Lots of warning lights after 3-5 hours driving

I think that the root cause of your problem is a defective inverter coolant pump, since your problem only happens on a long trip. After the inverter overheats, DTC P0A93 "Inverter Cooling System Performance" is logged. Overheating causes the DC to DC converter to fail, so when the voltage on the 12V bus droops, that causes the various warning lights to come on and the other DTC to be logged. This problem has been frequently reported especially in the summer.

If you make the car IG-ON (from IG-OFF, press the POWER button twice without depressing the brake pedal, so that all the instrument panel warning lights come on) and then open the hood, place your head near the driver's side headlight and see if you can hear the inverter coolant pump running. Also look for turbulence in the inverter coolant reservoir container (which would indicate the pump is running.) You probably won't hear the pump running or see coolant flowing in the container, and if you have the pump replaced this should solve your problem.

Good luck.

 

so let me get this straight. you can pull the car over, restart 3x, and the codes will go away and then you are on your jolly way. and it takes 3-5 hours of driving for this condition to appear. it's uncommon for that kind of driving to be required before the inverter overheat pops up, unless maybe you're in a pretty cool climate.

have you checked the inverter coolant level?

did you pull over right away?

 

elally, based on the feedback you are getting from that particular Toyota shop, I wish you would find another one to work with. Sending you on another long drive is not good diagnostics.

 

Hi All,

It could be an intermitant failure of the inverter cooling pump. After several hours of operation, its bearings get warm and the pump seizes or slows.

This happened to my Ford Tempo gas-tank located fuel pump. With the other problems on the car, took a long time to finally confirm that was the problem and pull the tank. But after that it was only the Alternator failing (which happened a few times) would stop it. The Ford dealarship mechanics I took the car too completely flubbed the diagnosis, even after I told them what it was after months of casual investigation had narrowed it down.

As the inverter coolant pump is a recognized problem with the 2006's and before Prius Gen II's, I say replace it. There is a service bulletin indicating its a common failure and it should be under warranty if the car has less than 60 K miles on it.

 

P0571 is interesting, because it's a failure of the brake light switch. The switch is a two-pole switch - both poles are connected to +12V, through different paths, so one pole should always be at +12V and the other disconnected, except for a very brief cross-over period. The code is logged when both are below 1V (effectively disconnected) for more than 0.5 seconds. To me, if the brake light switch is actually working (the brake light comes on), that would suggest some sort of ground fault, that one or more ground point connections in the car is bad. That means the computers can't accurately assess the values of the various sensors, and communications between each other.

The diagnostic for P0607 is even more straightforward: clear the code, check if it's still output, if so, replace HV ECU. The ECU contains two CPUs which both read the brake light switch signal (STP) and this code is logged if the two CPUs think it has a different value. The HV ECU does appear to have two different grounding connections, which could possibly lead to the different CPUs, but they eventually end up at the same real ground point. It does go through a couple of connectors before reaching the chassis ground point, though.

The other codes could be equally spurious. P0A37 is 'generator temperature sensor circuit range/performance'. I can't see how P0A93 is tested, but would assume that it's one of the myriad connections between HV ECU and inverter. (Probably MIVT for MG2's inverter's temperature, GIVT for MG1's inverter's temperature, CT for the DC/DC converter's temperature.)

U0100 indicates lost communication between the HV ECU and engine ECU (ECM). Given these two units are strapped back-to-back, there shouldn't be any reason for this to happen. U0111 is bad communication between HV ECU and battery ECU. Again, if the ground is floating (probably intermittently) then the voltage sent by the other ECU can be sensed incorrectly.

I'd check the ground connection on the HV ECU and if that seems to be OK, swap out the HV ECU.

 

I agree with Patrick. I think when the Inverter crow bars it probably throws every code it can.

BTW, based on so many people complaining of this pump failure I installed an inverter temp alarm test kit on my 2007 that monitors inverter temperature. Basically used my 2007 as a test bed.

It only alarms when slight over temp of the inverter has been reached signaling pump failure. It consists of a thermostat mounted to the Inverter case:

STC-120


that shorts its leads together when the case of the Inverter reaches a temp of 113F. 12 volts goes into one lead and the other lead of the thermostat is wired to a 12 volt car alarm horn which is grounded. It works real good. If Inverter temp goes over 113F the car alarm horn goes off. I installed an inline fuse holder so the horn can be disconnected quickly upon activation.

This kit can also discover an intermittent pump too which you could possibly have.

