Sweetie's Prius is Dead

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Aug 7, 2020
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This morning, sweetie tried to start her Prius and the car was dead. I'm thinking it might be the starting battery that's dead. However, we've had a weird recent history with the car. A couple of weeks ago I was backing it out of the garage and the engine kept dying. After a bit, I got it to run, took it for a short drive, and all seemed to be well. Took the car to the local tech for a thorough exam, got a clean bill of health, and the car was fine until yesterday afternoon.

Yesterday, the car was moved from the garage for a few hours, and then, when started to put it back in the garage, the engine would run for a brief moment and then die, just as it did two weeks ago. Eventually, the car got into the garage where it sat until a short while ago. Sweetie tried to start it and the car was dead. However, the light inside the car that goes on when the doors are opened worked. After a bit, it too died ... now the car is like a corpse. No lights, can't get the engine to react to the key or start button.

I want to get a battery tester. I've never used one. What should I look for or get? We have the usual auto parts stores in the area.

The battery, BTW, is relatively new ... about two years old. I don't want to just buy a new battery as it seems that there's an underlying issue. Any thoughts on what to check, what to ask a repair shop to look for? Give me an old slant six and I'm good, but I'm out of my element with the Prius, Thanks!
 
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Sometimes the inverter pump will fail in a manner that blows the AM2 fuse. When that happens it can cause the symptoms you described.

This article explains it more efficiently than I can:
 
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You mentioned a battery tester. I think a digital multimeter would be handy to have and to run this problem down. More so that a battery tester.
 
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I'd hit it the battery with a volt meter to confirm the dead battery. But no lights and stalling almost always means the battery. Could be the alternator or whatever mechanism they use is not working properly charge the starting battery.
 

FZ1

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This morning, sweetie tried to start her Prius and the car was dead. I'm thinking it might be the starting battery that's dead. However, we've had a weird recent history with the car. A couple of weeks ago I was backing it out of the garage and the engine kept dying. After a bit, I got it to run, took it for a short drive, and all seemed to be well. Took the car to the local tech for a thorough exam, got a clean bill of health, and the car was fine until yesterday afternoon.

Yesterday, the car was moved from the garage for a few hours, and then, when started to put it back in the garage, the engine would run for a brief moment and then die, just as it did two weeks ago. Eventually, the car got into the garage where it sat until a short while ago. Sweetie tried to start it and the car was dead. However, the light inside the car that goes on when the doors are opened worked. After a bit, it too died ... now the car is like a corpse. No lights, can't get the engine to react to the key or start button.

I want to get a battery tester. I've never used one. What should I look for or get? We have the usual auto parts stores in the area.

The battery, BTW, is relatively new ... about two years old. I don't want to just buy a new battery as it seems that there's an underlying issue. Any thoughts on what to check, what to ask a repair shop to look for? Give me an old slant six and I'm good, but I'm out of my element with the Prius, Thanks!
Your old battery may have a warranty so check that first. Get a new battery with at least 700 cca.
 
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Is it always at idle when it dies? My old Subaru had a problem where it would run fine except it would not idle. Turns out it was a bad IACV - idle air control valve. Replaced that 3 years ago, no problems since.
 

Shel_B

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Thanks for the ideas. Went to open the hatch, and it won't open. There's no place for a key to open the hatch. None of the doors but the drivers door opens. No way I can reach the battery now, or remove items from the back of the car.

We called for a tow to take it to the shop. I'll provide the shop with your suggestions. Looks like I'll be chauffering sweetie around this weekend.
 

JHZR2

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Thanks for the ideas. Went to open the hatch, and it won't open. There's no place for a key to open the hatch. None of the doors but the drivers door opens. No way I can reach the battery now, or remove items from the back of the car.

We called for a tow to take it to the shop. I'll provide the shop with your suggestions. Looks like I'll be chauffering sweetie around this weekend.
You can’t manually unlock the rear doors? There is no way to pop the trunk?!? Sounds crazy. Isn’t the battery under the seat? No jumper lugs underhood?
 
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Thanks for the ideas. Went to open the hatch, and it won't open. There's no place for a key to open the hatch. None of the doors but the drivers door opens. No way I can reach the battery now, or remove items from the back of the car.
There is a mechanical release for the rear hatch. Manually unlock the rear doors and fold down the seat. Empty the trunk enough to remove the floor piece. Then you can find the lever (near the latch) to release it.
 

Shel_B

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I am unable to open any of the doors but the driver's door. The battery is not under the seat ... it's in the hatch area. There is a way to jump it from under the hood, but I don't know how ... I suspect the tow driver will know how and will show me. Anyway, the tow people called and they'll be here shortly. Thanks to all who've helped.
 
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Sounds like you've got a gen 2 or 3 with the 12v battery in the rear. Batteries don't last long in the Prius, ask me how I know, and you'll typically see other issues as they start to get weak. MPGs dropping is the first warning sign, as is the ICE stopping and starting whenever it feels like it. My gen 4 is on its third 12v battery in 5 years. Both times they got weak, my mileage dropped 5 to 7 MPG and the ICE continued to run even when the traction battery was at a full SOC. Last time was odd, as I manually charged the battery and it tested bad with my load tester. When I brought it to the parts store where I bought it they tested it and said it was good but replaced it anyway. Once I put the new one in, the MPGs jumped right back up and the ICE stopped continually running.
 

gathermewool

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I am unable to open any of the doors but the driver's door. The battery is not under the seat ... it's in the hatch area. There is a way to jump it from under the hood, but I don't know how ... I suspect the tow driver will know how and will show me. Anyway, the tow people called and they'll be here shortly. Thanks to all who've helped.

If you can create a post on here you can Google/Youtube a solution.
 
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I had to replace the 12V battery on a friend’s 3rd gen Prius the other day ago. The Prius electrical system is almost as frail as a BMW, and hence IMO, don’t jump it the old school way with another car - use a jump pack.

A flaky 12V battery can cause a Prius or any Toyota-based hybrid to act weird.
 
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I am unable to open any of the doors but the driver's door. The battery is not under the seat ... it's in the hatch area. There is a way to jump it from under the hood, but I don't know how ... I suspect the tow driver will know how and will show me. Anyway, the tow people called and they'll be here shortly. Thanks to all who've helped.
There’s a “tab” in the fuse box with a red cover. Connect the positive to that tab and the negative to one of the shock mount nut/studs.
 
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