[MR. Seth]

Hey everybody,

I'm going to do a complete coolant replacement. I have found plenty of information regarding replacing the engine coolant. But I haven't found much for the power control unit. If you don't know, there is a separate coolant system for the power supply of the hybrid system. I'm seeing a lot of replace at 100K or 5 year recommendations. Well I have a 2012 CT 200H F sport. So I figure I am due. I've read the coolant becomes corrosive and eventually eats away the interior of your radiator, heating core, etc. I know there is a petcock valve that allows the coolant to be drained easily for the engine coolant. I just can't find anything on the power control unit. I haven't lifted the car up yet to take a peek but I was wondering if anyone else has replaced this themselves? Can it even be flushed? does it even have its own water pump? I plan on flushing the system with distilled water and then filling back up with fresh antifreeze. I do know how much fluid it takes however.

Any quick tips that would save me some time that you all have found out would be tremendously appreciated.

Also, what is your antifreeze of choice? I like Amsoil for other fluids but haven't done much research on their antifreeze.

Thank you,

Seth

Power Control UnitInitial fill 2.2 quarts
With Recirculator SystemInitial fill 7.3 quarts
With O Recirculator SystemInitial fill 6.9 quarts

 

[MR. Seth]

Well I went ahead and went with Amsoil Ethylene Glycol 50/50 Pre-Mix Formulation. https://www.amsoil.com/shop/by-product/other-products/antifreeze/passenger-car-and-light-truck-antifreeze-and-coolant/?code=ANTPC1G-EA
They have great products and I have build a bit of brand loyalty with them. I also went with the Dominator Coolant Boost. https://www.amsoil.com/shop/by-prod...reeze/dominator-coolant-boost/?code=RDCBCN-EA .

I haven't done the flush yet but I intend on giving updates just in case I can help someone else. The coolant boost sounds pretty nice. It is supposed to heat your engine up faster in the cold and cool it down quicker when it is hot. They boast 40% quicker heat up to where your thermostat starts allowing hot air through your vents. I also plan on installing some sort of block heater or oil pan heater. I will start a separate thread for that however.

I'm not the only one who has had their 2012 model make oil starvation noises when it is cold. I plan on going to have the "cold soak" fix done if it is still in warranty. Hopefully this will aid in keeping the engine happy with me in the absolute coldest of weather.

 

[MR. Seth]

Well I have completed to coolant flush. I decided not to try to mess with the power control unit. I read a couple posts online mentioning it would require some specialized computer equipment from the dealer. I'll save that for them. But I did find the engine coolant flush to be entirely easy. If I were to do it again it would be much faster. I had started taking off panels under the engine to get to the petcock. When actually you can get to the petcock valve with your hand without removing any panels at all. (MAKE SURE YOUR CAR IS COLD BEFORE YOU START OR YOU WILL BURN THE EVER LIVING CRAP OUT OF YOURSELF, ALSO USE JACK STANDS). I highly recommend getting a small rubber hose or something to connect to the end of the petcock for the drain. This will make it much easier and save yourself a huge mess. There is a little oval cut out under the front end of the car that you can reach your hand through to turn the valve. It is inches from the drain. I have smaller hands but it was very easy for me. Now since it is a pressurized system you have to unscrew the coolant reservoir cap before it will really drain. I left the cap to just rest on the reservoir to prevent from dust getting in there. After I started draining I left it drain for several hours to make sure everything was out. I made sure to go ahead and lower the car to make sure the drain was at the lowest point. After nothing was dripping anymore I jacked it back up and closed off the petcock valve. I then refilled the reservoir with distilled water. Do not use tap water! I kept filling until the water level was at the full line and it was holding the level there. I turned the car on and put the heat on the hottest setting. I waited until it started blowing hot air in the cabin and then started a timer for 5 minutes. Once the 5 minutes was up I turned the car off and let it sit several hours. I didn't want to burn myself. When I came back out I repeated the drain sequence. I then made sure the petcock valve was closed. and SLOWLY started pouring the amsoil antifreeze back into the reservoir. I used a funnel to keep from making a mess. Now the thing that sucks about their antifreeze is that it isn't colored. So it is hard to see the level on the side of the reservoir. I made sure I didn't see anything dripping under the car. I lowered the car and kept filling until It was holding steady at full. I've read the system is self burping. But just in case I made sure to massage the coolant lines with my hand to get any extra bubbles out. I locked the cap back on and started the car. I haven't had any trouble and it is running fine. I haven't added the "dominator" coolant boost yet. I was going to keep checking the level and run it for a couple of days first.

