Ford “Full Accessory Power Active” Car Won’t Start Fixed 99%

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full accessory power active car won't start

In general “Full Accessory Power Active” warning light on a Ford vehicle is not a fault code. But the fact is, sometimes it can appear and the car won’t start if any faulty component or glitch is found. Don’t get confused. It’s going to be easy.

What Does Full Accessory Power Active Mean?

The “Full Accessory Power Active” message on a Ford vehicle essentially means that the car’s electrical system is providing power to all the non-engine related components, like the radio, lights, and interior features, without the engine running.

While accessories are powered, the battery isn’t being recharged by the engine running. So, if you leave the car in this condition for a longer time, eventually it is going to drain the battery. As a result, the car won’t start.

The message should disappear once you start the engine, as all systems then switch to engine-powered electricity. But sometimes your car won’t start with this warning light when something is causing the issue.

How to Turn Off “Full Accessory Power Active”

Fixing the “Full Accessory Power Active” dashboard warning depends on the actual causes. If it is a software glitch then the solution is quite simple.

If it is related to any component then the solution is going to be tougher based on the faulty component. I will talk about the easy solution first.

Solution 1. Fix the Software Glitch

I’ve personally experienced a glitch in-car software. Before, with traditional keys, you could smoothly go from accessory mode to starting the car.

But with newer push-button starts, it gets tricky. You can’t just press the brake and start from the accessory mode; you have to turn off the accessory first.

If your car is having trouble starting, try this sequence:

  1. Allow your car to sit for a moment (around an hour recommended).
  2. Turn off the accessory by pressing the Start button without touching the brakes.
  3. Then, press the brakes and hit the Start button again.

It’s a simple workaround, but it’s a software design problem that makes it less intuitive than it should be.

Solution 2. Check for the Battery

If the above trick did not solve the issue then it’s time to check the components.

Start by checking the battery’s voltage; it should read around 12.6 volts for a fully charged battery. Most of the time weak battery causes various dashboard warnings. You can try jump-starting the vehicle to confirm.

Even with a seemingly good voltage, perform a load test. If the battery drops below 8 volts during the test, it indicates a faulty battery.

Change the battery if it’s too old or weak. If that’s not the case then make sure the battery terminals are clean and tight enough.

Along with the battery, I suggest you check your key fob. For keyless systems, a weak or dead battery in the key fob can cause detection issues. Test with a spare key fob to identify the problem.

Solution 3. Check for Clogged or Stuck Purge Valve

Sometimes, the “Full Accessory Power Active” warning light can come on due to a blocked or stuck purge valve.

This part can block the airflow into the gas tank, triggering the warning. You might notice this issue occurring after some time when pressure builds up.

If you face this problem, check the gas tank for signs of compression, as it might be highly compressed, and nearly cracking.

The blocked or stuck purge valve should be cleaned properly and make sure there’s smooth airflow into the gas tank.

Solution 4. Try Shifter Adjustment

Well, If you still come across the “Full Accessory Power Active” warning in your Ford vehicle, a possible solution involves addressing the shifter behavior.

If the warning occurs when the door opens, and the shifter goes into park automatically (instead of being manually placed there), follow these steps for a possible resolution:

  1. Lower the Shifter:
    • If the automatic park feature triggers the warning, try lowering the shifter.
  2. Raise the Shifter Back Up:
    • After lowering the shifter, raise it back up.

Warning should be gone with this method. but If the warning persists, turn off your vehicle, wait a minute or two, and then restart it.

Solution 5. Check for Damaged Relays

Sometimes, Relays on the fuse box can trigger this “Full Accessory Power Active” warning light.

Over time, these relays may succumb to corrosion, often indicated by a greenish tint, especially if your car remains parked for extended periods.

This corrosion can result in false signals activating the starter and triggering the warning light.

So, focus on the relays in the fuse box, situated on the driver’s side in the engine bay.

The good news is that this problem is not only solvable but also cost-effective.

I advise you to replace all seven relays to fix it. This can be a straightforward task that you can tackle yourself. Begin by carefully pulling out the old, potentially corroded relays, and then insert the new ones into their place.

Solution 6. Check the Brake Pedal Switch

We have talked about the battery issue earlier. But battery drain especially due to a faulty brake pedal switch could also be a reason for the “Full Accessory Power Active” warning in your Ford vehicle. Though this is not common.

The faulty switch in the brake pedal assembly causes two issues.

  1. The car fails to recognize the compression of the brake pedal before hitting the start button.
  2. The brake lights remain illuminated, leading to a gradual battery drain.

When this happens and during attempting to start, you may hear clicking, and clattering, and witness various dashboard notifications, seemingly without a clear explanation.

If facing these symptoms, a temporary fix involves jump-starting the vehicle using a portable jumper box.

Find a dealer or well-known mechanic to replace the malfunctioning brake pedal switch to fix the core cause of the problem.

I hope you fix your warning light asap. I can assure you that the solution mentioned in this article will mostly solve the issue.

Comment below and share your experience with this “Full Accessory Power Active” warning. What was the cause and how did you fix it?

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