Help with 12 volt battery

1. Have your husband fully-charge the 12V battery while it is disconnected.
2. Reconnect the battery positive cable, then the negative cable. Make sure all connections are tight.
3. Try to make the Prius READY. If warning lights still come on, then the diagnostic trouble codes need to be retrieved. Good luck.

 

Get a simple code reader (I use an AGT OBD code reader, around $30 on ebay) and you can pull the codes yourself. Then clear the codes and see if it starts normally. If not post up your code numbers and we can help you out.

 

DTC P3191 means that the engine had a no-start situation. This is common with Classic Prius. The remedy is to clean the throttle body interior and throttle plate, using the minimum amount of throttle body cleaner.

Your husband should first remove the air cleaner housing for access. Then moisten a clean cloth with throttle body cleaner and use the cloth to scrub off the dirt in the throttle body interior. Rotate the throttle shaft so that the edges and underside of the throttle plate can be cleaned.

The idea is not to flood the throttle body with cleaner.

 

AND......since you originally thought the battery was going bad......what happened with that part ??
Maybe it really IS going bad.
Might want to have it tested.

 

In a way, the OP's experience kind of sounds like the "nope, I'm not going to start" situation that our cars sometimes get into, that seems to be created all in the mind of some one of the ECUs and will (usually) be magically fixed by disconnecting 12 V for a while to reset things. The symptom seems always to be that the engine spins up for several seconds and then gives up, logging a no-start, when there's obviously no underlying mechanical cause for the no-start because after a reset it fires right up.

I had seen the same syndrome in more than one thread in this forum where people had done engine swaps and were then bafflingly unable to get the replacement engine to start (in some cases making so many attempts the HV battery ran down, making a much bigger headache). Then the time I cleaned my injectors, it happened to me too.

I was determined to systematically track down what's actually not happening when that happens, and I got pretty sure the ECM was just plain boycotting either sparks or fuel injection, and my next test was going to be which of those two, when I looked at my HV state of charge and realized I might not even have two attempts left, so at that point I gave up the investigation, disconnected the 12 V and reconnected, and of course it started right up after that. (Phew! I didn't turn it off again until I'd force-charged the HV battery to 80%...)

So I got that close to pinning down the startless-start syndrome, but still couldn't quite do it. But clearly it's something that can happen just because some control module got in a weird state, and doesn't have to mean there's a mechanical issue to fix at all. If that was what happened here, perhaps there was just some fumbling with the 12 V cable that glitched the power while some ECU was booting, and got it into a weird state that way ... just guessing.

-Chap

 

Off-topic, but I guess for the time it happened to me, there might be an explanation where the fuel trim it had learned for my pre-cleaned injectors was just too rich to start after they were cleaned? Hard to imagine the difference was that big though. But before I took them out, the way I had let off the fuel pressure was to let the engine die after pulling the fuel pump relay, so maybe the ECM had forced the trim all the way to 20% rich trying to compensate for that. I still don't know if even that would be enough to completely prevent starting though. If it ever happens to me again, I'll try to pin it down some more.

-Chap

 

$400 ?????

Outlandish, ridiculous price for a small 12 volt battery.
Is there a "battery store" in your area......like Interstate ??
Even AutoZone or the like should be able to sell you a perfectly good AGM battery, maybe with more capacity than the original, for about half that or a bit less.
(If you are not in the US, a bit more than $200 might be required but not TWICE as much.)

 

Could be. You have my sympathy.
Might be cheaper to put on more standard cable ends.

 

Yes, that is the reason.

The Classic Prius battery, being located on the left side of the trunk, has battery terminal polarity that is opposite that of 2G/3G where the battery is located on the right side of the hatch. Further, there are not many Classic Prius around (only ~50K units sold in the US for model years 2001-2003) so there is even less reason for auto parts stores to carry the Classic 12V battery.

If your husband can install standard battery terminals on the existing cabling, then you could install a regular 12V battery and save substantial $$$. You will need a battery that has the positive terminal on the right (as you face the battery with the terminals closest to you) and obviously it has to fit within the physical space available. Since the battery is located in the enclosed trunk (and not in the hatch connected to the passenger compartment as is the case with 2G/3G), it is not the end of the world if you install a flooded lead acid battery instead of the original equipment AGM battery.

 

That seems like a lot to pay for installation, considering your husband has already learned where the battery is and how to get to it.

If the one you have says GS (I assume it does, since you say it's the original small-post option), it is part number 28800-21050 and about $187 if you check around the online Toyota dealers. That has a relatively low capacity.

The higher-capacity option offered through Toyota is the 28800-31290 made by Panasonic, and rated 51 amp-hours. For those interested in maximum capacity, I've never seen any alternate battery discussed in a Prius forum that can touch that. It is pricey though: about $263 online. If it's not what you already have, there's a cable and tray conversion kit, 04003-23147 at about $35, needed only once for a perfect, stock fit.

Since the upgraded one is what was in my car when I bought it, I replaced it with the same last year. Out of curiosity I tested the new one on a controlled discharge before I put it in, and at 51 amp-hours it was only down to 11.25 V, so I think 51 is even a conservative rating. (After swapping, I tested my old one and still got ~ 30 Ah, for an eight-year-old battery.)

-Chap

 

All the service manuals, wiring diagrams, etc., are available online for a small subscription fee at techinfo.toyota.com, or you can get them as traditional books from helminc.com which distributes the literature for most car manufacturers.

At the very least, your car should have come with the owner's guide in the glove compartment, but if that was missing, you can also get it on techinfo or replace the original paper one from helminc.

Welcome to Gen 1 ownership!
-Chap

 

Have you tried putting the battery on a controlled slow charger (the high capacity upgrade battery is labeled for a charge current no higher than 5 amps and for no more than 12 hours, the smaller GS will have lower limits) to bring it to a known full charge, and then taking measurements?

The car charges it with a voltage of no more than 13.8 volts or so from the electronic converter, which amounts to a pretty low charge rate. If the car is used for mostly short trips, the battery might not often be getting a good full charge.

-Chap