VSC warning light

Hmmmm. A four year old car with 25K miles means that the car isn't driven that much. The blown fuse issue I can't speak to but it kind of meshes with my next comment. I'd say your 12V battery is toast. Can you give us an idea regarding how much this car is driven (days per week, hours per day and approximate times in between when the car is parked and started again)?

My opinion may vary from others but charging at 13.7V puts the Prius at an automatic disadvantage from the start. Couple that with a small battery (albeit sized correctly because there are no starter motors) and you have the making of a short life span.

You may have two issues, which was caused by one single issue. The first thing I'd do is disconnect the -12V chassis ground wire that connects the body frame and 12V battery. If you have one, put a Fluke type DMM (even a Radio Shack el cheapo would be fine for this experiment) in series from the battery cable to chassis frame and measure the current. I've never done it but I think it should be no more than 60mA (someone correct me if my number is incorrect).

If it's more or excessive, something is either on or defective and drawing unnecessary current. If the mA reading is correct, I'd just replace the 12V battery since you're about due anyway (if you haven't already). As for the blown fuse, on-vehicle measurements would need to be taken.

 

No problem. In general, batteries (especially ones that aren't deep cycle) don't fare well, in terms of longevity, when they are depleted and stay that way for a long period of time. Adding on to this issue is your limited driving cycle, which doesn't really do the job when it comes to fully charging the 12V battery.

In laymans terms, I think your 12V battery was dying a slow death. Most people see their batteries go bad around five years, so the fact that you got four out of it is pretty good given the fact that you don't drive it so much. Regardless of what the outcome is, I'd push them to replace your 12V battery since it's still under warranty because it needs to be replaced anyway.

 

If I correctly understand the OP, a fuse has been replaced twice. You might ask what is the exact name of that fuse, and post. Apparently the vehicle has a wiring problem.

It is certainly possible that the 12V battery needs to be replaced but a weak battery would not cause a fuse to blow.

 

Only if it were connected to an inductive load, such as a fan motor. With such loads, low voltage can produce high current.

However, that seems unlikely in this case. I agree with Patrick that the problem is not likely the battery, but some other wiring issue.

Tom

 

His battery is probably bad and he has some other issue going on as well as indicated in my first post. The excessive current (if below the rating of the fuse) over a period of time may have caused the battery to fail prematurely. Four years is getting to the median of battery longevity and it should be replaced regardless.

The dealership telling you that an "overhead" fuse blew is vague and doesn't even make any sense because there is no overhead fuse. However, the overhead equipment (smart key, courtesy lights, radio) are on the dome fuse, which is probably the one that blew.

FWIW, years ago (recalling from memory here) I had a Chevy Tahoe that was giving me issues. Slowly over time it would have trouble starting. Finally when the weather turned cold it just wouldn't start at all. I went and got a new battery and she same sh*t kept happening a week later. I yanked off the battery cable and the truck was pulling 500mA with nothing on. I started pulling fuses one-by-one and when I pulled the radio fuse the current dropped significantly.

I took the radio out and when I disconnected the ACC line from the radio, the current dropped. I ended up putting in a relay that would activate when the ignition was on. I would lose my preset stations and the clock but I didn't care because I had an add-on Sirius receiver.

My point is, there are two issues and one of them is a failing battery.

 

Sound advice. Something is causing the battery to fail. Find that and you most likely have the problem. Start with the dome light circuit.

Tom

 

Do you have any friends that can help out. The things we are speaking about here are not complex at all and most people who have done oil changes/replaced light bulbs can most likely do these checks.

 

Being a female isn't exactly the issue here. There are dozens of female engineers in my office who'd be more than happy to back me up on this... Good on you for looking after the car yourself!

 

If the VSC light is on for more than a momentary period associated with your tires slipping while you are driving, then a diagnostic trouble code should have been logged by the skid control ECU.

 

Hi Lisa,

Now that the car has been returned to you, and considering that you don't drive very much, I suggest that you start by purchasing a battery charger. At least once a month, hook up the charger overnight to charge the 12V battery, using a 4A rate of charge or less. (The battery has a warning sticker about not charging at a faster rate than 4A.)

You can either connect the charger at the main relay/fuse box near the inverter; or else connect it directly to the battery at the right-rear hatch floor corner. Please do a search as there are numerous posts regarding how to do this.

A search will also reveal to you a "hidden screen" on the MFD which allows you to assess battery voltage. However this is only accurate to +/- 0.5V so the readings are subject to some error.

 

I had this very same issue. The factory service tech found that a cable from engine compartment running us the A pillar was stretched to tight and causing a connector to short. Maybe you have the same problem. I took more that two days to correct problem. Luckily I got a loaner from the dealership. Good luck

 

Hi Lisa,

When you are evaluating a battery, there are two characteristics of interest:

1. The battery's state-of-charge, which can be estimated by measuring open-circuit voltage after the battery has been left undisturbed overnight (to allow surface charge to dissipate)

2. The power available from the battery, typically measured in A-h (ampere-hours)

1 is measured using a voltmeter. An approximate voltage can be determined via the MFD secret screen, as previously suggested. A new absorbed glass mat 12V battery, fully-charged, will measure 12.9V. Typically, a battery in good condition and reasonable charge will measure ~12.6V. If you measure 12.2V or lower then the battery is seriously discharged.

2 is not easy to measure without specialized test equipment that will provide a load on the battery to assess available power. The point of my mentioning 2 is that it is possible that your battery will measure a relatively high voltage, yet still be near end-of-life as it has limited power storage and delivery capability.

If your battery is original equipment then it is 4-5 years old. Especially in areas with cold winters, that is about what you can expect in terms of service life. If you desire to maximize its remaining life then it would be good to keep the battery fully-charged. And in the future, after you replace the battery, if you continue to log relatively few miles on the car, it would be good to periodically connect the battery charger to keep the new battery in optimum condition.

 

Intermittent electrical faults are notorious for frustrating even the best technicians. This sort of thing can be set off by going over a bump, for instance. Having chased some phantoms over the years, I would hope that they can find something along this line. But do carry a stash of spare fuses with you, just in case.