How to Replace the Inverter Coolant Pump

valde3 · Oct 18, 2014

Prius can only be towed with front axle on ground if it’s ig-on and then you should only tow it bellow 67km/h or 42MPH. And if it’s in ig-on then 12V battery will drain. So really only easy and safe way to tow Prius is with (at least) front axle off ground.

JC91006 · Oct 18, 2014

You should ask for a flat bed tow truck when a tow is necessary

fopoku2k2 · Jul 21, 2015

how do I check if my inverter coolant pump is functioning at par??

valde3 · Jul 21, 2015

Open the inverter coolant tank cap and see if surface of the coolant has ripple in it. If it has coolant is circulating and pump is working fine.

fopoku2k2 · Jul 21, 2015

valde3 said: ↑

Open the inverter coolant tank cap and see if surface of the coolant has ripple in it. If it has coolant is circulating and pump is working fine.
Click to expand...

thanks for the swift response. but what do you mean by "if coolant is circulating . . . . "??

valde3 · Jul 21, 2015

fopoku2k2 said: ↑

thanks for the swift response. but what do you mean by "if coolant is circulating . . . . "??
Click to expand...

If surface of coolant in the tank has ripple then coolant is circulating. If coolant is circulating then pump is working fine. Do the check in ig-on or ready.

fopoku2k2 · Jul 21, 2015

valde3 said: ↑

If surface of coolant in the tank has ripple then coolant is circulating. If coolant is circulating then pump is working fine. Do the check in ig-on or ready.
Click to expand...

ooh ok. great thanks. would do it and report back

Erwin Mayrhofer · Jul 26, 2015

Patrick Wong said: ↑

I've noticed that each summer a reasonable number of posters report inverter coolant pump failures. As a result I've recommended that owners consider replacing that pump no later than at 100K miles as a preventive measure.

Taking my own advice, I decided to replace that pump on my 2004 with 81K miles since we are about to move to the very hot southern Arizona area. I'm not interested in having that pump fail in 110 degree F weather, resulting in a potential life-threatening emergency if we are stuck in the desert.

I would rate the pump replacement as an intermediate level DIY project. It is not very easy because access to the pump is tight. You can see the pump if you open the hood and look behind the driver's side headlight assembly.

What you will need:

- G9020-47031 MSRP $116, Net $88 for weborders at Champion Toyota, Houston

- One gallon of Toyota Super Long Life Coolant. You'll end up using 3 quarts or so.

- 10 mm and 12 mm sockets, a good socket wrench and extensions. I found a U-joint was helpful as well as box wrenches in those sizes. You will need a 14 mm open end wrench and a 10 mm box wrench when opening the inverter coolant bleed valve. 24 mm (or 15/16") socket for the transaxle coolant drain plug.

- Drain pan for old coolant

The Toyota repair manual suggests removing both engine under covers to start. There is no reason to remove the RH under cover and the LH under cover doesn't provide much additional access. Hence I did the job working through the hood opening, except when draining the old coolant.

Start by making the Prius IG-ON (not READY) and listen to the sound of the old inverter coolant pump, so that you have an idea of where you need to end up when you are done. You should see turbulence in the inverter coolant container and you should not hear air bubbling in the fluid. Then make the Prius IG-OFF.

Drain the inverter/transaxle coolant by removing the 24 mm hex drain plug at the bottom of the transaxle. Do not confuse with the transaxle ATF fluid drain plug which requires a 10 mm hex key socket to remove. After the old coolant has been drained, tighten the drain plug to 29 ft.-lb.

Remove the black plastic cover over the radiator. Then remove a nut and a bolt that secures a bracket for a water valve located near the pump. The reason that you have to remove the valve is because that bracket is mounted on the same stud, and located on top of the bracket for the inverter coolant pump. Then remove the bolt that secures the back end of the pump.

Disconnect the wiring harness connector. You will need to squeeze the tab on the connector to release it. This is not easy to do.

Remove the two hoses. Note which hose goes to which part of the pump. This is not too easy; I ended up using a flat-blade screwdriver to insert between the hoses and the pump inlet pipe and outlet pipe in order to break up the seal that had formed.

Remove the pump from the car. There is barely enough room to lift the pump up between the radiator hose and the inverter.

Note that the inverter cover has a couple of curves in the leading edge. The curve closest to the LH fender is where I positioned the top spout of the pump while removing it.

