I have 2001 Prius. I have a voltmeter on the panel, and when the car is off, it shows 12.1 or so. During start start it goes down to 11 or so, and when the engine starts it goes up to 13.6. So far everything is normal. But after a few minutes, the voltage goes down to 11.5, and then it keep going down. At 10.5, the square around the D for Drive disapppears, and the car won't move. Then the screen starts to flash, and everything dies. But after 15 minutes I could start the car again and the cycle starts over. The warning triangle is lit, and there is a message on the screen with three icons, PS, main battery and car with triangle. Last one is marked. I can't see any codes. The car is at a non toyota shop, and the guy there thinks it might be the alternator. Any ideas? Also, I thought that the 12v system was fed from the high voltage system, at least when the combustion engine is nut running.
You are right. There is no alternator in the classic sense. Measuring 12.1 when everything is OFF is not a good sign for battery health; neither is the 11 reading when turned ON. How old is the battery ? If it's over 5 years, just replace it......and charge the new one before installing. It is possible that the battery is shorting out after running a while and the inverter that charges it is shutting down to protect itself. You need a healthy battery in order to test the inverter. P.S. This "mechanic" obviously knows nothing about hybrid cars. Find a different one.
The battery is 2-3 years. The 12.1 was after a few cycles of this, it has usually been a bit more. If the battery shorts, would it recover enough in 15 minutes to be able to start the car again?
That, or any separate voltage regulator, would be a good guess for a traditional non-hybrid. But the Prius doesn't have an alternator at all. Move this car to some shop that has Prius-specific experience. Otherwise, the guy will be learning on-the-job from your car.
Maybe. Depending on exactly where the measurements are being taken, it also could be a loose connection. The main point IS: If you are going to be guessing and trying to fix this yourself, the 12 V battery is a LOT less expensive than the other likely parts.......like the inverter itself.
A comparison of cost-to-replace ought to also factor in likelihood-of-being-problem. Replacing part A because it costs way less than part B, with precious little evidence it will solve the problem, is like the story about looking for your keys under the streetlight even when that's not where you lost them, because the light's better. It sets you back the cost of part A, and then you can start solving the problem. Here's an example of a problem that would likely be solved really fast by reading the codes. Techstream is easiest; ScanGauge can read the HV-related codes if you program in some PIDs you can find by searching these forums. Offhand, my money would be on insufficient cooling of the DC/DC converter, leading it to shut down after some minutes of operation, because it's too hot. That would be confirmed by reading the code that says I HAVE SHUT DOWN AFTER SOME MINUTES OF OPERATION BECAUSE I AM TOO HOT. That right there can take the place of a whole lotta guesswork. And we have lots of experience with thermally protected electronics shutting down when they're hot and resetting when they are cool. Examples of batteries routinely shorting out and then unshorting are (I won't say nonexistent just because I know of none) harder to come by. -Chap
Thanks everybody. I found the shop using Google Maps. It was open on a Saturday, and half a mile from where the car was stopped for the second time. On the road, right in front a of a traffic light. At least I was luckily in the right-most of two lanes. Perhaps he better choice would have been to get it towed to Toyota. I think I will call the mechanic on Monday, and tell him to read the codes. I'll also tell him to check the inverter coolant. Otherwise, i'll have to get the car towed to Toyota. I read a little more about the hybrid system, and I now understand that the MG1 feeds the high volt system, and the DC/DC converter part of the inverter feeds the 12v system. I think that the voltage cycle I observed is consistent with the DC/DC converter shutting down. I can find three codes P3125 263 264 and 265 relating to the DC/DC converter. 284 means inverter is overheating. The mechanic certainly has some kind of OBD reader. I don't have a Scanguage, but I have a OBD adapter and Torque Pro on my Android Phone. I got the standard readings, but I never configured the extendend ones.
Good research. One minor point: MG2 also feeds the high volt system, any time you're slowing down. And MG1 is sometimes fed by the high volt system. That's why they're both called motor-generators; they can play both roles. -Chap
And there is precious little evidence that any good will be accomplished by taking a few words out of context and criticizing that part without the associated qualifications. If he is going to read the codes and look them up, he won't be blindly guessing. If he is going to take it to a shop, he won't be trying to fix it himself. Therefore my comment doesn't apply in this instance. Give it a rest, please.
PriusChat's a shared resource; future readers come and look at old threads, and everybody benefits if what they find there helps them get to the solutions of their issues with a minimum of unproductive effort and expense. It's not that I disregarded that sentence; my aim was just to give the OP some useful help without belaboring it. But in a bit more detail: 1. A comparison of the price of the battery to the price of the inverter is a bit farfetched. For something likelier to be the cause of the issue, the price of the inverter pump is roughly comparable to the price of the battery. But when you adjust each for probability of solving the problem, one becomes the far better bet. 2. "if you are going to be guessing and trying to fix this yourself" combines two independent decisions that are better uncombined. One of the chief benefits of doing your own wrenching is the opportunity to do proper diagnosis. Shop technicians work on an unforgiving clock and generally do little or none; when they throw parts at the problem until it seems fixed, it doesn't come out of their pocket, but yours. When it's your car and your work, you have both the ability and a strong incentive to properly diagnose rather than guess. If you're going to guess, might as well not be fixing it yourself; any shop can do that. On the other hand, there's value in doing even just the most preliminary diagnosis yourself, whether or not you intend to DIY. What you learn in diagnosis may inform your decision whether the problem is one you want to DIY or not. And even if you then go to a shop, you are better informed and able to judge whether what the shop is telling you is plausible. -Chap
What is the inverter pump? What the repair manual manual calls the HV Water pump? I can't find any code that directly relates to the sensor, so I guess one would have to remove the bumper and left headlight, then have a look at the pump. Does it vibrate or make any detectable noise?
