How to Replace the Inverter Coolant Pump

My mechanic replaced the water pump and thermostat (after an overheating episode caused by him leaving the cap off of the coolant reservoir!) and when I picked up the car and drove a couple 1,000 feet, the warning triangle light /!\ came on, and the message "Check Hybrid System - Stop the Vehicle in a Safe Place."

What could have caused this?

 

What is "latent inverter or MG failure"?

I had a similar overheating issue and my mechanic replaced the water pump, thermostat, and coolant. Then when I picked up the car and started heading home, within a few thousand feet, the warning triangle light /!\ came on and the message "Check Hybrid System - Stop the Vehicle in a Safe Place."

Now it's back at his shop and I'm waiting to hear what he says is going on and why.

Any ideas?

 

Your mechanic replaced the engine water pump, NOT the inverter water pump!

Go back to your original thread for additional help for your problem. https://priuschat.com/index.php?threads/246412/

 

I don't know how much similarity there is in this area of the car, but as your car is a Gen 3 you'll certainly get better advice asking your question in one of the Gen 3 forums rather than in a Gen 2 forum.

 

I didn't see this mentioned, but does the 12v battery need to be disconnected before going about exchanging of the inverter coolant pump?

 

Post #1 makes no mention of 12 volt disconnect. It’s a 12 volt powered pump, you disconnect it’s electrical connection and remove it; doesn’t seem necessary to do any other electrical disconnect.

 

My fluids came out darn clear pink. Does that mean anything (car bought 2 years ago 2006 33k miles no history)? I am associating it with the engine coolant vis a vie if I need to change that out as well or not. The only test I know for coolants is the hydrometer, voltage test, and pH test strip test, and that it looks clear instead of murky. I'm still in the middle of the job, part came today a day early yay. I just need to go out and get tube for burping out bubbles and SLLC. 1/4" ID is correct for the tube yes?

While I'm at it, what is the torque spec for the bolts holding the inverter (both the horizontal one and the vertical ones thank you.

 

I just replace the inverter coolant if there's no history on it. The inverter never sees the type of heat load and cycling that an ICE system does. So I never see any visual indicators that the coolant is old.

Instead, I find white grit when draining and flushing the system.I assume that it's from stuff precipitating out as corrosion inhibitors are used up.

Posted via the PriusChat mobile app.

 

I managed to remove the pump by dropping it down in front of the engine and sitting on the plastic underbody and fish it out from under the bumper; same with getting a new one in there, had more space than trying to squeeze it from the top. Had a hard time breaking the hose seals, used a metal dental pick that isn't sharp (the metal part is parallel to the hose) and worked it by getting in from the little rib area on the hard plastic and forcefully pushing around the hose to loosen.

I just realized that I overtightened the drain plug to 70ft/lbs, I don't know why I did this. Should I back the bolt out and get a new crush washer and torque to spec 29ft/lb? I haven't filled with fluid yet.

I'll tackle the transmission fluid next. Engine coolant exchange looks complicated ( my Prius is JDM without heat recovery system).

 

As a noob car DIY, I would also like to add that to detect if the pump is working, the vibration will be obvious. You just need to touch the hose closes to the pump or touch the pump itself. If it is not obvious, then it is dead.

Another tip, you can flip the reservoir overflow black tube (the end of it) to the up position. Take it out of its holding slot and force the end up. This will enable you to fill well past the full mark. Obviously do not fill above the opening. It prevents excess coolant going to the ground, and you can fill more at a time. Don't forget to put it back in its place when done.

My pump has very little burn mark as compared to another picture I saw posted here somewhere. Even then, the stench in the cabin was overwhelming, it smelled like the burning of fire cracker sticks. This is what lead me to researching on here and discovering the problem; I had no warning lights and the car acted normal (it's winter and short drives). I am salvaging the base and rubber feet as I have discovered during my online shopping that some Aisin replacement pump do not come with the bracket or rubber feet.

And as for my previous post regarding mistakenly overtightening the drain plug, I had to get another washer. And I agree with Mr Guy Mann about changing the coolant, I'm going to do the transaxle and engine coolant next (one after the other). Thanks for all the help on here.

 

Pump replaced as part of recall in 2011 at 63k miles. Now replaced again in 2024 at 145k miles. You can see from the rusted out bracket I'm getting water in the engine bay. Everyone on YouTube rattling off the swap in thirty minutes flat, but it took me an hour just to drill off the stripped nut (bottom left). You can also see a sheared bolt. I wasn't about to reverse-out the third stripped bolt, so I left it there and ziptied that corner to the fuse box.

I bled the system for a good ten minutes and bubbles never stopped. Screw it, I said, there's a million gen2's running on moribund inverter pumps anyway.