Installation of the new pump is the reverse of the removal process. Tightening torque of the hardware is 62 in.-lb. The bolt at the rear of the pump, although needing a 12 mm socket, does not require greater torque since it is also holding down the plastic relay/fuse box.

Fill the coolant reservoir with SLLC, using a plastic funnel to avoid spills. Keep filling until the fluid level stabilizes at the FULL mark. Make the car IG-ON for 20 seconds. As the fluid level drops, replenish to keep the fluid at FULL. Then make the car IG-OFF. Open the bleed valve until you see fluid appear, then close. Repeat the steps in this paragraph until the sound of the pump quiets down, you don't hear air in the system, you see turbulence in the inverter coolant reservoir, and the fluid level no longer drops below FULL.

Take a test drive for a couple of blocks. Then check the fluid level when the car is IG-OFF. Top off as needed so the fluid level is at the FULL mark, make sure the bleed valve is tight, replace the radiator cover, and you are done.

The old antifreeze is poisonous and very harmful to local fauna, pets etc. so please dispose of it responsibly.

The first two photos show the inverter coolant pump outlet hose (forming a reverse S shape) in the middle, and the mounting hardware for the valve bracket immediately to the left and the right of that hose. You can see this is not easy to get to.

The next photo shows the new pump and its part number.

The next photo is blurry and underexposed unfortunately, but shows the location of the old pump. Note that it is in front of the main relay/fuse box (you can see the leading edge of the relay/fuse box where you depress the catch to release the cover) and behind the LH headlamp.

The final photo shows the new and old pumps side by side.

A curious note: I used my Fluke DMM to measure the resistance across the two terminals of the old pump which was still operational. The resistance value was around 1.5 M ohms. When I reversed the ohmmeter leads I got a negative value, so it appears that the pump has more to it than just a simple DC motor - looks like at least an inline diode and a capacitor are involved, who knows what else. I did not measure the resistance of the new pump.
Click to expand...

Erwin Mayrhofer · Jul 26, 2015

Patrick Wong said: ↑

I've noticed that each summer a reasonable number of posters report inverter coolant pump failures. As a result I've recommended that owners consider replacing that pump no later than at 100K miles as a preventive measure.

Taking my own advice, I decided to replace that pump on my 2004 with 81K miles since we are about to move to the very hot southern Arizona area. I'm not interested in having that pump fail in 110 degree F weather, resulting in a potential life-threatening emergency if we are stuck in the desert.

I would rate the pump replacement as an intermediate level DIY project. It is not very easy because access to the pump is tight. You can see the pump if you open the hood and look behind the driver's side headlight assembly.

What you will need:

- G9020-47031 MSRP $116, Net $88 for weborders at Champion Toyota, Houston

- One gallon of Toyota Super Long Life Coolant. You'll end up using 3 quarts or so.

- 10 mm and 12 mm sockets, a good socket wrench and extensions. I found a U-joint was helpful as well as box wrenches in those sizes. You will need a 14 mm open end wrench and a 10 mm box wrench when opening the inverter coolant bleed valve. 24 mm (or 15/16") socket for the transaxle coolant drain plug.

- Drain pan for old coolant

The Toyota repair manual suggests removing both engine under covers to start. There is no reason to remove the RH under cover and the LH under cover doesn't provide much additional access. Hence I did the job working through the hood opening, except when draining the old coolant.

Start by making the Prius IG-ON (not READY) and listen to the sound of the old inverter coolant pump, so that you have an idea of where you need to end up when you are done. You should see turbulence in the inverter coolant container and you should not hear air bubbling in the fluid. Then make the Prius IG-OFF.

Drain the inverter/transaxle coolant by removing the 24 mm hex drain plug at the bottom of the transaxle. Do not confuse with the transaxle ATF fluid drain plug which requires a 10 mm hex key socket to remove. After the old coolant has been drained, tighten the drain plug to 29 ft.-lb.

Remove the black plastic cover over the radiator. Then remove a nut and a bolt that secures a bracket for a water valve located near the pump. The reason that you have to remove the valve is because that bracket is mounted on the same stud, and located on top of the bracket for the inverter coolant pump. Then remove the bolt that secures the back end of the pump.

Disconnect the wiring harness connector. You will need to squeeze the tab on the connector to release it. This is not easy to do.

