P0A93 - Inverter Cooling Performance

[grantwils]

Anyone got any hints or tips to diagnose this issue on a 2009 GS450h with 130k on the clock?

 

Comes up after around 15 minutes driving.

 

Clears after 12v Battery removed. Doesn’t come on if you drove sub 15 minute journeys.

 

 

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[Farqui]

What is the coolant level on the hybrid cooling reservoir ?

Has the hybrid coolant been changed recently ?

Any coolant leaks ?

[Britprius]

3 hours ago, grantwils said:

 

Anyone got any hints or tips to diagnose this issue on a 2009 GS450h with 130k on the clock?

 

Comes up after around 15 minutes driving.

 

Clears after 12v battery removed. Doesn’t come on if you drove sub 15 minute journeys.

 

 

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This is almost certain to be failure of the electrically driven coolant pump for the drive inverter, and the transmission cooling. The inverter rises in temperature, and if it goes above a given level this fault code will be given. As Lee has already said check the coolant level for the inverter, and if this is ok I would strongly advise against driving the car except perhaps for a short distance from cold to a dealer.
If the inverter or transmission fails through over heating your talking of several thousands in damage for a comparatively cheap pump.

John.

[grantwils]

Thanks guys.

Plenty coolant in the reservoir I can see, not sure if it’s engine or inverter coolant.

How easy is the pump to change? Is it an eBay and DIY job or a Lexus main dealer thing?

Any easy way to diagnose? I’ve got an OBD reader if that’s any use. Or can I test the pump in place or on a work bench?

It had a main dealer service at 110k but local garage did basics since then, just oil and filter stuff.

Have been meaning to get the hybrid system checked to get the warranty but haven’t been in yet. I’m not sure if coolant pump would be covered.

The ‘almost certainly’ wording inspires confidence. Thanks!


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[Herbie]

18 minutes ago, grantwils said:

Any easy way to diagnose? I’ve got an OBD reader if that’s any use. Or can I test the pump in place or on a work bench?

Given that P0A93 is already an OBD code I don't think your OBD reader will give you much more than it already has.

It's an electric pump so you'll need a multimeter at the very least to do any diagnostics. Cheapo ones can be had for under a tenner but it's worth spending a bit more. I've got one of these and it's excellent - very accurate and very versatile.

[Britprius]

The coolant pump is not difficult to change just two hoses one electrical connector, and mounting bolts.

Clamp the hoses close to the pump to save loosing coolant, and having to bleed air out of the system afterwards. Use only Toyota SLLC  (Supper long life coolant) for topping up. Although the same coolant is used in the engine the inverter is a completely separate system. Your handbook should show where it is.

It may be worth checking if there was a recall for the coolant pump on the RX, and if so has yours been changed. I know a number of Toyota hybrids had a recall for this including the Prius. There was no age or millage restrictions on the recall.

The pump is a sealed unit, and from memory is a 3 phase unit meaning you cannot just connect it to 12 volts.

John.

[royoftherovers]

3 minutes ago, Britprius said:

The coolant pump is not difficult to change just two hoses one electrical connector, and mounting bolts.

Clamp the hoses close to the pump to save loosing coolant, and having to bleed air out of the system afterwards. Use only Toyota SLLC  (Supper long life coolant) for topping up. Although the same coolant is used in the engine the inverter is a completely separate system. Your handbook should show where it is.

It may be worth checking if there was a recall for the coolant pump on the RX, and if so has yours been changed. I know a number of Toyota hybrids had a recall for this including the Prius. There was no age or millage restrictions on the recall.

The pump is a sealed unit, and from memory is a 3 phase unit meaning you cannot just connect it to 12 volts.

John.

Does this help anyone, or I am just confusing the issue?

 

 

[Britprius]

Hi John.
Different pump. The pump you have linked is for the hydraulic oil in the transmission. The OP's code is for the coolant that runs around the transmission, and the inverter.

John

[royoftherovers]

41 minutes ago, Britprius said:

Hi John.
Different pump. The pump you have linked is for the hydraulic oil in the transmission. The OP's code is for the coolant that runs around the transmission, and the inverter.

John

Thanks John.

Engineering, Technical Drawing, Metalwork and Woodwork were not any of my strengths !!

Mind you I could tell anyone my Times Tables and boy I could spell !!

[grantwils]

Thanks guys.

Does anyone have a diagram or drawing of the pump?

