Replaced 12V batt. & coolant inverter pump replaced 14 mos ago - still no coolant circulation

I have a 2007 Prius with 124K miles. When I run it in IG-ON mode, the pink fluid in the inverter coolant reservoir is not gently swirling around. Worried that this will eventually cause my inverter to fail.

Was driving a month ago and on my dash I had the Master Warning alert (red ! triangle), VSC light and yellow brake warning light (yellow ! inside circle, inside parenthesis) all come on at the same time. Also, on the LCD touchscreen, the icon of the red car with ! came on. When I got home, I used my OBDII scanner on the car and it threw 3 codes: P0A93 (inverter cooling system performance), P2601 (coolant pump control circuit rang/performance) and P0420 (catalyst system efficiency below threshold Bank 1 -- it's thrown this before and I think it's just from putting in an aftermarket CC in after mine got stolen a few years ago).

Went on this forum to see things I could do to troubleshoot. Put Prius in IG-ON mode and observed that the pink fluid in inverter coolant reservoir is not gently swirling. I already had the inverter coolant pump, engine water pump and water control valve replaced 14 months ago along with a coolant flush (at a local shop not specializing in hybrid vehicles; I know to go to a specialized hybrid shop next time). I called the shop that did the work; they said another one of their customers having the same problem -- had the pumps replaced recently, but fluid in inverter coolant reservoir is not gently swirling in IG-ON mode. Shop said that customer took their Prius to Toyota dealership and they fixed the problem -- something having to do with the electrical solenoid not sending power properly to the inverter coolant pump. The dealership said it would cost me $200+ tax for them to do diagnostics.

I called a hybrid shop and they suggested that Auto Zone read the 12V battery capacity. They measured it at just 66% State of Charge ("failed") so we had them put a new 12V battery in. After they did that, the red triangle dash light did go away, but when I run car in IG-ON mode, the fluid in the inverter coolant reservoir is *still* not moving and I don't hear any pump sound. I hooked up my OBDII scanner a couple of times since the new 12V was put in, but no codes are being thrown. The car drives fine, but I'm trying to not drive it much these days because the inverter was very hot to the touch when I drove it (warning lights came on again suddenly) before replacing the 12V.

What should I try now??

Also, adding this because it might have to do with battery system problems: I was rear-ended 3 months ago, and it's possible that some connection came loose when that happened.

Thanks in advance!

 

Thanks so much for your reply! Yes, it looks like the pink fluid in the reservoir is right around the full mark.

It seems like the inverter pump itself is far down under the easily accessible top portion of what's under the hood -- are you asking me to reach way down and try to touch the inverter coolant pump, or just to touch the big silver hood that encases the actual inverter?

 

Thanks very much for the info, and the offer! I drove the Prius a little bit today, and it operated fine, with no error lights coming on on the dashboard. There was a weird sound coming from under the hood intermittently, though (please see my update comment from today in this same thread).

Even though it's great that the weather isn't very warm these days, I'm still nervous about driving a car that I am almost positive has an inverter pump that's not running (as evidenced by me not seeing any fluid movement in the inverter coolant reservoir when the car is in IG-ON mode). I would hate to have to buy a new inverter because that pump isn't working and isn't keeping the inverter cooled down.

 

I have a new piece of information.

Today was not a hot day and I drove the Prius a short distance for a couple of errands. A few different times, I could hear a sound coming from under the hood, roughly in the area where I know the inverter coolant pump is. It sounded like a machine or pump rapidly making sounds at a quick and steady cadence; the sound wasn't quite an electronic sound, but more of a mechanical sound, like a pump loudly trying to push fluid through a pipe. I think it might be the inverter pump struggling to work. The sound would happen for about 10 or 15 seconds, then stop, and then the same sound would happen again, maybe after I started the car up again. I didn't get a chance to pull over, put the car in park, and check under the hood to see if I could find what part was making the sound.

There weren't any error lights on my dashboard while I was driving today. I never drove more than about 40 mph.

Anyways, that's the update.

 

Sorry for the delay; been dealing with the trunk leaking due to the rear-end collision the car was in.

I just tried putting the car in park, running, and felt the inverter pump itself and the hose that connects to it, to see if I could feel any vibration or movement of fluids. I couldn't feel any movement. I could intermittently hear a noise coming from the general area of the inverter pump -- a rhythmic sound that sounded like a motor trying to turn on but struggling. I think it's the same sound I described in my last post. I ran the OBD2 scanner and it gave me one code: P2601 (coolant pump control circuit range/performance), which it has thrown before.

So it sounds like I probably just need to get the inverter coolant pump replaced. Would you guys agree?