Remove the two hoses. Note which hose goes to which part of the pump. This is not too easy; I ended up using a flat-blade screwdriver to insert between the hoses and the pump inlet pipe and outlet pipe in order to break up the seal that had formed.

Remove the pump from the car. There is barely enough room to lift the pump up between the radiator hose and the inverter.

Note that the inverter cover has a couple of curves in the leading edge. The curve closest to the LH fender is where I positioned the top spout of the pump while removing it.

Installation of the new pump is the reverse of the removal process. Tightening torque of the hardware is 62 in.-lb. The bolt at the rear of the pump, although needing a 12 mm socket, does not require greater torque since it is also holding down the plastic relay/fuse box.

Fill the coolant reservoir with SLLC, using a plastic funnel to avoid spills. Keep filling until the fluid level stabilizes at the FULL mark. Make the car IG-ON for 20 seconds. As the fluid level drops, replenish to keep the fluid at FULL. Then make the car IG-OFF. Open the bleed valve until you see fluid appear, then close. Repeat the steps in this paragraph until the sound of the pump quiets down, you don't hear air in the system, you see turbulence in the inverter coolant reservoir, and the fluid level no longer drops below FULL.

Take a test drive for a couple of blocks. Then check the fluid level when the car is IG-OFF. Top off as needed so the fluid level is at the FULL mark, make sure the bleed valve is tight, replace the radiator cover, and you are done.

The old antifreeze is poisonous and very harmful to local fauna, pets etc. so please dispose of it responsibly.

The first two photos show the inverter coolant pump outlet hose (forming a reverse S shape) in the middle, and the mounting hardware for the valve bracket immediately to the left and the right of that hose. You can see this is not easy to get to.

The next photo shows the new pump and its part number.

The next photo is blurry and underexposed unfortunately, but shows the location of the old pump. Note that it is in front of the main relay/fuse box (you can see the leading edge of the relay/fuse box where you depress the catch to release the cover) and behind the LH headlamp.

The final photo shows the new and old pumps side by side.

A curious note: I used my Fluke DMM to measure the resistance across the two terminals of the old pump which was still operational. The resistance value was around 1.5 M ohms. When I reversed the ohmmeter leads I got a negative value, so it appears that the pump has more to it than just a simple DC motor - looks like at least an inline diode and a capacitor are involved, who knows what else. I did not measure the resistance of the new pump.
Click to expand...

Erwin Mayrhofer · Jul 26, 2015

Thanks, great help!! Replaced pump, purrs like a kitten, how do you reset the triangular warning light?

Patrick Wong · Jul 26, 2015

Are any warning lights on besides the master warning red triangle light?

Disconnect the 12V battery negative cable where it bolts to the body. While you are there make sure the terminal connections at the battery are tight. Wait a few minutes, then reconnect the negative cable to the body. That should clear any existing DTC (except DTC logged by the skid control ECU and SRS ECU) and then the red triangle light may go off.

If the red triangle light doesn't go off then your car still has a current problem. Start by checking all engine compartment fluids, especially the fluid level in the radiator. Remove the radiator cap to check the level, do not rely on just looking at the fluid level in the translucent plastic overflow tank. Make sure that all doors and the hatch are closed.

tommymommy · Aug 9, 2015

Patrick,

Stupid question - where is the bleeder valve? I have looked and cannot find one on my 2007. I'm sure I'm just overlooking it, but don't want to get into this without knowing. I'm at just under 170k and the last time the pump was changed was under the warranty recall.

Patrick Wong said: ↑

I've noticed that each summer a reasonable number of posters report inverter coolant pump failures. As a result I've recommended that owners consider replacing that pump no later than at 100K miles as a preventive measure.

Taking my own advice, I decided to replace that pump on my 2004 with 81K miles since we are about to move to the very hot southern Arizona area. I'm not interested in having that pump fail in 110 degree F weather, resulting in a potential life-threatening emergency if we are stuck in the desert.

I would rate the pump replacement as an intermediate level DIY project. It is not very easy because access to the pump is tight. You can see the pump if you open the hood and look behind the driver's side headlight assembly.

What you will need:

- G9020-47031 MSRP $116, Net $88 for weborders at Champion Toyota, Houston

- One gallon of Toyota Super Long Life Coolant. You'll end up using 3 quarts or so.