Now again, I did this because it is recommended to change your coolant every 5 years or 100k miles. When I went to a dealership they acted like I didn't need to mess with it until 100k miles. That was a red flag for me. It seems like they just want to do oil changes and up sell me tires I don't need. It is also nice to take a gander at your under carriage every once in a while to see if any other repairs may be needed. Check for leaks, rust etc.

 

[KKM]

Nice write up. I also have a 2012 but only about 55k on it. Will have to find time to do the change. The color still looks nice and pink.

 

[gamma742]

Once you look under the hood of the CT200h you will notice that it is the same as the 3rd Generation Prius making the Coolant change the same. The original Post is a great write up but I'm a visual guy myself. Hope this helps...

 

[gamma742]

And if you are considering the Inverter Coolant...

 

[Pete44]

Mr. Seth, great stuff, thanks. 2013 CT200h at 98,600 mi. Just changed oil (Amsoil....I think I wasted money and should have just gone with Mobil 1. I sent oil to Blackstone (only 13k on Mobil 1. Last time I sent 20k Mobil 1 oil, Blackstone noted that I had better oil than most 10k changes in this type of vehicle, and plenty of residual base in the oil. I used Annual Protection Mobil 1 0w-20). I know most people wouldn't wait 20k. I get it. Just know that Blackstone analysis was better than most 10k. I warm religiously before driving, drive very easy first few miles, and use Purolator One filter (5 micron....better than Purolator Gold). Anyway, all that said, I watched the above inverter coolant change video for the 2010-2015 Prius, and changed the inverter coolant as per instructions. I watched the inverter coolant get drawn into the inverter and refilled a few times and redid. All was good. Drove about 2.5 hours home, stopping a few times. Drove the next day a couple of miles. All good.

Then, this morning, went to start car and it would not start. All lights came on with alerts and warnings and "check engine" light and car wouldn't even try to start. It seems there is something wrong with the inverter. I hope to God I didn't damage my inverter, and really hope it's just the "computer thing" they say the dealership does with the inverter. For all I know, however, some air got trapped in the inverter coolant pump and the pump burned out or something.

If anyone knows about this, I'd really appreciate some advice. No leaks under car. All was done properly per video....but no dealership computer system for inverter coolant change. Uggh!

 

[Haha_jizzjizz]

Damn. That was brave. You have a way to check for codes? Is the inverter reservoir still at the correct level? Did you follow these steps? May be possible that all air was not bled.

 

[Pete44]

Update: I've read a lot...but no luck finding any solid answers. This shouldn't have happened from everything I see. I refilled the reservoir, turned car on

View attachment 60710 Damn. That was brave. You have a way to check for codes? Is the inverter reservoir still at the correct level? Did you follow these steps? May be possible that all air was not bled.

Thanks for the info. I don't have an OBD2 scan reader at this time, but when I try to turn the car on, there is no noise in the pump. I assume the pump was fried from some air in the system and hoping (very much!) that I haven't damaged the inverter. I refilled each time and turned the car on and off. Lots of air bubbles came out and I cycled and refilled a couple of times, then no more air bubbles even with car running. Drove for 45 mins, stopped, drove another 1.5 hours, stopped. Drove the next day 10mins. No signals, no lights. Now all the lights come on. When I turn it on with start button and move immediately to the coolant pump, I hear nothing. I've checked the pump fuse (per someone on Prius chat identifying the 10A pump fuse) and it's good (unfortunately). I'll read through the screenshot carefully. I may have gotten the tank too low while cycling and got air into the system. I'm remote. Nowhere near a dealership (CO Mountains remote). Hour and a half to nearest Toyota dealership. I guess I'm going to have to replace the pump, but just trying to make sure that I can refill the fluid after that and get the system properly purged. Do you happen to know if the OBD2 reader can differentiate between a bad pump and a bad inverter?

 

[Haha_jizzjizz]

Update: I've read a lot...but no luck finding any solid answers. This shouldn't have happened from everything I see. I refilled the reservoir, turned car on


Thanks for the info. I don't have an OBD2 scan reader at this time, but when I try to turn the car on, there is no noise in the pump. I assume the pump was fried from some air in the system and hoping (very much!) that I haven't damaged the inverter. I refilled each time and turned the car on and off. Lots of air bubbles came out and I cycled and refilled a couple of times, then no more air bubbles even with car running. Drove for 45 mins, stopped, drove another 1.5 hours, stopped. Drove the next day 10mins. No signals, no lights. Now all the lights come on. When I turn it on with start button and move immediately to the coolant pump, I hear nothing. I've checked the pump fuse (per someone on Prius chat identifying the 10A pump fuse) and it's good (unfortunately). I'll read through the screenshot carefully. I may have gotten the tank too low while cycling and got air into the system. I'm remote. Nowhere near a dealership (CO Mountains remote). Hour and a half to nearest Toyota dealership. I guess I'm going to have to replace the pump, but just trying to make sure that I can refill the fluid after that and get the system properly purged. Do you happen to know if the OBD2 reader can differentiate between a bad pump and a bad inverter?