Tracing the pipes, I’m assuming pump is in the scary looking box with orange cables and a cover saying ‘this isn’t a Battery you tit, it’s in the boot. Stay away from this scary high voltage thing if you don’t know what you’re doing’ or words to that effect.

The coolant reservoir seems to be linked in my GS for engine and inverter coolant.

My OBD reader tells me temperature data but I think it’s just for engine coolant rather than anything else.






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[Britprius]

The white container with the red fluid in it is the inverter coolant. The box with the orange high voltage cables going to it is the inverter. It is cooled by coolant flowing through an aluminium panel on it's underside. The coolant also goes to a heat exchanger built into the transmission. 
The inverter coolant circuit is not connected to the engine coolant in any way. You should see slight turbulence in the coolant liquid through the filler neck with the car in ready mode.
Having checked online as I suspected there is a recall for the RX350 coolant pump so contact your dealer to see if yours has been done. It could be replaced free of charge.

It is most unlikely your code reader will read the full Toyota/Lexus list of ECU codes. The ECU you are looking for is the "hybrid control ECU"

John.  

[Britprius]

4 hours ago, royoftherovers said:

Thanks John.

Engineering, Technical Drawing, Metalwork and Woodwork were not any of my strengths !!

Mind you I could tell anyone my Times Tables and boy I could spell !!

Science maths technical drawing, and metalwork were good for me, but English, and History were way over my head. However we are not all the same a good thing giving us a diversity of skills. It's just a pity that all skills are not treated equally when it comes to pay. I am in no way putting down there skills, but the pay of some football players is just plane crazy.

John.

[royoftherovers]

35 minutes ago, Britprius said:

Science maths technical drawing, and metalwork were good for me, but English, and History were way over my head. However we are not all the same a good thing giving us a diversity of skills. It's just a pity that all skills are not treated equally when it comes to pay. I am in no way putting down there skills, but the pay of some football players is just plane crazy.

John.

As regards the pay given to footballers, I couldn`t agree more, John.

In a Capitalist world however there exists the  law of supply and demand, so goods have different prices as does labour.

Let`s stick to motoring matters!

[grantwils]

Does anyone have any drawings of the cooling system or a how to for swapping the pump?

Out of curiosity, where’s the cooling reservoir for my engine if this is just for the inverter cooling system?


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[Britprius]

The container with the black cap at the bottom left of your picture is the engine coolant reservoir.

Have you checked on the recall situation?

Do a search on line there is lots of information on these pumps along with pictures, and fitting information.

John.

[Lwerewolf]

The part is G9040-30010.

You can access it from underneath, just take all the covers off. It's the thing with the small finned radiators on it.. also, two pipes (one vertical, one horizontal) & a connector.

https://www.google.com/search?q=G9040-30010&tbm=isch

Even if you keep the hoses shut, a small amount of coolant will leak, and you'll have to add coolant & bleed the system as well as you can. You might get away with just adding coolant with the cap off & the pump running. The proper way involves running the pump and bleeding the system with the bleed ports.

I remember there being two inverter bleed plugs, but that's on LHD cars (mine). The inverter loop radiator (in front of the main radiator, at the top, G9010-30010 ) appears to be the same, so there should be an attachment for a hose & a hex screw to loosen there (top-left, should be easy to spot).

The pump runs at all times when the car is in "ready" mode (a.k.a. turned on, might take 20-30sec). You can also force it to run via techstream diagnostics while on 12v power (double press the power button without having your foot on the brake pedal). Techstream should be the better way - engine won't start, so you don't have to worry about heat, vibration and etc. from anything other than the pump.

Check for turbulence, check the INV W/P fuse, squeeze the hoses around the pump (there might be blockage). You can check the wiring harness & try running the pump directly from the ECU, but I wouldn't do that without having access to the wiring diagrams, service manual and the particular page about the p0a93 DTC... better safe than sorry when the wiring harness alone costs >1k gbp, nevermind the ECUs and anything else that you might fry if you start assuming things (ok I might be over-exaggerating but safety first).

[grantwils]

Check for turbulence, check the INV W/P fuse,

Thanks for the help so far folks.

Some progress today following the advice above... Its eating 10AMP inverter water pump fuses within seconds.



I’m still looking for an image or diagram of the location of the inverter cooling pump if anyone can point me in the general direction of one?

I suspect pump is jammed.


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[Lwerewolf]

Look underneath the car, remove the cover that's usually removed for oil changes. It has a finned radiator on it, two water hoses and an electrical connector. Fairly obvious to spot. Let's hope it's just blocked and not shorted...

