Prius won't start...ready sign never turns on

Most common issue would be the 12v battery. If the brake switch is bad, it would generate a DTC and your dealer would be able to scan for it. I'd recommend checking all your connections on the 12v and make sure it's charged up and in good health. Also check your battery on your key fob. If that battery is low, I would think that can cause your problem too.

There is no definitive fix to your problem as nobody is sure what the problem is.....

 

I just don't understand how a dealer can't fix that issue...this car throws DTC for everything and stores it...and we are talking about a big problem which won't start the car not tire pressure or interior light malfunction.... I would assume that is a hybrid issue not a 12vbattery one...I've had dead battery that shows charge of 10v in one of my Priuses it tried to start but everything was flashing like a disco club... So that's why I think it is not related tonthe 12v battery...it is something bigger and there should be DTC.

 

What is a DTC ? Thats a new term for me.

 

Diagnostic Trouble Code

 

Thanks for the help and the info. I will be taking our Prius in for the regular routine service soon and I will use this knowledge when I speak to the service adviser.

 

Do you STILL not have your problem fixed ??

Just like anything else, the 12 V battery can be intermittent.......and there is a low voltage threshold where some or all of the computers in the car won't boot up right.
Then when you shut it off, the battery will sometimes work a little bit better a half hour or more later.

This condition often shows up when the battery is more than 4 years old with "normal" use OR with a much younger battery in a car that gets very light use. Sometimes it is suspected that cars sit on the dealers lot with a dead battery for months before sale; certain to reduce it's life dramatically.

The whole situation has been discussed in a TON of threads on here already.

And yes, a LOT of owners have reported "definitive fixes" for this kind of problem. Sometimes obvious things like brake switches are found but more often everything else is logically eliminated and a new battery fixes it.

Alas, some dealers don't buy into that if a warranty replacement is involved.
The "mechanics" are trained to chase each DTC individually or by type and have no idea what to do it multiple codes across various systems show up all at the same time.
Answer: Look for something common to all the systems that appear to be failing: The 12 V electrical system. Weak point: the battery.

 

Thanks ! I really appreciate the insight and info I've obtained from the members of this forum. The reason this has dragged on in our case is that we drive our car maybe twice a week. We live in a small town and bicycle or walk for most of our errands and commuting. So, even though the problem is in the back of our minds it really rears it's ugly head only sporadically. It has never failed to self correct so far given a little patience.

 

It will fail completely one of these days......and Mr. Murphy says it will be at the most inconvenient time.

Your usage (or non-usage) is a perfect example of the driving pattern(s) that put a strain on the battery.
This has been discussed in MANY threads on here already.

At this point, I think you need a new battery AND more importantly, you need a small automatic battery charger OR you need to change your driving habits to get in at least 30 miles once a week, all at one time. Not only will that be good for the battery and the engine, it will ensure that you need to put gas in the tank every 6 weeks or so, helping keep the gas fresh too.

Connecting the small charger once a week overnight should keep the battery healthy for a long time but it won't help the oil circulate or keep the gas fresh.

The phantom electrical problems have given you an early warning that driving a car too LITTLE can be worse for it than driving too much.
Please heed the warning, for your own convenience and safety.

 

jaymac, our usage is similar: we're driving maybe twice a week. Sometimes more like 6~7 days between startups. Try to consolidate chores into that trip, and make an extended drive at least once a week. Also, I monitor the battery with a digital multi-meter, and occasionally hook up a smart charger. Last time charging, I took the battery right out of the car, cleaned clamps and posts, and did the charging at room temp in the house. Seemed to help, is holding charge a bit better now, steady around 12.6 volts.

 

I just want follow up with a big thanks to all who assisted here with advice and knowledge. A few weeks ago we had to take our Prius to the service department at Kendall Toyota in Eugene for an oil change and tire rotation. As part of the service they did a load test on the 12 volt battery and sure enough it failed. I had them replace it for $248 minus a $50 coupon I had received at the time of the car purchase. I am happy to report the issue with the failure to engage "READY" mode has been resolved.

 

I agree with your post. I was having intermittent power power and often related to the brake pedal being depressed. Power was intermittent. I took it to the Toyota dealership in Carlsbad, CA and they could not find the issue. I had just replaced the battery with a bosch battery and their recommendation was to install a Japanese battery. That made no sense to me as I worked in a battery line at Sears in my 20's and had become acquainted with troubleshooting charging and starting systems.
It turned out to be that the terminal lug at the positive post was loose. I could wiggle it and couldn't tighten it down anymore. So I broke out my dremel tool and shaved off the terminal sides that grip the post. I eventually tightened the the clamp where it could properly fit the post. Maybe the Japanese battery post is larger than the Bosch post. A millimeter or two perhaps. Have not had a problem since.

 

i think the posts are the problem. where did you get a bosch, how much and what warranty? thanks!

 

We had a similar problem with our 2010 Camry Hybrid. it was my daughters car and I would get this frantic phone call that she could not get the ready light come on. I had it towed to the dealership and they replaced the battery and the small one. it happened again and I drop the car off and told him fix it and call me when ready. after 2 weeks they finally had changed the front engine room compartment harness. after this we never had another problem. could it be ghost in the machine? one could only imagine what was wrong with that harness. it never happen again as long as we own the car. she traded it for a 2014 Corolla.

 

Having a Prius is apparently like having a computer. So we are driving P.C.s, laptops, tablets and cell phones, which I think is a real problem. Wish I would have thought more about it before buying my Prius.

 

They're all like that tho, not just Toyota, and Prius.

 

Just because other cars aren't hybrids and don't have fancy displays (and analog gauges) doesn't mean they don't have a whole bunch of electronics and electronic control units.

OBDII - On-Board Diagnostic's System - Does My Car Have OBD-II? The Connector and
Communications. has been mandatory on cars in the US since 1996. CAN bus - Wikipedia, the free encyclopedia is widely used regardless of whether or not the car's a hybrid. The bottom of How to Diagnose a CAN Network claims that virtually all cars and light trucks since model year 08 use it.

http://www.nytimes.com/2010/02/05/technology/05electronics.html?_r=0 says

How it Works: The Computer Inside Your Car might be insightful.

 

Every car ever made can suffer a mechanical failure. Every car made today has an electronic ignition system which will not start until a diagnostic test passes.

Prius is a very reliable car.

 

I had this problem, last night, carrying on until today (which led me to this search).
Before you blame the brake switch, battery, and take it to the dealer, check fuse 14 under the dash panel. Solved my problem.

 

what is that fuse for?