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Prius Starting Problem

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Hi,

My son is running a leased 2011 Prius with about 35,000 on the clock which has developed a strange problem that I hope will ring bells with someone.

Starting with a cold engine is fine but if the car is stopped it won't restart when warm, even if it's only had a short run. When the Ready button is pressed with the brake pedal down it goes through flashing all the lights on the dash but then shows the amber light on the Ready button and doesn't show Ready on the dash. If he repeats the operation it does eventually start but yesterday it took 28 presses to get it going after a run of about 2 miles follwed by 20 minutes rest.

It's been in to Mr T several times and they have checked the 12v Battery and replaced the brake pedal switch. They now seem to have run out of ideas and have asked him to record when it happens in the hope that they can see a pattern.

Any ideas?

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How do the door locks sound? Nice satisfying clunk or a slow lethargic kachunk? I'd still suspect the 12v Battery personally...dealers don't have a great track record of detecting problems with these before they fail.

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Overheating inverter?

Has the vehicle had any inverter work carried out, in addition to the recent inverter software recall? There have been some reports of failing inverter pumps on the US forum, though mainly on the gen2. When the car is in Ready can one see movement in the inverter reservoir? (take the top off to see and obviously don't get it in your eyes etc). There should be a slight vibration or swirling. Apparently it is possible to get air locks in the system (inside the inverter) if the fluid has been changed and not bled correctly. The inverter can get very hot when running and if there are air locks I guess that could cause it to over heat and the car refuses to start to protect itself?

Failing that, is the vent on the rear passenger seat blocked or covered by a coat or blanket by any chance?

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It's been in to Mr T several times and they have checked the 12v battery and replaced the brake pedal switch.

Have they changed the 12v Battery?

Often a duff 12v Battery passes all of MrT's Battery tests with flying colours.

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It's been in to Mr T several times and they have checked the 12v battery and replaced the brake pedal switch.

Have they changed the 12v Battery?

Often a duff 12v Battery passes all of MrT's Battery tests with flying colours.

The 12v should ALWAYS be the first thing to independently test if there are any weird problems with a Prius. Whilst the car in question is only a 2011 with low mileage, we don't know how it's been kept on if the 12v has been allowed to run empty and be damaged. The are a number of well reported ways to test a 12v on a Prius that doesn't involve Mr T or using the onboard computer.

I think the Ops relative should investigate the 12v first on their own and at least report back or we'll just be guessing and speculating with no feedback.

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Thanks for the suggestions.

The video is pretty much what I remember from watching my son trying to start it at the weekend, and I see at the end of the thread the problem goes away after a new Battery.

The only Battery test we had time for was to try lowering the windows when the car wasn't showing Ready and they seemed to work as normal. I'll send him a link to this thread and see if we can have a closer look at things next weekend.

Thanks again.

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Like the others I would go for the 12 volt Battery. Get Toyota to replace it if it is still under guarantee, or get down to Europarts and get a Bosch Silver 4 year guarantee Battery for about £55. Much better than the Toyota ones. How old is the car?

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Update.

I had the opportunity to check my son's Battery today and found it very low.

After a short run followed by 20 min rest the standing voltage with all load turned off was 9.8v and it dropped to 9.0v for an instant when the start button was pressed. This time it did start without a problem and the voltage rose to 14.3v.

Armed with these figures he is going to go back to the dealer to get them to replace the Battery.

Michael - it's a 2011 Gen 3

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The 12v Battery in a Prius is very small, only there to keep memories and to start the hybrid system. If the car isn't getting used enough to keep it properly charged, it'll probably be worth investing in a charger that you can connect every so often. A completely flat 12v Battery will be permanently damaged so you really so need to avoid that situation.

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Ah, 2011 = about 3 years old. That is a bit young for a Battery to go, but not unusual. Mine went wacky at 4 1/2 years old . Locking goes from chunck chunck (hard sound) to choose choose (soft sound). Wipers and windows goes soft and flabby.

Simple solution = Europarts = Bosch Silver 4 year guarantee Battery = £55 = peace, life, and no stress.

Or, get Toyota to replace it because it should never have ever been on the car in the first place.

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An update on the story......

After I took the voltage readings early in September (see above), son informed the dealer and arranged for the car to go in for the fourth time. He also took his record of over twenty failures since his previous visit but again the garage tested the Battery and said it was OK. This time though they did agree to change the Battery anyway and there have been no failures since. Problem solved.

