Need info on replacing the 12 volt battery, 2003

sounds like you might have more than one problem.

no reason the battery shouldn't work, so i would load test it, and reinstall if good. then have them read the trouble codes.

 

The automatic assumption that trouble codes mean the battery is bad sometimes leads people not to read the codes and find out what the car is trying to tell them. Then that's compounded by the codes appearing to go away after changing the battery (because the computers in the car were without power for that time, and forgot they had anything to tell you).

Then the computers notice the thing they wanted to tell you again, and the lights come back.

When the lights came on at just the time the car needed a jump, it's understandable you would think they are related. And it's possible they are (though coincidences do happen). And it's possible the car is really trying to tell you about something that happened because the battery died, but will just keep lighting the lights until you do something about it.

The best way to know is to read out the trouble codes so we know what the car is trying to tell you.

 

I certainly suspect, as ChapmanF notes, that you will need to find a way to have error codes read - and a generic code reader such as the kind found at big box auto parts stores won't read the special Toyota codes, and certainly not those for the hybrid system. Maybe go to your paperwork from the dealer visit and see whether error codes were reported there. Report whatever details might be on the invoice from that visit.

Either way though, step one is going to be to make sure that the 12V system is in order because problems with the 12V will create all sorts of havoc. While knowing current error codes will be useful, it will be better to know what's there with a fully operational 12V.

I would suggest asking around / looking for either A) a local independent repair shop that specializes in hybrids. (I.e. it should not be a "big-brand" national chain or merely one that does general auto service) or B) a local independent store that specializes in batteries. This will be more rare, but I've got 2 of them in Central VA. (I would be surprised if anyone at a place like an Advance AP knew enough about hybrids and their batteries to act as a good sources for reliable service).

Make sure the 12V system is in order and fully functional (a battery that can hold charge, handle load, and is getting appropriate charge from the HV battery when the car is on). Then see what happens. Then get whatever error codes remain.

 

Please let us know what region you live in... There's folks on here that are keeping an eye out for Prius problem near where they live so they can help you fix it. And the folks on here are enthusiasts of Prius, not people trying to overcharge or make a ridiculous profit. Finding a Prius nerd who lives near you is going to be the most favorable price.

 

Pretty sure she put in zip code for location - (29585 - coastal South Carolina).

 

BUT.....doing that without first checking the 12 V battery is a fools errand.

YOU are twisting that recommendation around into an "automatic assumption" which is NOT the point at all.

 

Duplicate deleted

 

Ah, yes... I see that now... Thanks...

 

And why, pray tell, would that be? Please clarify (for the help of new readers) the assumption that makes you say that.

 

There's 10 comments in this thread? How in the world do we know what you're referencing or even asking? I mean asking someone to clarify is fine, but asking someone to clarify in a way that's so incredibly vague we don't even know what you're saying? Please clarify!

 

Out of the ten comments, maybe it is extra likely to be the one that I quoted?

The one that suggested finding out what the car is telling you "is a fool's errand".

Personally, I've always found it leads rather quickly to solving the problem. But if someone wants to tell new readers it's a fool's errand to find out what your car is telling you when it tells you, it wouldn't hurt to unpack the reasons a little.

 

I'm pretty sure that this question really isn't......and just is harassment.

But just incase someone else really hasn't seen the explanation in another thread on here already:
Checking the power supply FIRST is just good troubleshooting practice, regardless of the equipment in question.

And there are no assumptions involved.
It is based on a bit over 50 years of training and experience as an Electronics Engineering Technician.

It is also based on numerous threads here where Prius owners have suddenly had multiple trouble codes show up all at once and the codes seem to be unrelated to each other.......where the battery tested bad and a new one made ALL of the codes go away.

It is also based on the unfortunate people who follow advice like yours and end up replacing hundreds or maybe even thousands of dollars worth of parts to no avail........only THEN to find out that their 12 V battery is going bad.

Forging ahead without first checking the power supply is just BAD practice.
Advising others to do that is just irresponsible.

 

I recently noticed that the "system" here not only blanks out posts BY users who you have on "ignore"......but it also blanks out the quote from one of their posts too, even if you see the rest of the post where it is quoted.

Any chance that you have ME on ignore ?
If so, maybe someone else will have to pass on this information since you probably won't see it.

 

Because all codes are about anomalous readings in circuits. Hiccups created by a bad 12V because it can't supply reliable voltage will show up as errors whether other components are working correctly or not. Unreliable / unpredictable 12V can easily have any of the ECUs showing phantom problems. There's no point in trying to diagnose any vehicle - Prius/hybrid or not, but especially hybrid or any kind - until you have verified that the basic 12V power supply that powers the systems needs is verified good. That was my point anyway. An unreliable 12V supply = chasing ghosts. Start w verifying a reliable 12V, and then move on to whatever error codes remain.

In this case, the OP ended up needing a jump which got the car going. Obvious 12V system issue. It has to be addressed before all else.

 

If what you meant by that was anything like what the Toyota manuals say ("If the voltage is below 11 V, recharge or replace the battery before proceeding to the next step.") then your advice would be sound and I would agree with it. By all means, make sure you've got 11. The car's computers will run just fine down to a few volts lower (at about 9.5, some of them will set codes saying so, which is what they are programmed to do, and means they are still working just fine.)

And if that's what you mean by "checking the power supply", that's great, because that means you won't be advising people to delay their diagnosis, to spend unnecessary Benjamins on battery replacement, or to assume they can't learn anything from their trouble codes, over some question of how many angels can dance on the decimal place after 12.

ALL of the codes go away when you clear them. That's what clearing them does (including by swapping the battery.)

