inverter testing and replacement

I strongly suggest that you either purchase the Toyota paper repair manuals for your vehicle (which are available by ordering through your dealer's parts dept), or invest some money and time downloading appropriate repair manual files at the techinfo.toyota.com subscription website.

The inverter pump runs constantly when the car is IG-ON or READY. The easiest way to test the pump is to listen for it running. It is located near the driver's side headlight assembly. If the pump is removed, apply 12VDC to the terminals for a brief period of time (since no fluid is in the system, we don't want to overheat the pump), to confirm that the motor is running.

Regarding the inverter, evidence that it has failed is provided when appropriate DTC are logged by the hybrid vehicle ECU. Other than checking for high voltage leaks to ground, I do not believe that there are any other tests that the repair manual suggests for the inverter. The inverter is not a field-repairable assembly; the repair philosophy is a whole-unit swap.

 

Other non-toyota links to consider include:
The set of ORNL reports that came out in ~2005. Be careful with these, It appears that they might have reversed the polarities on some parts. But hey, your tax dollars paid for them, might as well take advantage of their research!

EE times also did a teardown awhile back. (I only have a paper copy, but they did it at Embedded systems conference in ~2006)

Hobbit's page has some excellent teardown info.

I'm probably missing a whole bunch of other sites.. But those are some unofficial, but _highly_ trusted ones. I highly recommend the toyota service manual, as this has the 'official' stuff...

 

Am curious as to why you are asking how to check the inverter. Isn't it part of the hybrid system and therefore covered under the 8 yr/100,000 mi warranty? if so why don't you have the dealer check for you. I am a new prius owner and am learning the high price tag of do it your self jobs on these cars.......take a look at my thread in this Technic. Discuss.........."I blew up my inverter"......also if you find that your inverter did go bad I would like to know as I have been lead to believe they don't go bad....we just blow them up..................please let me know what you find out by posting on my thread or here....I will watch to see what info you get....thanks Ginny

 

His Prius is an 2003 as is mine. I passed through 100,000 miles just at the end of last year. I have no further warranty coverage (and am kinda glad about it.)

Bob Wilson

 

PATRICK: need to get educated on this part too. What would be the symptom if there was a high voltage leak to ground? Would the car stall or quit running. Thought the only way the inverter went bad was if jumped with wrong polarity??????
Thanks, Ginny
from "I killed my inverter???"

 

Hi Ginny,

The Prius inverter will occasionally fail. Usually this is because the inverter coolant pump stops running which causes the electronics to overheat. Most of the time, once a new pump is installed, all is well. However on occasion the inverter will be fried as a result of overheating. By and large, I would say that Toyota is unusually generous in covering such incidents under the hybrid system warranty.

The Prius high voltage system is set up so that neither the negative or positive side is grounded for safety reasons. The battery ECU will monitor the status of the high voltage line and generate DTC P0AA6 if it detects any leakage to ground.

The DTC will not prevent the car from running when it first appears. However once the car is shut down, it will refuse to restart. When the DTC is logged, the master warning light and hybrid vehicle icon should turn on.

 

Hi Ginny,

Yes, it is a safety thing. The battery high voltage and inverter outputs that drive MG1 and MG2 have a 'ground fault' detection circuit and if it ever falls below 10 megaohms, it not only throws an error code and master alarm, it shuts down the whole high voltage system. The error code is "P3009" in the NHW11 models.

This is a safety feature so if the battery power cables that run under the car; a water or electrolyte leak; or anything else compromise the high voltage systems, the car fails rather than risk human life. We can always replace a car.

Bob Wilson

 

Hi Bob,

I know of a Yahoo poster who continued to drive her Classic although DTC P3009 appeared.

With 2G, the equivalent DTC is P0AA6. When this DTC appears, the car can continue to be driven; however once it is IG-OFF, then it will refuse to restart.

 

Wow! Another reason to prefer the G1! <grins>

Owch!

Bob Wilson

 

my 2001 prius had a inverter pump problem, although it would pump it wouldnt be at a fast enough rate to cool the inverter down, so i would get that big triangle.

i decided to check it by putting my hand on it, and listening for a rushing of water sound , and a motor type sound. since none of those emanated from the pump i replaced it. And WHAT A DIFFERENCE

i figured out it wwas the inverter, because when i was driving the diagnostic screen on the MFD showed 10.9 volts, this was while i was driving at about 55 mph, I had to pull over and shut it down, i eventually poured a cup of ice i had left over from coke a cola from sams club, and i waited in the 94 degree summer heat for about 10 minutes, started it up erased codes and was able to drive another 10 miles until the inverter overheated again ( due to the fact i stopped at a light and had A/C on ). Since the frequency of the triangle kept going faster and faster everytime i waited and cleared the codes with my scanner, i decided to drive it all the way home, on bare 12 volt power, luckily a rainstorm started and suddenly my dashboard became bright again, and i made it home safely.

again this was because my prius was a salvage vehicle that was fixed up, i drove it about 20,000 miles since it was fixed up until this problem occured, i opened the inverter pump ( kinda like scratched this thick rubber coating off one side ) and there was a circuit board inside, then i decided to buy a new pump on ebay for 50 bucks.


so far for my 05 prius the coolant pump has not failed, and i believe it shouldnt fail since it did not get damaged in the collision.