- 10 mm and 12 mm sockets, a good socket wrench and extensions. I found a U-joint was helpful as well as box wrenches in those sizes. You will need a 14 mm open end wrench and a 10 mm box wrench when opening the inverter coolant bleed valve. 24 mm (or 15/16") socket for the transaxle coolant drain plug.

- Drain pan for old coolant

The Toyota repair manual suggests removing both engine under covers to start. There is no reason to remove the RH under cover and the LH under cover doesn't provide much additional access. Hence I did the job working through the hood opening, except when draining the old coolant.

Start by making the Prius IG-ON (not READY) and listen to the sound of the old inverter coolant pump, so that you have an idea of where you need to end up when you are done. You should see turbulence in the inverter coolant container and you should not hear air bubbling in the fluid. Then make the Prius IG-OFF.

Drain the inverter/transaxle coolant by removing the 24 mm hex drain plug at the bottom of the transaxle. Do not confuse with the transaxle ATF fluid drain plug which requires a 10 mm hex key socket to remove. After the old coolant has been drained, tighten the drain plug to 29 ft.-lb.

Remove the black plastic cover over the radiator. Then remove a nut and a bolt that secures a bracket for a water valve located near the pump. The reason that you have to remove the valve is because that bracket is mounted on the same stud, and located on top of the bracket for the inverter coolant pump. Then remove the bolt that secures the back end of the pump.

Disconnect the wiring harness connector. You will need to squeeze the tab on the connector to release it. This is not easy to do.

Remove the two hoses. Note which hose goes to which part of the pump. This is not too easy; I ended up using a flat-blade screwdriver to insert between the hoses and the pump inlet pipe and outlet pipe in order to break up the seal that had formed.

Remove the pump from the car. There is barely enough room to lift the pump up between the radiator hose and the inverter.

Note that the inverter cover has a couple of curves in the leading edge. The curve closest to the LH fender is where I positioned the top spout of the pump while removing it.

Installation of the new pump is the reverse of the removal process. Tightening torque of the hardware is 62 in.-lb. The bolt at the rear of the pump, although needing a 12 mm socket, does not require greater torque since it is also holding down the plastic relay/fuse box.

Fill the coolant reservoir with SLLC, using a plastic funnel to avoid spills. Keep filling until the fluid level stabilizes at the FULL mark. Make the car IG-ON for 20 seconds. As the fluid level drops, replenish to keep the fluid at FULL. Then make the car IG-OFF. Open the bleed valve until you see fluid appear, then close. Repeat the steps in this paragraph until the sound of the pump quiets down, you don't hear air in the system, you see turbulence in the inverter coolant reservoir, and the fluid level no longer drops below FULL.

Take a test drive for a couple of blocks. Then check the fluid level when the car is IG-OFF. Top off as needed so the fluid level is at the FULL mark, make sure the bleed valve is tight, replace the radiator cover, and you are done.

The old antifreeze is poisonous and very harmful to local fauna, pets etc. so please dispose of it responsibly.

The first two photos show the inverter coolant pump outlet hose (forming a reverse S shape) in the middle, and the mounting hardware for the valve bracket immediately to the left and the right of that hose. You can see this is not easy to get to.

The next photo shows the new pump and its part number.

The next photo is blurry and underexposed unfortunately, but shows the location of the old pump. Note that it is in front of the main relay/fuse box (you can see the leading edge of the relay/fuse box where you depress the catch to release the cover) and behind the LH headlamp.

The final photo shows the new and old pumps side by side.

A curious note: I used my Fluke DMM to measure the resistance across the two terminals of the old pump which was still operational. The resistance value was around 1.5 M ohms. When I reversed the ohmmeter leads I got a negative value, so it appears that the pump has more to it than just a simple DC motor - looks like at least an inline diode and a capacitor are involved, who knows what else. I did not measure the resistance of the new pump.
Click to expand...

Patrick Wong · Aug 9, 2015

tommymommy said: ↑

... where is the bleeder valve?
Click to expand...

Remove the large black plastic cover over the radiator, and you will see the bleeder valve in front of the inverter. There is only one valve with 2G (unlike Classic which has two valves and is much harder to purge the inverter coolant system of air.)

tommymommy · Aug 9, 2015

Black tipped nipple?

Patrick Wong · Aug 9, 2015

tommymommy said: ↑

Black tipped nipple?
Click to expand...

