Umm... how did the dome light fuse blow??

Have your friend pick up a new fuse and replace it. I am sure that sounds like your issue?? Maybe all the doors and lights on just happened to blow the fuse for whatever reason...10 mins...not the general time to have all doors and hatch open etc...but a fuse is small price if that's all it is....

 

Perhaps you had a questionable fuse. Keep a spare just in case.

Tom

 

Often fuses will blow from old age - especially if they are used heavily. A fuse is a piece of metal designed to melt when the current drawn through them exceeds a certain level for a period of time. For example, if you draw 100 amps through a 10 amp fuse it will immediately blow. If you draw 12 amps through a 10 amp fuse, it will blow after a few minutes. If you draw 10 amps through a 10 amp fuse it will blow after quite a period of time. Get the idea?

Your dome fuse was likely used near its rated limit over a period of time and just gave up the ghost due to its age. This does not mean you have an electrical problem, just a tired fuse.

 

Manufacturing tolerances being what they are, once in a while you just get a bad fuse, you replace it, and the new one never blows.
All cars that I have had that were made in the last several years have spare fuses in the fuse block along with a fuse puller, doesn't the Prius?

 

Oddly though, at least two other owners have reported fuses blowing for no obvious reason. Same symptom, the slip indicator coming on.
hmmm

 

It could be that this circuit runs close to the edge when all of the interior lighting is in operation.

Tom

 

Glad i saw this thread. It never would have occurred to me that something as simple as a dome light fuse would disable a car -- ANY car! I'll make sure I locate it, replace with new, AND carry a spare. What a bummer it would be to be out and about, and without a spare when it failed, huh?

 

Interesting. There have been some comments below, but I'll try and give a bit more definitive answer. I think I can do this because, well, I happen to design fuses into electronic equipment from time to time.

First things first: Fuses have lifetimes, much like light bulbs, and for pretty much the same reason: Metal fatigue. For a fuse to work it has to warm up to the point of melting when you hit its over current specification. Now, suppose that your "normal" load is 1A. Typically, a 10A fuse would be used in this case. The idea is that if there's a short, there'd likely be 10X the current and said fuse would blow. But, if a 100A fuse was used instead, a fault typically wouldn't go up to 100A, the fuse wouldn't blow, the spot where the short was would get hot, and Fires Would Be Us.

Given that metal is metal, if a strip of metal is carrying 1/10 the current necessary to melt the thing, said metal will get warm. That means that every time the current is turned on and off the metal will flex while it expands and contracts; hence, over time, all fuses will tend to blow. That goes for circuit breakers, too.

The other interesting thing about the math is that the smaller the fuse, the hotter it runs at that 0.1X current point. A 10A fuse running at 1A runs at a certain temperature; a 0.1A fuse running at 0.01 A runs much hotter that that 10A fuse running at 1A. Therefore, smaller fuses tend to last a shorter period of time. I suppose that the 0.1A fuse, being thinner, is naturally more flexible than a thicker, stiffer 10A fuse, so maybe it's not quite as direct, but there you are.

So, in no particular order:

1. Just like if one tests the lifetime of a case of 100W light bulbs, one quickly finds out that the (say) 2000 hour time for the light bulbs is an average. There will be some short-timers in there.
2. Raising the current draw on a fuse makes it run hotter. The heat-current relationship is not linear, so doubling the current, while still being less than the limit for said fuse, is going to make that fuse last a lot shorter.
3. Early death in fuses is a given, just like in any electronic device. Look up the phrase, "Bathtub Reliability Curve." Some things die just out of the box: It's the reason that car manufacturers have warranties.

Regards,

KBeck.

 

Fascinating. I was in Electronics for years and now I understand the stern warning on overfusing. 10X Wow!