P0C73 3 pumps

22 Prius prime with 205,000 miles. I got the P0C73 error. Quick search and it's the inverter water pump. Only 1 dealer within 200 miles has one and wants $700 for the one in stock or $400 to wait a week for 1 to be delivered. Not cool Toyota. So I take wait a week option and also order a $70 eBay pump. Unfortunately, Christmas delayed eBay so the dealership pump wins. I installed the pump and for 4 days and 1500 miles it has no problem. But then P0C73 pops up again. I have eBay pump by now so I throw it in. But I only get 1 day 300 miles out of it before I get the error again. So now I start to troubleshoot.

Yes I bled the air out forever both times and have good flow.

I have 3 flow rates. 2 cause the code.
Flow rate you can barely see in the reservoir does not produce a code. If one of the other flow rates changes to this flow the pending and verified codes can be erased and the triangle! And error message on dash will go away. Permanent code remains.

Very fast flow causes code pending and verified to trigger. Cannot be erased
No flow causes pending and verified code to trigger. Cannot be erased

If no flow condition exists, squeezing bottom reservoir hose and moving hose around will trigger either fast or light flow. Fast keeps the codes and light allows them to be erased.

The water temperature is never really above ambient temperature no matter what the flow rate is or how long that flow condition exists. I obviously don't let the no flow condition last. But I drive 50 miles or idel for 30 minutes and temperature never feels more than a few degrees above ambient temp when I stick my finger in it. Usually can't tell the difference. Temps are in the 50s.

Why would I get fast, slow and no flow with slow being the only one the computer seems to like?
Why would squeezing bottom reservoir hose start either fast or slow flow?

I put it in maintenance mode and drove it 15 miles with fast flow condition. Stopped and restarted car. Slow flow condition started. I erased codes. Drove 50 miles no problem. Parked 10 hours. Drove 10 miles and even permanent code was clear. Drove 40 more miles back to the exact same place I was when I restarted it and cleared codes 11 hours earlier and permanent, pending and verified with triangle! And dash message appear when I stop for red light. I do maintenance mode again. I clear codes but can't keep slow flow so they keep coming back. Finally give up and decide to return home. Get slow flow and erase codes. I approach first red light 15 miles into drive and when I stop triangle! And message return. I pull over no flow. Squeeze hose get fast flow. Keep messaging with it a few minutes starting, killing and finally starts with slow flow. Erase messages and drive 30 more miles to next red light. As I slow dash lights up again. Pull over and have fast flow. Kill restart and get slow flow. Erase messages and drive 10 more miles. Cop pulls me over for no reason. 2 minutes into stop dash lights up. After cop is done wasting my time I mess with hose and get fast flow. Over it so I finish 20 mile drive with dash lit up on fast flow

What in the world can I do to actually find the problem?

Thanks for your help? I am mechanically inclined and have limited electrical knowledge. I'm pretty stumped now. I see dealer throwing parts at it and already have a bad taste because of the mark-up.

 

Continued testing has found additional behavior. The triangle! And dash error along with pending and verified code doesn't necessarily come on when the pump is fast. What's happening is as I stop using the brakes once I basically completely stop, the errors happen. I pull over and pump will likely not be working. If it's not working I can sit on the front of the car and the 0ump will start. I still can't clear pending and verified or dashboard message. I stop the car and clear codes a couple times and I can restart and no problems until I come to a stop again.

So I tested it by putting it in neutral and rolling to a stop. No errors. Put in drive and started moving then came to an stop with brakes, immediate error.

Fluid temperature in reservoir never increased.

 

Final update on my issue. I found a wire loom underneath the battery box that was caught between the battery box and a sharp edge that was being shorted. I did not have a single bad inverter cooler pump. It was a shorted wire. When water would you get splashed up in the compartment it would short it out and I would have problems when it was wet outside. When I hit the brakes and the battery shifted in the box down and put downward pressure I would have issues. Of course I moved the wire away from the sharp edge and fixed the damage. No problem sense. Unfortunately one week later I hit a pig with my car. Ripped the front corner off.