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Given that this problem arises again and again and again, I am amazed that Toyota still can't get it. That 12v Battery is rubbish. In a normal car a Battery will last 6-10 years. In a Prius it is almost always the problem when things 'are just not right'. You would think any mechanic reading this web site would know that.

Pleased it is fixed. All that stress and worry for a simple £55 fix.

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Given that this problem arises again and again and again, I am amazed that Toyota still can't get it. That 12v battery is rubbish. In a normal car a battery will last 6-10 years. In a Prius it is almost always the problem when things 'are just not right'. You would think any mechanic reading this web site would know that.

Pleased it is fixed. All that stress and worry for a simple £55 fix.

Not sure what 'modern' normal cars your referring to getting a 6-10 year Battery life. You'll be lucky for up to 5 years in anything made in the last decade since the introduction of canbus systems etc. I bet a lot of 'failed' batteries would still be ok for years in an older vehicle which isn't so Battery voltage reliant.

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Michael,

£55 sounds great, Mr. T changes the Battery for £95. Is this Bosch Silver batter vented as well?? Or where do you stick that little tube for ventilation? Thanks.

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1st Generation Prius were particularly notorious for failing 12v batteries because:

  1. they were only 35 aH
  2. the Gen 1 had a surprisingly high drain when parked, worse than Gen 2 or 3 despite not having keyless entry
  3. no one realised how easily they went flat at that time
  4. they'd usually been left fully flat by the time they came off the ship
  5. they sold very slowly, so they'd have been flattened for a lot of their time at the dealer before being sold.

My first Gen 1 needed a new Battery by 1½ years old (replaced under warranty).

My second Gen 1 had a new Battery before I got it (at 6 months old), but it was still in the car 9 years later when I sold it! It was just beginning to show first signs of ageing on a cold day on the No. 1 standard test (all 4 windows in non-ready mode).

That one had only been flattened just once, when I had to leave the key in to enable the car to be left in neutral in a robotic car park in London. At the end of the day, Battery was flat (for some reason leaving the key in, even fully off, doubled the standing drain). The car park staff got me going with a jump starter and the car got a good charge going home.

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Just checked, for a GEN 2 and 3 Bosch do a 4 year guarantee one (they do two types) at £47.40p at Europarts. The Toyota one only has a 3 year guarantee.

When you get it there is a little plastic plug (blue I think) at the side of the Battery facing the front of the car when fitted. Take out this plug which is about 3-4 mm wide and there is a vent hole. The black Toyota rubber pipe fits into this to vent gasses away.

The problem is that this flexible rubber pipe has a hard plastic end tube attachment to it which is about 4-5 mm wide, so it is too big. The very simple solution is to get a sharp Stanley knife and carefully shave it down till it is a tight solid fit into the vent hole. Take it carefully and take off as little as you can. Constantly check it as you can shave more plastic off, but can't put it back (like a haircut). I slightly overdid mine, but checking it this morning while checking the spare tyre's pressure, it is still firmly attached, nearly two years later. It is just a push fit.

Since fitting the Bosch I have never had any problems, even though the car use to be left for 5-6 days without driving it.

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Just checked, for a GEN 2 and 3 Bosch do a 4 year guarantee one (they do two types) at £47.40p at Europarts. The Toyota one only has a 3 year guarantee.

When you get it there is a little plastic plug (blue I think) at the side of the battery facing the front of the car when fitted. Take out this plug which is about 3-4 mm wide and there is a vent hole. The black Toyota rubber pipe fits into this to vent gasses away.

The problem is that this flexible rubber pipe has a hard plastic end tube attachment to it which is about 4-5 mm wide, so it is too big. The very simple solution is to get a sharp Stanley knife and carefully shave it down till it is a tight solid fit into the vent hole. Take it carefully and take off as little as you can. Constantly check it as you can shave more plastic off, but can't put it back (like a haircut). I slightly overdid mine, but checking it this morning while checking the spare tyre's pressure, it is still firmly attached, nearly two years later. It is just a push fit.

Since fitting the Bosch I have never had any problems, even though the car use to be left for 5-6 days without driving it.

Thank you Michael, I'll consider this method when I need to replace my Battery. :)

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