Need help with a diagnosis! 2008 Prius. Transmission issues?

I've been sent home 3 times after very expensive 'repairs' (including replacing the main battery) $6,500 so far, being told the issue was fixed, only to have the same dangerous problems appear every time I next go on a long drive (>1hr).

First an orange warning light with an exclamation in parentheses came on, and a few minutes later the big red warning triangle with exclamation mark appeared. Sometimes there's a red light in parentheses but not often. Following the big triangle warning light was a symbol of the car with an exclamation through it in the main display screen, accompanied by a brief "Engine Problem" notification.

There were no symptoms so I drove to the nearest garage and asked if it would be safe to do the 4hr drive back to my home city. He had a look at the codes and said the only warnings were an AC air filter & potential imminent brake failure(!). He checked over the brakes and said they looked fine, so it was up to me but should be ok to get home. He suspected maybe just an electrical connection was loose, or the battery was causing random warnings to appear. The warning lights disappeared on the way home, so we thought maybe that was the case.

All was fine for about a month, then the warning lights came back on. The starter battery was again suggested as a potential cause of faulty error codes so I had that replaced (even though it was relatively new).

When that didn't work I had my local Toyota dealer look at it while it was in for a service. They replaced the AC filter and spark plugs. The lights came back on the next day.

I was told the next step would be to crane the big battery out to look at the engine, which would cost thousands, so the decision was made to just keep driving it and see if any performance issues arose.

The next time I went on a longer trip the car started hesitating when asking it for more power, such as putting my foot down to get it to change down a gear to maintain speed going up a steep hill, or to overtake. First it does nothing, then it's like it's sharply engine braking (even though my foot is still on the accelerator), then it's like it has shifted up a gear instead of down because it has no power until it very slowly climbs in speed enough for the gear it's in to be effective. This is super dangerous because when it happens when climbing a hill it's like I'm very suddenly braking in front of the car behind me; and I can't overtake, even if the car in front is going very slowly or driving dangerously, because at the moment I need power I lose it instead, and end up going the same speed or slower than the car I'm overtaking (not good if the car behind me decides to follow).

It doesn't seem to happen when starting from standstill, when driving around town, or even on shorter open road journeys... only when I've been driving for around an hour. Then it gets progressively worse and more frequent (to the point where even trying to mildly accelerate on the flat led to shifting up & down gears back & forth until I took my foot off the accelerator).

Toyota didn't seem to listen the symptoms at all, and decided the next thing to do would be replace the big battery. I was told it was fixed, and the warning lights had gone, so I felt confident to take it on my next trip. An hour in, the same things started happening - first the lights, then about 1/2hr later the hesitating on hills or when accelerating, and by the time I reached my destination it was happening even on gentle acceleration.

I think I have had the AC on each time but I can't be sure about that... it seems more like an issue with the gears to me though? Either physically, or with how the car is choosing which gear to be in (I have absolutely no idea how that works)?

Help??

 

Thanks for the replies!

"did anyone ever give you the codes?"
- No. The mechanic at the local I went to when I first had the issue out of town said they don't have access to the codes that Toyota do with their readers, so what they had was limited, and Toyota never gave me any of the info they were basing their decisions on. They didn't seem to be paying any attention to detail anyway.

"was the main battery replaced with a new toyota oem?"
- I'm on a disability benefit so it's technically still my mother's car (handed down when she got a newer one). Since there's no way I could pay for the new hybrid battery she actually took it in for that part, so I'm not sure but I'd hope so! The 12V battery is by a different manufacturer but one recommended by the NZ Automobile Association (NZ breakdown service who have a lot of experience & are trustworthy).

"if you have brake codes, it might be the brake actuator."
- I'll look into that, thanks!

"there's no need to remove the battery to look at the engine."
- That's what I'd have thought!

"did you replace the battery twice?"
- Replaced the 12V battery, which was only about a year old, and then replaced the hybrid battery (thanks @jerrymildred for clarifying the differences with the hybrid!)

"loss of power uphill is usually a weak battery or an engine problem, not the transmission, the prius doesn't 'shift gears'."
- The feeling is definitely that of someone shifting gears badly (taking the foot off the accelerator & engine braking, losing speed & ending up in a gear too high for the situation). Would that point more towards engine problem in that case? I'm assuming weak battery would simply not have enough 'oomph' and run slower & slower? (Like my first, early model Prius haha).