Yes, pull off the black rubber cover and then you can attach a clear vinyl hose to the nipple, running the hose up to the reservoir opening.

tommymommy · Aug 9, 2015

Patrick Wong said: ↑

Yes, pull off the black rubber cover and then you can attach a clear vinyl hose to the nipple, running the hose up to the reservoir opening.
Click to expand...

Hand to forehead....I was expecting a stopcock. Thank you, Patrick!

goodMXguy · Apr 22, 2016

I need some help.

I got code DTC P0A93.

Background information= I bought the car online and had already replaced 12 V battery. I knew there was a problem with heat, but it was winter. Now I am getting the same error. the electric cable was disconnected from the inverter coolant pump. As I was trying to find the reason of the problem I connected the cable, and turned the car without pressing the brake. I got fumes,so I turned the car off ASAP. I then realized that the electric was not all the way in so I inserted all the way in this time. I paid attention to see if the pump will come back or if there was any turbulence in the reservoir, but not luck there (no fumes either).

I ordered a new pump and coolant and plan to replace it ASAP. My question is how can I tell this was not a problem of cables?Could the burning fumes did damage the cables? How do I know or go about it IF after I install the new pump nothing comes up?

In the best case scenario the pump was the problem and the car is in shape again, but I just want to be ready.

I got code DTC P0A93

Patrick Wong · Apr 22, 2016

goodMXguy said: ↑

... I got fumes,so I turned the car off ASAP. I then realized that the electric was not all the way in so I inserted all the way in this time. I paid attention to see if the pump will come back or if there was any turbulence in the reservoir, but not luck there (no fumes either).

I ordered a new pump and coolant and plan to replace it ASAP. My question is how can I tell this was not a problem of cables?Could the burning fumes did damage the cables? How do I know or go about it IF after I install the new pump nothing comes up?

In the best case scenario the pump was the problem and the car is in shape again, but I just want to be ready.
Click to expand...

What does "a problem with heat" mean? Does that mean the cabin heater is not working or does that mean you knew the inverter had a tendency to overheat?

What does "fumes" mean? Are you referring to the smell of burnt electronics?

If that is what you mean, the original inverter pump motor has a short. Do not try to plug the connector in, again.

Check the 15A AM2 fuse. It is probably blown. Replace that fuse so that the car can be made READY. You can use a voltmeter to determine the presence of 12V at one pin of the wiring harness connector (another pin should be connected to body ground) which will show you the wiring is OK.

Do not drive the car until the new pump has been installed and the inverter coolant reservoir shows fluid turbulence, which demonstrates that you were able to satisfactorily purge air out of the coolant loop.

goodMXguy · Apr 29, 2016

Hi Patrick.

It's very nice to hear from you. Since I posted I kept driving (I didn't read your response until today). I replaced the inverter pump yesterday. I bleed the air. I hear the new pump working (the old one didn't make any noise). I still don't see any "inverter coolant reservoir fluid turbulence", though. I am not sure how it's supposed to look... Do you think I need to bleed the air again? I did it for about 4 minutes.

Best regards.

Patrick Wong said: ↑

What does "a problem with heat" mean? Does that mean the cabin heater is not working or does that mean you knew the inverter had a tendency to overheat?

What does "fumes" mean? Are you referring to the smell of burnt electronics?

If that is what you mean, the original inverter pump motor has a short. Do not try to plug the connector in, again.

Check the 15A AM2 fuse. It is probably blown. Replace that fuse so that the car can be made READY. You can use a voltmeter to determine the presence of 12V at one pin of the wiring harness connector (another pin should be connected to body ground) which will show you the wiring is OK.

Do not drive the car until the new pump has been installed and the inverter coolant reservoir shows fluid turbulence, which demonstrates that you were able to satisfactorily purge air out of the coolant loop.
Click to expand...

andrewclaus · Apr 29, 2016

Did you use the bleeder valve as mentioned in post 153 above?

Look at the reservoir with a good light while the car is off and have an assistant turn the car to IG-ON while you're looking. You should see the difference in flow. It may be hard to see in poor light or if you don't know what to look for, but you should definitely be able to tell the difference between off and on. Or maybe the system still has air in it. If so, bleed it again with the bleeder valve.

When I did mine, it may have taken quite a few minutes to get every last bubble out. I could hear turbulence in the pump, too, until it was bled completely. You should only be able to barely hear a very quite hum, like an aquarium pump--nothing else.

How to Replace the Inverter Coolant Pump

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