Total cost was around $20 delivered for everything and took me about an hour to install. I recommend this kit for older Prius's because if you burn up your inverter out of warranty your looking at alot of money $2-4K not to mention if it causes a dead boot battery and you need a jump exposing your car to rookie jump starts which can total an older car and on this site we have seen many many disasters. Remember there is no dash board alarm when the Inverter cooling pump fails. It only alarms when the Inverter severely overheats and also fails to output its running voltage to system and motors which is why when it starts to overheat it begins failing and it is described as gradual loss of locomotive power and most people not knowing how bad the problem is continue to drive which only exacerbates the issue and exposes the Inverter to complete overheat and total failure. My personal suspicion is this event low or wrong run voltage to the electric motor is not good for the MG windings either.

Short of the Transaxle & motor the Inverter plus installation is the most expensive part of our car.

The Thermostat can be bought at Mouser for $5 with no minimum order and I got the horn new off ebay $15 delivered.

Please PM me if you need additional info. Good Luck.

 

Damn good idea. I'm going to make one too

 

I'd take them up on their offer, sounds fair to just pay for the pump.

 

well, that's not the typical failure mode for the inverter coolant pump, but if they're throwing in free labor...

make sure to check coolant levels when you get the car back.

it's unusual for an overheated prius to start right up and go again, and if you pulled over right away and it actually was an overheat, it probably did not overheat to the point of harming the dc-dc converter. the symptoms aren't all accounted for, but by all means if you get a deal, try the new pump and see what happens. we're not entirely convinced it will solve the problem, but only another long drive will tell.

 

The coolant heat recovery pump is the one that makes noise upon startup and shutdown. This is not the same as the inverter coolant pump.

Since you say that you can hear the inverter coolant pump running and you can see turbulence in the inverter coolant reservoir, it's not obvious that pump is causing your car's problems. Now, it could be that after several hours the pump stops working or pumps at a slower-than-normal rate, causing the problems that you noted.

What is weird is that after the warning lights appear and you turn the car off, you say that you can restart without difficulty or delay. If the inverter really was overheated, you should have to wait a while for that part to cool down before the car would start to function again.

I am not confident that if you have the inverter coolant pump replaced, that this will definitely cure your problem. However, I can't offer a better idea at this time, unless you are willing to do as the dealer says, and drive the car on another long trip to attempt to induce a failure. When that happens then you could see whether the pump is still running or not.

It is true that the inverter coolant pump is a common failure point, and if you replace that part then you can rule that out as the cause of your car's problems. Then, if the trouble recurs, the likely cause would be the transaxle, the inverter itself, or maybe the traction battery. The latter two would be covered under the hybrid system warranty but the transaxle would not be.

 

Thanks dude

 

If I may make a suggestion. Go to Sears and pick up an IR Thermometer. They have pretty good ones there for about $30
last time I looked. I got a Sears IR off eBay for $10. Not sure if Home D sells them. Fluke makes the best but pricey. I take mine in my laptop case everywhere I go.
Very handy thing to own.

Anyway next time it throws codes pull over...leave car running and check the temp of the inverter box itself and maybe even the coolant tank next to it. Should be very cool in cold weather. Much less than 90 F everywhere. My 07 Inv. never hit more than 95F in dead of Florida summer.Also see if there is turbulence in plastic coolant can next to the Inverter.

But really if you can afford it replacement of the pump even if its not
the cause is not a bad idea....especially if your trying to hit that elusive 400,000 mile mark. But first figure out whats up with this event as this might be expensive too.

BTW, what's the state of tune on this car? How often is the oil changed and the transmission fluid changed please? Has the coolant for rad & Inverter ever been changed. You might have just really gnarly coolant.

 

This brings up some interesting mental images. I can just see edthefox5 at the singles bar with his trusty IR thermometer, pointing it at women's...ahhh, well, "certain parts" to see if they are receptive dates. One with laser targeting would be good in this case.

It's always good to have your IR thermometer close at hand.

Tom

 

If it was a singles bar for engineers, of *course* that would work. Even better would be a pricey FLIR camera, which I use to perform infrared thermography on transformers and other electrical equipment

"My, what a large infrared thermographer you have. Want to go back to my place and do some transforms?"

 

Some of those infrared cameras are great. I look at them in the catalogs and lust. Mind you, I don't really need a $14,000 camera for anything, but I still want one.

Tom

 

Failure of the coolant heat recovery pump will not produce the symptoms that you noted in your OP. However if you want to have it replaced as a preventive move, that's up to you.

Yes, a competent mechanic who is willing to make an effort to learn about the two Prius cooling systems could certainly do the work. However, a mechanic who is not willing to invest that time should not be asked to do this job since it is easy to screw up the cooling systems (especially the engine coolant system) if the air is not purged out.

Further, if you start to involve an independent now, then in the event that you still have warning lights appear after the two pumps are replaced (which I think is fairly likely) then the dealer service dept will question whether the independent did the job right, and want to redo some of the labor, etc.