Yellow break light, Master system light, malfunction light, and Hybrid system light on

Your 12v battery needs to be changed. Change that first and see if the car improves. The reading around 9volts will cause all kinds of problems.

The battery at a dealer will be around $200 if you install it yourself, add $100 if they install it

 

Exide Edge, FP-AGM51JIS, $149.95 + $15 shipping (2-5 days)

Exide AGM Car Battery (Group S46B24R)

What I currently have, I like it over the Optima Yellow top.

 

1. Too late now, but if you had known the car would sit for 3 months without being used, it would have been best to disconnect the 12V battery. Running the car once a week, probably for 30 minutes or less, is insufficient. You would have had to leave the car READY for several hours each time.
2. Since the 12V battery is obviously dead, start by replacing that. During the process of replacing the battery, any existing diagnostic trouble codes (DTC) will be erased.
3. Expect that your car has some other problem besides the dead battery, and get ready to spend more money on repairs.
4. If you want to avoid the local Toyota dealer, get Mini VCI so that you can retrieve the DTC to see what is wrong with your car, assuming that problems remain after you've replaced the 12V battery.

Good luck.

 

as a temporary measure, you can try and charge up the 12v to a higher voltage, then see what other problems still occur. It sounds like your HV battery may be having issues as well, and that can cost you $3000+ for new and around $1500 for remanufactured (Dorman)

 

As others have said get a Mini VCI cable, They are less than $25 on Ebay or Amazon. Buying from a US based seller will cost a couple of bucks more but save you a ton of shipping time.

The fan running all the time means your high voltage, traction, hybrid, (the big expensive one) battery is overheating. Overheating is caused by one or more failed battery module.

The cheap solution is to learn how to replace the battery module yourself. The trick is to not kill yourself in the process.

Brad

 

Your problems aren't a result of the traffic stop & the car sitting for 2-3 months. It sounds like your traction battery is failing. If you are in a CARB state the warranty is 10 years/150000 miles. car-part.com shows 2 used batteries in White-Hall, WV. The least expensive one is $650.

 

The car sitting for 2 to 3 months is exactly what killed the traction battery. Or you could call it the last straw that broke the camels back. When battery cells degrade and lose capacity they also develop high rates of self discharge. Daily driving can prop up cells that are self discharging. Take that crutch away and the bad cell discharges to the point of setting off a code. JC91006 managed to get his battery replaced under warranty by letting his car sit unused.

Brad

 

the 12 volt battery is easy to replace. you can get one at an auto parts store, batteries plus store, or online for optima. did your parents transport any pets? it could be that your cooling fan is just dirty. all the best!

 

The thing I don't like about higher mileage Prius cars are the HV battery failures and the oil burning (could be engine problems later) which causes Catalytic Converter failures. And as you move higher up in the mileage department, you are then facing transaxle failures.

Many people think the prius can go 200k - 300k without problems, I think that's a number that's very optimistic. Many will start facing really expensive problems when they get to that high of mileage and you'll have to think really hard before fixing the (expensive) problems.....cause one comes right after another.

I luckily had my HV battery replaced under warranty at 149k but my catalytic converter just gave out at 153k, which is out of warranty. I have another 05 Prius that needed a transaxle at 150k. All are fairly expensive to replace........and all under 200k miles. So think carefully before you start tackling expensive problems at higher mileage, it may just be the start of an expensive venture with the prius.

 

There are lots of tutorials on here that can show you how to repair most parts in the Prius, but you would need to have some general knowledge and tools to do it.

This might be an expensive venture you're heading down, but if you have no other choice, you would just have to take your chances and start repairing the car, one problem at a time.

start with replacing the 12v battery first, then cross your fingers and hope that cures most your problems.

 

if you hit a pothole, maybe it's just a loose connection.