Because the usual situation with multiple codes will be a primary one and several other codes that are set in response to it by other ECUs (something that is covered in the repair manual and often re-explained on PriusChat on people's specific examples), there is nothing very surprising about ALL of them going away and not being seen again until the next time the detection conditions are met for the one that was primary. For a lot of conditions, the detection threshold is hard to meet, and detections will be few and far between in the early development of a problem.

For one example of a code that can take forever to reappear, consider the humble P0401. It is only detected by a test the ECU runs when a list of conditions are met, which in a Prius happens very rarely because under those conditions the engine would typically be stopped. If you are lucky enough to see that code once and you ignore it, you may never see it again. If you followed somebody's advice to ignore it without even reading to know what codes you had, then even if you have the phenomenal luck to see it a second time, you won't even know that you're on your second warning.

There are PriusChatters who are pretty sure the condition that code represents can blow head gaskets. Some who've been down that road would have been happy with some of the advance warning you'd like to encourage people to ignore.

The "numerous threads" you refer to have all followed a common pattern: somebody gets multiple codes showing up (in relationships that are well understood and often explained on PriusChat). Maybe the person doesn't see those threads; for whatever reason, they assume that because the picture doesn't make sense to them, it therefore wouldn't make sense to someone knowledgeable. And then they find these numerous other threads that encourage them to grasp at the possibility that they would be better off in ignorance of the situation.

I've given a bunch of advice here over the years. People who follow it generally get their problems solved, often by doing simple low-cost or free things indicated by the trouble codes they have, when their threads were attracting lots of other posts telling them they "obviously" had X expensive problem. There's the benefit of doing actual diagnosis based on the information in front of you: you find the solution, rather than throwing parts and cash.

Maybe you have an example or two of somebody "replacing hundreds or maybe even thousands of dollars worth of parts to no avail" when they were following my advice?

Or, ok, you weren't that specific, you said advice "like" mine. So, you got some examples of people doing hundred-or-thousand-dollar part flings on somebody else's advice, where you're prepared to clarify just how that advice was "like" mine?

Edit: Josey, you're a much newer member here, and some of the history might be under your radar; mostly, I was responding to Sam above.

As I said, your point about the power supply needing to be "verified good" is sound, provided we stick to a reasonable interpretation of what "verified good" means; the Toyota manuals are useful to get the ballpark.

Some of your claims about how easy it is to "have any of the ECUs showing phantom problems" are exaggerated, and probably the result of reading too many of the threads around here that involve the circular reasoning of "I was so sure those codes were bogus I never even tried to find out what I'd learn if I listened." Sam has a long and storied history in that regard. I hope I didn't sound like I was picking on you.

 

No I don't think you're picking on me and thanks. And I don't know the history of these exchanges, or whatever.

And it may be that my reference to the "phantom problems" is exaggerated. But it's not from reading too many threads around here. It's more a history of people thinking that codes are somehow a diagnosis. "Oh, the codes say the X is bad, so just replace the X." Like contemporary auto computers are omniscient. Unfortunately they're as dumb as a box rocks because voltage readings are all they've got. For gosh sakes a shaky ground can make people think they need a new transmission. For that reason, I do know that unreliable 12V power supplies - hybrid or not - create a wild card situation. And regardless of anything that I may have exaggerated, I won't bother with error codes until I know that a 12V system is sound. And that is even moreso with a hybrid.

But you know that, so please don't think that I think that I'm telling you something you don't know. I bought an '03 Prius 2 years ago, and that's as "deep" as my hybrid experience goes, and I haven't had to do much to it. So as far as the Prius go, my experience is limited - but not my automotive repair/diag experience. In the time I've been here, I do appreciate your input on all all of the issues that show up here. Your knowledge is quite obviously useful and respected.

In the meantime, my advice to Karen was that step 1 is to make sure that her 12V battery/system is sound. I completely stand by that. Codes or no codes, there's no point in trying to have one of these things without a healthy 12V. And I still wouldn't trust whatever codes come out if the 12V is wonky.

 

Excellent, we agree on that, which is why PriusChat is a place where we routinely advise that codes are only starting points for diagnosis, that the 'fortune cookies' listed for them on line or in scan tools do not tell you what the problem is, that the human has to check the things the computer can't crawl out of its box to see, and where we step people through the process from the information they have to begin with—including the codes—to the diagnosis, day after day.

All good points, again, as long as we're reasonable about what 'sound' and 'wonky' mean. Toyota will have you give it a charge if it ain't at least 11, then proceed. The car's analog sensors (all the ones I can remember looking up) operate on a 0–5V scale, and of course the computers themselves are digital circuits expecting a +5V supply, and the on-board regulators supplying those references can do that hiccup-free with their eyes closed for Vbat well south of 11. Toyota's advice is as conservative as you need and then some.

Where it gets silly around here sometimes is when people push "OMG don't even think of collecting any data until we're done arguing about the decimal place after your 12." That wastes people's time, often loses them valuable data, and sometimes detours them into $200 battery expenditures before they even start finding out what's going on with the car.

And anyway, if you do suspect a car might have been seeing transient low-Vbat problems, there are a lot worse places you could look than the trouble codes. A few of the ECUs have dedicated codes they are programmed to set to tell you they have seen a voltage below a threshold (usually 9.5 V), and even more of them do have voltage measurements available in freeze-frames that you can pull. Keep in mind that the computers are still running just fine at 9.5 and up to a volt or two below, so when they record low-voltage events for you, they are giving you information that may well be useful in your diagnosis.

Under no circumstances are you worse off for knowing what the car is trying to tell you than you would be for ignoring it.

 

STUFF IT, Chapman.
Nothing I said is "exaggerated".
I TOLD you in detail what my posts are based on but you continue to ignore that.

Further personal insults will be ignored.

 

You've replied to a part of my post that was responding to Josey.