"how many miles on her?"
Ooh I haven't looked in a while actually, will check when I'm back at the car

 

"Sounds like the inverter pump which is inexpensive and easy to replace. On short drives the inverter will be OK without coolant flow. But after a half hour to an hour depending on speed, it'll get hot and reduce power and throw codes that light up your trouble lights. I'm shocked that a Toyota dealer would not know this. You should try to find one that is competent. Reading the codes with a Prius literate reader when the indicator lights are on will tell you a lot."
- Inexpensive and easy to replace sounds fantastic at this stage!! That also make sense. I was looking for any lights that would indicate overheating but couldn't see anything, so I was wondering if a single part might be overheating... I'd have thought that was obvious and Toyota could tell me this though too, so I second-guessed myself.

"They should not have replaced your hybrid battery (which is the starter battery, BTW) without a P0A80 code."
-I'm going to go back and ask for a full list of the codes they've got from it, because the whole thing has felt pretty suss from the start!

"The 12 volt battery is not the starter battery. The car has no 12V starter and it has no gears to shift. The 12V battery just runs the 12V system. They hybrid battery spins MG1 to start the engine."
- Ahh thank-you for clarifying. I had thought the hybrid battery started the car, then discovered there was a 12V after all so I thought I must have been wrong. 12V for electrics makes more sense

 

Local mechanic had a look and said no codes had come up at all. Based on this combined with the symptoms he said it’s most likely the CVT?
(not the news I was hoping for!)

 

Ok, so the pump is gently vibrating and so is the hose, but the coolant isn't moving. Well, it's possibly veeeery slowly moving - if I wait about 30sec a little bubble or spec of dust circles back into view, but certainly not moving at any speed. I'm guessing that's from moving the car when I opened the hood...

Blockage in the pipe? When I tried it yesterday with the car in READY the coolant was jumping about, so maybe it's not a complete blockage or one that's moving, which is why I've gotten away with it for so long?

Thanks, good to know. Think I'm slowly getting the hang of the discussion board - finally worked out the reply & quote system! Ha

 

You guys have been amazing. Thank-you!

I finally got details from the Toyota dealership, and as soon as the foreman heard I was asking for records of the codes and repairs he rang asking what was happening. He tried to tell me it's not the inverter pump because there weren't any relevant codes, and that it could be any number of different things causing the same symptoms one after the other, after each of his 'fixes', and wants me to bring it in to him to have a look. He also added that there'd been a P0A80 code that hadn't been recorded because they hadn't charged me for scanning that time... Hmm. The only two codes actually listed by Toyota are P3000 & P0A84.

Needless to say I've lost all faith in this guy, and will be replacing the inverter pump (through someone else) before anything else!

 

His answer to that was that the coolant apparently doesn't move all the time, so looking at it tells us nothing? (I'm going to go with the majority on here saying that it does over his advice at this point!)

I have no idea what they did because the only notes they'll give me are the job details above... When collecting the car the mechanics are too busy to talk, and the receptionists just hand the keys back and say 'it's fixed'. The one time I got through to a mechanic to ask if it was safe to drive with all the warning lights on, and whether driving it without knowing the issue could cause further damage to the car, I think it was an apprentice who'd been working with the mechanic (not the foreman anyway) and they just said 'As long as the lights aren't red it should be safe to drive'. The entire reason I had brought it in at that stage was because the lights were red...! Not encouraging. I'm going to assume they didn't check the plug though because the same codes came up the second time I brought it in.

Sounds like I have a good game plan - sort the inverter pump and check the battery cooling fan, and go from there. Fingers crossed that's it! I will let you guys know how it goes.

On another note: I'm not feeling convinced that there was a P0A80 code since there's no record, and no mention of it until I started talking about another mechanic and asking for code details. Then all of a sudden a point was made to say it was there, just not written down because they hadn't charged for scanning that time... There certainly wasn't one at the start of all of this (both the mechanic I saw out of town at the start of all of this and the AA would have mentioned it when each of them scanned for codes). And I'm sure Toyota would have been happy to sell us a new hybrid battery from the get go if it was there. If one genuinely did show up in the past few months I'm just wondering what are the chances that it could have been caused by an issue with the battery cooling fan that wasn't dealt with all this time?

 

Ah, that’s brilliant to know. Thank-you!