter motor.

If it malfunctions or has communication problems, it can disrupt the power needed to start the engine, causing starting issues.

While it doesn’t solely control accessories, problems with this controller can affect the broader electrical system, including things like lights and the radio, which is why you see the code activated.

How To Solve The Inverter System Controller Issue?

There’s no fix for this. You’ll have to get this serviced at an official dealership. You need to avoid tampering with the ISC. It’s not possible to DIY it.

3. Your Truck Has Weak Battery

The “Full Accessory Power Active” message in your vehicle indicates that the battery-powered system for your truck’s accessories is working fine.

If your truck won’t ignite, it’s probably due to a weak battery or excessive power usage elsewhere.

When starting, the starter motor needs sufficient power. A weak battery may engage the starter but lack the power to turn the engine, causing a rapid clicking sound.

What Steps Can You Take To Fix Weak Battery?

  1. Mix one tablespoon of baking soda with one pint of water.
  2. Rinse terminals with the baking soda solution. Scrub them with an old toothbrush to remove corrosion.
  3. Loosen and remove the negative terminal first, then the positive terminal.
  4. Check for wear and corrosion. Replace damaged parts if necessary.
  5. Use a battery brush to clean the inside terminals until shiny. Clean posts by rotating the brush on them.
  6. Pour baking soda solution on the battery, wipe it, and dry it with a towel.
  7. Attach the positive terminal first, then the negative one.
After cleaning, apply dielectric grease or petroleum jelly to terminals to prevent corrosion. Check for corrosion periodically and clean terminals as needed to ensure a strong connection.


Does accessory mode drain the battery?

Yes, using accessory mode gradually uses up your truck’s battery power.

Does the accessory mode use gas?

No, accessory mode doesn’t consume gas; it relies on the truck’s battery.

How long can the F-150 be in accessory mode before it dies?

The F-150 can usually be in accessory mode for about 30 minutes before the system automatically turns off to prevent the battery from completely draining. That might change based on what features get turned on with your specific model.


The Full Accessory Power Active code isn’t something to worry about, it’s your ticket to enjoy a moment in your truck without draining its resources.

But if your F150 doesn’t start while displaying “Full Accessory Power Active” you now know exactly what to do. So go on and try these fixes.

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