 

Patrick Wong already addressed your questions about the inverter and cooler.

Yes, you can download everything you need during the daily fee. Just make sure you get everything you need!

 

I first suggest that you reset the codes by disconnecting the negative battery terminal for 10 minutes, reconnect, then go for a short drive and see if the car works without codes appearing immediately. If it does work, then you know that the inverter and transaxle should be good and that the problem is likely due to overheating caused by a bad inverter coolant pump.

You should be able to hear the inverter coolant pump whenever the car is IG-ON (not READY) as well as when the car is READY and the ICE is not running. The pump should sound like an aquarium pump and you should not hear any air. The coolant container should have a step in the level, where the front is higher than the rest of the fluid.

By P130, I suppose you mean DTC P3130 Inverter Cooling System Malfunction. Either the coolant pump or the electric cooling fan are suspects. Usually the coolant pump is the problem.

DTC P3125 Converter & Inverter Assembly Malfunction - your plan to replace the coolant pump first is a good plan. If you find that the inverter is bad, it appears that you can get a salvage part for ~$300 on eBay.

I paid $50 for the techinfo monthly access so that I could download everything I needed. If you just want to pay $10 and sign up on a Friday, you may be able to maintain your access until the following Monday. It is a PITA to deal with that website but the repair manual info is excellent.

Bleeding air out of the inverter coolant system is a tiresome process, allow 3-4 hours for that the first time you try to do it. You must continue until you no longer hear air in the system and you should be able to see the step in the fluid.

The attached photo shows how the fluid step should appear. This assumes that the fluid level is full when the car is IG-OFF.

2G is the reverse where the higher step is at the rear of the container.

 

Everything Patrick said plus you may want to flush the inverter coolant loop lines. Good Prius friend Hobbit has discovered the coolant can form a jelly-like material in the pipes. This could easily cause the pump and coolant loop to fail. So far, we don't have a good diagnosis of what causes this coolant 'jell' to form. However, aluminum salts are suspected.

Bob Wilson

 

OK, this is very interesting. Can you pls describe what the error icon looks like? Is it the vehicle outline with an ! point, or the battery icon, or the PS (power steering) icon?

If you reset the codes by disconnecting the negative terminal of the 12V auxiliary battery, waiting 10 minutes, then reconnecting the terminal; then started the car when the drivetrain was cold, and immediately a warning icon appeared, then it sounds like the inverter coolant pump is not the immediate problem (although it could be a contributing factor).

Do you have access to a digital voltmeter? It would really help if you could measure the voltage across the 12V battery when the car is READY. If it is showing ~13.8V, then the DC to DC converter (which is part of the inverter) is probably working OK, at least while you are doing the measurement. If it is showing a significantly lower voltage, this would help confirm that the inverter must be replaced.

With the engine running all the time and poor throttle response, I am wondering if your traction battery is dead. I realize that your dealer did not report any DTC associated with the traction battery (for example, DTC P3006 "Battery SOC Are Uneven"); however that failure could be consistent with your latest reported symptoms. Now that you can see the MFD screens, how does the traction battery SOC gauge behave? Normally the Classic gauge will either show 50% or 75%. If it shows other readings, especially if the readings change quickly up and down, that is evidence that the traction battery is dead.

Another explanation for lagging throttle response is that the accelerator pedal assembly might be bad; however this should produce DTC P1120 "Accelerator Pedal Position Sensor Circuit Malfunction". If you suspect the pedal assembly is bad, try repeatedly depressing the pedal around 30-40 times when the car is IG-OFF, in an effort to clean the two potentiometers that track the position of the pedal. If the poor throttle response problem goes away, then you know the pedal assembly must be replaced.

 

Bad accelerator pedals don't always throw the P1120, oddly enough. If this is suspected as a contributing factor, the only simple way is to swap in another one from a known-good car. Maybe someone in your town will play along? The swapping only requires a 10 mm socket, 6" extender, and some upper-body flexibility.

Toyota marks up the accel pedal assemblies pretty high, so if one is needed see if our Bob Wilson has one. Or you could DIY? Easy work, except for the fact that there is no allowance for mistakes.

 

Hello Pat, You always have great answers! So, Where is the inverter, what is it's physical size, is it a stand alone box, what is its output voltage and frequency and last can it's output be seen on a OScope with only 12VDC feeding it ( on a bench). ty