Most of these refer to inverter performance and temp out of range. But the last one is for pump performance.

 

[Pete44]

Does anyone know a way to reset the electrical system? I've disconnected the 12v and hybrid battery (pulled the orange handle out with the "breaker"built into it on the back of the hybrid battery pack). After disconnecting all this and reconnecting, same lights come on and car won't start. Anyone with any ideas? I hate to change the pump only to find out the car still won't start. Also, just ordering an OBD2 reader doesn't seem likely to differentiate exactly what's going on. But that said, maybe I can reset the system with that.

 

[Pete44]

View attachment 60711
Most of these refer to inverter performance and temp out of range. But the last one is for pump performance.

Thanks! Gotta probably get an OBD2 reader.

 

[Pete44]

How are you pulling up all that info?? Those screens are really valuable info. I've saved the photos and really appreciate it. Do you happen to know if a scanguage 2 (or 3?) will pull up codes? I'm probably going to go ahead and make the jump to getting a scanguage 2 (or 3....can't recall what the latest is) because I'd like to monitor all the temps while I'm driving with radiator blocked in the winter, etc.

 

[Haha_jizzjizz]

How are you pulling up all that info??

Go to the engine and tech sub forum. I have this program there you can download. Just unpack and double click the index.html

 

[Pete44]

Go to the engine and tech sub forum. I have this program there you can download. Just unpack and double click the index.html

Thanks Haha. I have a mac and downloaded and unpacked it, but it doesn't work on Mac, it appears. nevertheless, a maintenance manual would be gold right now and really appreciate you posting that.

 

[Pete44]

I did manage to get something to happen. I borrowed a friend's OBD-II reader and plugged it in. Weird: I didn't clear any codes, but tried to read them and it said "0" codes. I went through a lot of menus, but was very careful not to clear codes (so that diagnostic info would not be lost). After much mucking around with the OBD-II reader, and after putting a booster on the 12V battery, the car STARTED !!! I couldn't believe it. I was even able to verify that the inverter coolant pump was working (could feel flow in the line). Nevertheless, I got a "Check Hybrid System" on the dash and the yellow warning/exclamation symbol. I shut down quickly. After more turning on/off, starting a few times, etc, I was able to retrieve 3 codes from the engine (there were no transmission codes).

 

[Haha_jizzjizz]

can the reader read live data also?

 

[Pete44]

Aw crap. Now I'm looking at codes on your list and nothing even matches in format. This is a cluster! I don't think it's a good idea to try to drive to a Toyota dealer (closest is 1.5 hours away, through the mountains with many hills to climb). I'm perplexed. Nevertheless, whatever is going on (I'm pretty sure it must be air in the inverter....can't think of anything else that could be causing an inverter system problem right after I changed the coolant). So maybe I could spend 3 hours driving to Toyota dealership....letting inverter cool every 30 mins for 30 mins...or some such. I'm so pissed at myself. I think there was a point where I was cycling new coolant from the reservoir into the system, where I may have had it going to long and it seems like I remember the reservoir going about empty at one point. Then I filled it again and repeated till no bubbles and it stayed full. So I wonder if I drew some air into the inverter with the pump, and so the inverter isn't circulating coolant like it should and either is toast or threatening to be. ?? At this point, I'd be happy to spend the money at Toyota to have it fixed properly. Only trouble is, I don't know if I trust them to fix it properly. But their diagnostics might be helpful since none of these codes seem to match any of the ones on the list Haha_jizz-jizz posted up. But PO118 does say "Engine coolant, temp sensor 1, circuit high" which seems to point to an elevated temp sensor, which is likely the inverter coolant circuit.

Anyone with ideas or input? Thanks to the community! and Haha! I really wish I could pick the car up, nose down, and shake the hell out of it to get any air out of the inverter.

 

[Haha_jizzjizz]

 

[Haha_jizzjizz]

You're gonna have to take it to the shop unless you have a odb2 diagnostic unit that show live data. Your car is in fail safe mode and in the reason for the lights. Strange it threw the maf code and engine temp code. Clear the codes and drive it for 10 minutes and see if they come back.