How to Replace the Inverter Coolant Pump

Hi guys i'm new here but my car just through a p0a93 code and the Dealer said it's the pump. I've ordered the pump and coolant that was listed in the OP. My concern is that I have movement in the coolant tank that would indicate that everything is fine??

Can anyone tell me if it should be just a slight flow or an intense flow?.

I'm planning on recording the flow before and after to post for more info if this fixes my problem.

 

It's a pretty slight flow. I need a good light and my cheater glasses to see mine. You should also be able to hear the pump, a very quiet aquarium pump noise. If you have both of these, it may be something else.

Another thing to check is the radiator fan. There are two INF codes for that DTC, one of them leads to the fan circuit. Maybe the dealer missed that.

If it's time to change the coolant anyway, it may not be a bad idea to replace the pump too. I may do that next time I changed the coolant. It's not very expensive and it's very important.

 

It's reported that fresh coolant flows more intensely than aged coolant. I'm going to be testing this out in about 2,000 miles when I change my inverter coolant.

 

Why would fresh coolant flow more intensely?

 

do not know JC, would you think the fluid would break down may be even crystalize.? I have seen photos on PC of small crystalized particles of SLLC in the drain plugs of the inventers but I'm going to try and make an objective observation of my own at the time.

 

I did a search for SLLC gelling and it's very rare, if at all. Some coolants will gel under some chemical and temperature conditions.

 

Well i got a short clip of the flow that I'm getting. Sorry for the audio, man and a buddy bsing while looking at this thing. Also I've noticed the ICE in this car sounds weird to me vs a normal 4 cylinder, could just be me tho.

I'm new to Prius cars and got this a few months back. Sold my 944 Porsche for it.... Got to love babies...

Anyways there is definitely flow going on but see for yourself once i get the video up in the morning.

I plan to record the flow before and after and also pump resistance.


UPDATE: I went out today to get a resistance check on the pump and to check for air in the line. It's 108F by the car's temp meter and the Pump is not functioning at all today. I pulled the connector and there was 12-14V there so it would seem that the pump is breaking down from heat. I'll get a reading on it before/after anyways and a video of the NEW pump to compare with the one above of this pump. Thanks to everyone who commented here.

Ok I got the car drained and the pump removed today, Here are the readings from the old pump.




UPDATE: Ok I got my pump and coolant in today and was able to replace it. This is the new pumps flow and readings. Thanks guys. So far no error after I cleared the codes.

 

I hope this is the proper thread for a bit of additional info on this important part.

We have a 2005 Prius with 123,000 miles, which has been extremely reliable for all these years.
Date: 6 February 2007, Super Bowl Sunday.
Driving just fine at 60 mph on a rural Texas highway, we heard one beep and the red triangle and check engine light appeared.
There were no prior symptoms or indications of anything amiss.
Of course I pulled over and stopped immediately. Since the car seemed driveable, we limped along at slow speed to an exit.
We had the car towed ($110) to the Toyota dealer in Tomball/Kohrville, Texas and put the key in the after-hours box.

Diagnosed Code P0A93 info 346.
Today they replaced the inverter pump and of course put in new coolant.
Total Parts = $171 Labor = $ 452 Environmental charges = $20 and sales tax $16..... total $659

Of course you always pay the most when you are 180 miles from home and in too much of a hurry to shop around. But they were quite prompt and very professional so I am NOT complaining, just sharing the data. Car drives normally again, wife is pleased.

They said it was the original inverter pump, which I think may be correct, although this pump may also have been replaced previously when Toyota had a Limited Service Campaign which ended in 2013, I think. I will try to be vigilant and replace the coolant at 170,000 mles.

 

I had my inverter coolant pump in the Gen2 fail between Feb1/2017 -Feb10/2017 as the Priidash logs were showing that the Inverter temp constantly rising after a cold start to over 65C and flashing orange color. No codes were posted yet car was still 'fully functional'
No eddies visible in the tank, touched the pump, it was cold with no slight vibration.
Changed it out today and bled the system I guess it took an hr including having to find a 12mm socket.
Did a 8mi test loop and the Priidash WiFi logs look fine now.
This thread was very helpful along with the lsc aon hv water pump replacement., thanks folks.
ccdisce

 

Just did this job tonight... lots of sharp edges and saw some crusty red stuff I thought might be crusty dried coolant... turns out to be blood from my cut fingers haha.

Process went smoothly. One mounting bolt for the inverter pump sheared off when I removed it (one with the 12mm nut towards front of the car) I guess maybe a little liquid wrench on that nut might be help prior to removal. Bleeding took quite awhile but eventually pump quieted it down and no more air bubbles in the bleeding lines.