 

[Britprius]

On 9/6/2019 at 5:06 PM, grantwils said:

 

Thanks for the help so far folks.

Some progress today following the advice above... Its eating 10AMP inverter water pump fuses within seconds.



I’m still looking for an image or diagram of the location of the inverter cooling pump if anyone can point me in the general direction of one?

I suspect pump is jammed.


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It is unlikely the pump is jammed, and this in it's self due to the design of the motor would not necessarily blow the fuse. The pump recall was because it was found in manufacture the three phase winding's for the pump motor were being scratched "the formal coating insulation on the winding's was damaged" this eventually cases the winding's to short circuit causing the fuse to blow. Exactly your symptoms. 

The winding's are in a separate housing with no moving parts to the magnetic armature or rotor that is formed as part of the pump impeller running in the coolant. The impeller runs on a fixed shaft with a carbon bearing lubricated by the coolant .

John.

[grantwils]

It is unlikely the pump is jammed, and this in it's self due to the design of the motor would not necessarily blow the fuse. The pump recall was because it was found in manufacture the three phase winding's for the pump motor were being scratched "the formal coating insulation on the winding's was damaged" this eventually cases the winding's to short circuit causing the fuse to blow. Exactly your symptoms. 
The winding's are in a separate housing with no moving parts to the magnetic armature or rotor that is formed as part of the pump impeller running in the coolant. The impeller runs on a fixed shaft with a carbon bearing lubricated by the coolant .
John.

Sounds like you know what you’re talking about. So new pump required you think?

There’s apparently no outstanding recall for my car. Should there be?


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[Herbie]

7 minutes ago, grantwils said:

So new pump required you think?

Not necessarily. 

That fault code indicates that the inverter water pump isn't working (and a lack of turbulence in the coolant reservoir when the car is on would confirm this) but pump jam isn't the only thing that could go wrong.

It may be a problem with the wiring or connections to the pump. If you feel safe, know what you're doing, and got the necessary safety equipment, ie, a pair of insulating rubber gloves/gauntlets rated to 1,000V, you could check the voltage at the pump connector. I'm not sure what voltage should be present but all three phases should be the same.

I'll see if I can find any documentation regarding what voltage the pump requires.

[Britprius]

There should be evidence on the Lexus "My car web site" or at any dealers to show the pump has already been changed once. After that any further work is at your expense. It is virtually certain a new pump is required. It is possible for a faulty pump to damage the drive ECU, but that is unusual.

John.

[Britprius]

14 minutes ago, Herbie said:

Not necessarily. 

That fault code indicates that the inverter water pump isn't working (and a lack of turbulence in the coolant reservoir when the car is on would confirm this) but pump jam isn't the only thing that could go wrong.

It may be a problem with the wiring or connections to the pump. If you feel safe, know what you're doing, and got the necessary safety equipment, ie, a pair of insulating rubber gloves/gauntlets rated to 1,000V, you could check the voltage at the pump connector. I'm not sure what voltage should be present but all three phases should be the same.

I'll see if I can find any documentation regarding what voltage the pump requires.

The voltage at the pump is only 12 volts ac when running, However if the motor is disconnected or faulty I believe there will be no reading as the motor uses hall effect transistors to give feedback to the ecu for rotor position, speed, and direction of rotation. Without this information I believe the ECU shuts down. I could be wrong on this, but this is the usual setup for this type of system.
The HV Battery cooling fan runs on the same system, but uses input from the HV Battery ECU to control it's speed although on that motor the control ECU that converts the 12 volts dc to 12 volts three phase ac is built into the motor. The ac frequency is controlled by the HV Battery ECU to give speed changes.

John.

[Herbie]

Thanks for that John. You know far more about this than I do so I'm not questioning you but....
 

45 minutes ago, Britprius said:

the motor uses hall effect transistors to give feedback to the ecu for rotor position, speed, and direction of rotation.

why would this information be needed by the ECU?

I can see that the ECU needs to know the speed of the pump, but rotor position and direction? It's only pumping water around a sealed system so it wouldn't matter what direction the water was moving in, it would still pick up heat and move it to the rad.

[Britprius]

Because the pump is a centrifugal pump with the outlet set at a tangent to the rotor direction is critical to the performance of the pump. The rotor position is needed to get the optimum switching timing for electrical efficiency. These so called digital motors are very efficient compared to both brush, and squirrel cage motors offering more torque, and speed at less current.
They do not work with fixed frequency, but ramp up when starting to remove the current spike associated with motor starting, and give better torque.

John.