2014 Toyota Prius Three power outlet fuse keeps blowing

To blow a fuse you are drawing to much power or there is a short somewhere (same difference). You could check the resistance of the circuit if you know how to use a meter or perhaps try another charger/cord if you don't want to take it in. The phone itself would cook if it actually pulled 15-20 amps.

 

First, I would investigate the charging requirements of the phone, how many amps are needed? Second, I would examine the entire circuit for that fuse. I would not assume that the circuit with that fuse only contains the power outlet. If that checks out, then I would think the charger/cable might be defective. Can you try another charger/cable?

 

You have to eliminate the iPhone charger as the problem. Can you try a different charger?

 

That is the most ridiculous thing I ever heard. Your car is under full warranty. That's like saying the car doesn't start and the dealer is going to charge you $80 to diagnose it.

Call another dealer. This time, tell them your iPhone doesn't charge. Don't mention fuses or anything else. Let them find the fuse and replace it. When it blows again, let them disagnose the root cause of the problem.

 

This would be my guess. Any USB port should charge the phone, but if there's something wrong with the charger, it could be creating enough resistance to blow the fuse even without a "short."

 

The iPhone charging current is nominally one amp, so I would suspect a defective charger or cable is the culprit.

 

Likely a short-circuit somewhere, either in the supply circuit, or the accessory.

 

Well now that we all have said the same thing over and over...

 

"What I tell you three times is true"

 

Agree totally, don't tell them anything, they'll use it against you.

 

Your car is under warranty. Take it to another Toyota dealer and if you get the same BS write a letter to Toyota Headquarters.

I have a 2014 Avalon. I was using a tire inflator to adjust the pressure in my tires about once a month and it caused a fuse to blow. I stopped using the inflator.

I like the advice that mmmodem gave you. I would do what he suggests.

 

That sort of charger should be releasing some smoke, or at least some hot odor, before it can blow the fuse itself from extended operation.

If the charger is involved, I suspect it is pulling a brief high current surge from a mechanical fault, e.g. wires or plug/socket contacts striking each other momentarily. If the socket is clear of any metallic debris, and nothing appears odd around the plug contacts, then I'd try a different plug-in USB charger.

 

...as an electrical engineer, that sentence bothers me SO much I can't just let it go. Resistance is the opposite of a short. Increase the resistance, and the current goes down.

Have you tried a different cable? Is the outlet free of debris? I agree that the charger/cable/phone can't be taking more than 15A for any great length of time without starting a fire or at least letting out some smoke - that's a fair amount of power for fairly small components. But I think that points to the problem being a much, much higher current for a much shorter period of time. Fuses break after a variable amount of time - the higher you go past the rating, the faster they'll break. One fuse manufacturer specifies that it'll break sometime between 100 hours and never if you exceed the rating by 10% (eg 16.5A on a 15A fuse). That would be dissipating almost 200 watts, which would come out to 71 million Joules over the 100 hours. On the other hand, if you exceed the rating by 500% (90A on a 15A fuse), it will break sometime between 20 ms and 100 ms. That's over 1000 watts, but because the time scale is so much shorter, it's less than 22 Joules of energy. It doesn't take a brain surgeon (or an electrical engineer) to be able to recognize that there's a pretty significant difference between 22 Joules of energy and 71 *million* Joules. 22 Joules is about 5 (not-food) calories - the amount of energy needed to raise the temperature of 5 grams of water (1 teaspoon) by 1°C. That's basically an insignificant temperature change to an insignificant amount of material - unless you happen to see a spark, there probably won't be any heat or smoke to lead you to the problem.

So it's likely a total short somewhere, that's just making a quick spark before the fuse blows, and not doing any noticeable damage. If it's not the charger, cable, or phone, then it's probably one of the wiring harnesses somewhere in the car.

Which brings me to the $80 diagnostic charge; it's totally reasonable for the dealership to bring that up even though the car is under warranty. Many of the things that would cause a fuse to blow will not be covered by the warranty. In addition to the already-mentioned charger/cable/phone defect, the next most likely culprit would probably be a rodent that had chewed on some wires. A manufacturing defect in the wiring harness is certainly a possibility, but probably a fairly remote one. It's way better for them to inform you of the possibility that it won't be covered by warranty up front than to spring it on you after they've found the cause!

One experiment you could run; try not using the power plug at all for anything. If it's the wiring harness shorting to itself, it could still blow the fuse, even with nothing connected. That would be a dead giveaway that it's not a problem with anything you're doing - though it doesn't necessarily mean the warranty will cover it (see also: rodents).

Anyway, good luck. Finding problems that only occur for a few milliseconds every 4 weeks aren't easy. Might be worth the $80, especially if you can get the dealer to agree to not charge you if they declare "no problem found".

 

If it was any sort of mis-wiring, caused by manufacturer, then a minute current drain should show with an open circuit. Checking it might be easier with it out of dash.