 

Thanks to everyone for your inputs into this thread. Patrick, as always, your advice is just great.
I just got the P0A93 yesterday driving home in 105F afternoon Phoenix heat. Managed to get home with no AC and a very concerned wife.... Found this thread and with all your help, I decided that it really was the inverter coolant pump, ordered one last night, picked it up at Camelback Toyota this morning for $98+tax (thank you Amanda for your help) and with very little drama got it installed in less than an hour.
I'd only like to add a few small things:
Of the two fasteners holding the pump's bracket in place, one is a stud that also holds what I believe is the ICE coolant system three way valve in place. One of the mount points for this valve goes over the stud and OVER the mounting flange for the inverter pump bracket. So I had to loosen the three way valve enough to get that one mount point up and over the stud to provide clearance to remove the Inverter pump bracket. I guess I could have replaced only the pump itself, left the old bracket in place, and attached the new pump to the old bracket, but I chose not to do it that way. so this is just a heads up of sorts.
The other thing has to do with refilling the inverter cooling system with coolant. I used an Airlift 550000 vacuum tool to refill the system and was once again amazed at how easy it makes the whole thing go. I originally bought it when I replaced the coolant in the ICE when I replaced the three way valve I just spoke of. "Burping" the ICE coolant system is a real drag and this tool took a multi step, multi hour refilling process and turned it into less than 8 minutes. It's not a cheap tool, about $120 +/- online but really worth it for that particular job. I don't think it's worth it to buy one just for the inverter coolant replacement because "burping" the inverter system is way easier. But if you may be replacing the ICE coolant in the near future and have to do the inverter system also, I really think it's a real time and hassle saver. Well worth the cost.
The savings for replacing the inverter coolant pump yourself are substantial. Dealer wanted $406. I got the pump for around that $100 mark so I saved around $300 for a few hours work. If your numbers are similar, it'll help justify to the wife the cost of the vacuum tool. Makes it almost fun.
Thanks again to everyone,
John

 

I replaced my inverter pump along with other repairs yesterday. I utilized a pair of hose pinchers of the type I used on air cooled Volkswagens. I sourced a new pair at Napa, part 77-4002 in their tool section, photo attached. They're listed at $4.99 online; I may have paid slightly more in store. The pinchers are designed for fuel lines and I will pick up a second pair the next time I work on the one inch coolant lines.

My repairs also included the #3 motor mount under the inverter, for which I removed the coolant line from the inverter to the radiator, then lifted the inverter up and forward but not all the way out to provide sufficient working space. I waited to secure the new inverter coolant pump until the motor mount was replaced and I was reassembling the system.

Once everything was reassembled, I used exactly 2 cups of SLLC to refill and bleed the system. Almost all of the drained coolant came out at the inverter pump, which l assume limited my loss at the coolant line I removed from the inverter. I expect that a second pair of pinchers applied opposite directions would further reduce the loss of coolant to just what is currently in the pump and last few inches of each line.

I replaced all of my cooling system rubber with an engine swap late in the summer of 2015. I wasn't concerned about the pinchers possibly damaging more experienced coolant lines and would consider the age of the lines if I were working on a different Prius.

I utilized the "remove the driver headlight assembly" method in order to provide more working space.

Thank you for the advice and experience offered here. I hope this modification is of use to others performing this maintenance.

 

where's the photo?

 

Wow, those light duty clamps worked eh? good to know, they are compact in size too.

 

They're not quite long enough for a single clamp to fully span the collapsed hose, but a pair applied opposite directions worked well on the inverter to radiator hose that I removed after I connected the inverter pump lines to the new pump. Perhaps because my rubber is relatively new, these pinchers collapsed the lines without any serious effort.

*Added "Perhaps" to final sentence.

 

Just noting that I replaced my faulty inverter pump today with the help of this forum. I didn't undo the rear inverter mount, only the front two bolts allowing an extra inch or so of hand clearance, and I traded a few scraped knuckles for the time it takes to remove the bumper cover and headlamp assy.

All in all, it was a quick job, maybe 35min total. If you have an especially long pair of needle-nose pliers and an +8in socket extension, this makes the job overwhelmingly easier. The most difficult parts of removing the electronics clip, hose clamps, and bottom pump bracket bolt are a breeze with these tools handy.

Thanks for all the help guys.

EDIT: I opted to replace the SLLC rather than clamp the hoses. @Patrick Wong Running the new pump during IG-ON at intervals of 20sec seemed arbitrary. After a few 20s cycles I just left the pump running and bled the valve accordingly while monitoring the coolant level. Any reason for you reported the interval approach to bleeding?

 

Another one bites the dust !!!

Replaced mine yesterday with 169k on the ODO. Previous replacement was the TSB at 68k.