Mysterious shutdown this weekend

Four items for your consideration:

1. Was the inverter coolant pump replaced under the limited service campaign yet? If not that should be done now.

2. Check the inverter coolant reservoir, looking for fluid turbulence within, when the Prius is READY. If you don't see this then the pump is not running and you should immediately have that replaced.

3. Have you driven more than 15 miles at a time, since your weekend failure? If yes, what was the duration and average speed of your longest drive?

4. Regarding the lack of drivetrain codes, I am wondering whether your 12V battery is marginal which caused the engine and hybrid vehicle ECUs to lose their memory of stored DTC. Has the battery been replaced yet?

 

I was thinking the same thing Patrick. Especially if the inverter got hot enough to disable the DC-DC converter, which it probably would have.

 

That all sounds very much like the inverter coolant pump failure on mine, as Patrick suggested. That should be investigated and if necessary repaired immediately, to prevent possible damage to the very-expensive inverter.

But do also check the 12V battery as one simple possibility that should be eliminated:
http://priuschat.com/forums/newbie-forum/73400-weird-stuff-happening-mpgs-dropping-test-battery.html
(If you have any questions or comments specifically about that thread or the procedure please reply in that thread.)

 

Is the 12V battery the original one? If you have a Scangauge, you can watch voltage during shutdown to see how far the coolant heat transfer pump pulls it down.

 

Pls check the inverter reservoir when the car is READY to see if fluid turbulence exists, as I suggested above. That is a really easy thing to check.

Further, the battery voltage check is not reliable unless you do the check first thing in the morning after the car has sat undisturbed overnight, prior to making the car READY.

I offer a scenario below which would explain all of the symptoms that you provided above:

Assume that:

- The inverter coolant pump failed, or was incorrectly installed so that air remains in the system; and

- The 12V battery is in marginal condition and will not offer a safety reserve.

Please note that the inverter will not overheat until you drive a substantial distance, which depends upon ambient temperatures.

Now, you go for your 15 mile drive. The weather is sufficiently warm so that the inverter finally overheats as we assumed the pump is not doing its job. At that point, the DC/DC converter within the inverter shuts down and voltage on the 12V bus starts dropping below the nominal 13.8VDC.

Now the 12V battery must bear the load. However since we assume your battery is in marginal condition, it cannot do so. This causes the 12V bus voltage to sag to the point where the various ECUs shut down. Hence the power steering and brakes do not operate. In addition, the engine and hybrid vehicle ECUs will lose whatever DTC had been logged.

The skid control ECU is highly sensitive to 12V power since it depends upon that for proper functioning. It will turn on the VSC, ABS and ((!)) brake warning lights. That ECU, unlike the others, will retain DTC even when 12V power is lost.


It has been proven through many prior posts that the Toyota dealer equipment is incapable of correctly testing the Prius 12V battery. You'd think that would be a really simple thing to do; however many false reports of "battery OK" have been received.

You can easily prove or disprove my hypothesis by checking the inverter pump operation.

 

Thanks for posting the results of your tests. We now know the inverter coolant pump is not an issue.

Yes, if the DC/DC converter within the inverter were to shut down, you would not see a warning specific to that. The warning would appear when the systems which rely upon 12V power notice the reduced voltage and start to complain.

Unfortunately your voltage reading (above 10V, below 12.5V) is not sufficiently precise to say much about the battery's condition. If it was 10.1V then it definitely needs to be replaced now. If it was 12.4V then it would be OK.

If your measurement cannot be more precise, then since a question remains about the 12V battery's condition I would recommend replacing it now.

Perhaps you might take a nice long drive (30 miles or more) today and see what happens? Good luck.

 

Hi S,

A drop to 10 volts with the lights on, from 12.5 volts sounds like allot to me. Which indicates allot of resistance between the battery and the jump-start terminals (and probably the lights). Have the battery attachments (battery is in the right rear of the car) checked to be tight, and not corroded first. Clean them if they look the least bit dirty.

To see if this problem is fixed, and not the battery, compare the battery voltage at the battery posts, to the voltage at the jump-start terminals, and they should not be more than .5 volts (?) different, when the car light load is present.

 

Have you checked the 12V battery connections? That could easily cause intermittent problems.

Tom

 

Not wanting to hijack this thread but to check operation of the inverter pump you remove the top off the inverter coolant and then put the car in ready and look for movement in the fluid?

Does the car have to be warm or cold first thing in the morning? Just gonna give mine a check after the odd inverter error codes I go (see other thread).

 

Actually it is not necessary to remove the coolant reservoir cap, to see the turbulence in the fluid.

The inverter coolant pump should be running at all times that the Prius is IG-ON or READY so it doesn't matter whether the powertrain temperature is cold or hot.

 

It isn't only weird that you would describe the battery voltage under load as "somewhere above 10 V" but also tha the original 2006 12 V battery would read 12.5 V on a cold morning.

My '07 battery was at 12.0 before it was replaced and it was never misused, unless of course the car was sitting in the dealer lot before I purchased it.

 

The same (or very similar) thing has happened to me three times now. Here is a quote from my original post. You can search my post to see the entire thread. Car is in the shop as we speak. So far no help.

2006, 2G, 43000K. This has happened twice now. Both times on an extended trip of 3+ hours in hot weather: Cruising along at about 70 MPH, the engine just quits. RED Triangle; check engine light; and vcs light. Turned everything off. Car would not restart right away, but after waiting 15 minutes or so, the car restarts and runs fine. All warning lights off except check engine light.

 

You are wasting time by "exhaustively testing" the 12V battery. Replace it now.

Your car may well have another issue (for example, the inverter may be flaky), but the 12V battery is not very expensive. Instead of spending labor $ to test it, just replace it.

 

12v battery?... if it's original.... probably.. in part

might want to give your ignition coils and spark plugs a check. this sounds like it could be related to those. the trick thing is.. they don't throw their own codes.. it's as if the system doesn't know they are there... till you unplug one.. then it throws a code...