I absolutely agree with that. Alas, many people ignore that advice. What advice would YOU give to those who express no desire or ability to "do it right and learn something in the process", instead insisting on just swapping out parts until they get lucky ??
I guess I should have done a more research before posting, but I wanted to get as much info as possible before Monday, when I talk to the mechanic again. I want understand what is wrong, and how the car is supposed to work. I don't want to fix it myself, unless it is very simple. I can do engine oil change, that is about my level..
Did we accomplish that.....among all the smoke blowing around ? What we can say for sure is: That mechanic knows nothing about hybrids and you need to find a shop that does.
Yes, the crucial thing I got from here was the inverter is involved in what I was observing. About the mechanic you are right. But my dealings with multiple Toyota shops unfortunately has left me with the impression that they treat the car mostly as a non-hybrid. I've asked on Toyota Club Sweden's forum, but the guys there are interested in other Toyota models You would not happen to know a good Prius shop in Stockholm?
I just continue assuming they might be reachable, and pointing out that reading the trouble codes might not be too hard, and save them either a bundle of cash, or hours of misplaced speculation about other causes, or both ... even if they end up spending the few € it takes to look them up in the repair manual, which is a small fraction of the bundle of cash it might save them (either on DIY, or on shop techs floundering about.) Sometimes it even works. Sometimes it doesn't work right away, but works for some later reader who happens along on the thread. But in this case I notice the OP is looking at the repair manual, and showing positive signs of initiative. Exactly. Often you can tell if it is running just by looking at the inverter coolant reservoir (the skinny one, next to the inverter). On Gen 1 it is easy, the coolant returns through the hose at the front of the reservoir, the reservoir is see-through, and there is a little baffle at the front. When the coolant is flowing, there's a small waterfall there, you can see a 1 or 2 cm step in the level. When not flowing, of course, it levels out. Low or absent flow could mean things other than the pump (clogged passages, for example) ... but the pump is a known wear item, if you don't know that it's been changed, 2001 is a pretty old car. It's also not all that much harder to change than an oil change, if you have new coolant to refill with, and can follow steps in the repair manual. It's more tedious, with removing the headlight for access and all. I still wouldn't advise you to start on it without at least seeing impaired flow, or an overheat code, to make sure I'm not barking up the wrong tree. Anyway, looking for signs of flow is an easy check. -Chap Edit: forgot to mention: the Gen 1 HV coolant pump should be constantly on whenever the key is in the ON position (car does not have to be READY).
It's been a while, but I just wanted to followup. The inverter coolant level was very low. I put in a liter, and then about 3/4 l more. The problem I described went away. I have been watching the coolant level since then, but there does not seem to a leak.
I'm new here so please forgive me if I don't for my I' s and cross my t's. This seems like the closest thread to my problem. My wife has 2003 prius 150,000+ miles. About a week ago she was sitting in car with a/c on. Car shut off and check engine came on. Maybe other warnings also but she's not sure. When she got home she parked it and when she went to leave again she had the check light, PS, main battery and triangle with exclamation. Tried to start it to put in garage but not enough juice so we jumped it. Then the key got left on a and the display wouldn't show anything. I read a little and decided to replace the 12v. Also I emptied and filled the radiator coolant, inverter coolant and the transaxel fluid. We haven't had the car long and had only done an oil change on it. All of these I did by watching many many videos. It seemed all went smoothly except inverter coolant replacement was a nightmare. Eventually whining stopped, from the car also and seemed to drive fine. No warning light at all. Soon as my wife drives it she's on freeway and cars nothing down then at 53 shuts off. This is with a/c on. Check engine light goes on. I have her drive it but watch temp and noise. It does fine 70+ as long as no a/c is on but check engine still on. I tried obd2 scanner but it says link failed. Can anyone tell me what this may be and how to solve it without the dealers son going to college instead of mine. Thank you for any help u can provide.
Wild guesses probably won't get you anywhere........since there is scant little actual information or data to go on. ALL professional maintenance costs have gone WAY up lately, just incase you haven't noticed. Sometimes you just have to bite the bullet; I think this is probably one. After checking all of the fluid levels and the voltage of the 12 V battery.......you probably need to make and appointment at a dealers shop. Disconnecting the 12 V battery for a few minutes might reset things and make it driveable for a short while. That might make the code reader work too. Good luck. Any thoughts of trading it in ??
This is one of the most notorious bad user-interface design bits on the Gen 1 Prius. When that screen comes up, it always has those three icons; the ones that matter are highlighted red. People rarely notice that, and just say "I got the PS-main battery-triangle thing." If it comes up again, look for which of the three are highlighted. Not every obd2 scanner works on a Prius, especially a Gen 1, which mashed together several different pre-CAN computer modules, some even talking different protocols on the same wires. But getting the codes will help you a lot; the car is trying to tell you what's wrong, and that can save you a lot of time and money over guessing. A lot of people have found cheap ways of using Toyota Techstream on an old laptop if they have one; you can search lots of posts about that. That's easiest by far, especially on a Gen 1, where other available options require you to be a bit of a geek. The PriusChat shop sells a thing called ScanGauge II, but it's actually more money and harder to use; you need to contact the manufacturer for a free, different cable that works in Gen 1, and look up a bunch of Prius-specific codes and thumb them in with the four buttons on the front. Some people use phone apps and load in Prius codes too, but all of that is more technically demanding than using Techstream. You should also know in a pinch that almost all the computers in the Gen 1 Prius have an alternate way you can ask for codes to be blinked out on the dash lights. You can also find forum threads about that here. However, two of the computers, the "HV ECU" and the "Battery ECU", do not have any light-blink alternatives, they have to be read with Techstream, or another scan tool with Prius data loaded in. -Chap
