"Hybrid System Warning" light

Which light are we talking about: is this the red ! superimposed upon the outline of a car, appearing in the MFD? Are any other warning lights on?

It's not safe for your wife to plan to drive 30 miles without knowing the root cause of the problem.

The generic OBD-II code reader available at the auto parts store cannot be relied upon to retrieve DTC associated with the hybrid vehicle ECU or traction battery ECU.

 

Well, if the inverter coolant pump was the root cause, then as the inverter overheats, the DC/DC converter would allow the 12V bus voltage to sag. That would result in the brake, ABS, and VSC warning lights to come on.

Since your wife did not report this, I do not think that is the problem.

If the throttle plate was the problem, then I would expect the check engine light to come on, not the car with !. The latter warning is telling you something is wrong with the hybrid vehicle system.

I recommend that you have your wife immediately drive to the nearest Toyota dealer so that the DTC can be read and she can rent a car to carry out her daily agenda. Good luck.

 

The Toyota dealer is likely to be the only place that can reliably read the diagnostic trouble codes as well as the info subcodes that provide additional information about the problem. This is because a special diagnostic laptop is required to retrieve this information. Also, you'll want to know what the tech's diagnosis and estimated repair price is.

An independent shop that specializes in Toyota may also have this test equipment available. It is unlikely that an independent which is a generalist will have this.

If the Autozone staffer had cleared the DTC, then there's no point in taking the car to the Toyota dealer now. You'll have to wait until the warning lights reappear.

When that happens, immediately take the car to the dealer without delay and ask the service writer to have a tech come out to retrieve the DTC before the car is turned off. Good luck.

 

If the master warning triangle and the hybrid vehicle warning icon are the only items that appear, then really, any number of hybrid system issues might be causing the problem, including:

1) transaxle failure
2) inverter failure
3) traction battery failure
4) hybrid vehicle ECU failure

It appears that the problem is intermittent at least for now. Does your wife notice any driveability issues or unusual noises? Has the car's mpg declined?

 

Hi Patrick Wong, some of your above questions are totally on point for my situation, so I am hoping that you can advise on what you were thinking in asking them. Recently, my 2005 Prius has been more sluggish and slower in accelerating. The car's mpg has declined from 40+ to 33ish. Today, I started my car to go to lunch and these warning lights came on:

1) Red ! triangle (I think called Master Warning light) with the red ! superimposed upon the outline of a car, appearing in the MFD (I think called Hybrid System Warning Light) and the MFD says "Problem"
2) Yellow ! indicator (I think called Brake System Warning Light)
3) Check engine light

A friend checked my 12 volt battery and it is fine. We noticed that the inverter coolant was low. Engine oil was a little overfilled (I won't be taking my car to the same oil change place again). I haven't driven the car since the lights came on because I was too worried to drive it and I am thinking of having it towed to a dealer. In your above post, you specifically mentioned a decline in mpg, so I was wondering where you were going with that? Would appreciate your thoughts! Thank you!

 

I'm not Patrick but the next course of action is simple. You have trouble codes posted (the warning lights) so get them read. An auto parts can read some (but not necessarily all) of them for free while a Toyota dealer can read them all of course but usually for a diagnostic fee.

If your 2005 is still on the original HV battery, it's most likely dying but the codes will tell us for sure.

 

Odometer reading?

A mpg decline is indicative that the powertrain efficiency has been reduced. This typically results from an engine problem or a traction battery problem.

As previously suggested, the diagnostic trouble codes (DTC) need to be retrieved. It appears that your car has at least one serious issue since the ! superimposed on a car outline warning icon has appeared in the upper left corner of the MFD. That points to a hybrid drivetrain problem.

 

Thanks Fotomoto and Patrick Wong. I've attached the Vehicle Diagnostic Report from the dealer because I am not positive I am reading it correctly...Looks like several codes were pulled: P3000, P0A80, P3013, C1259, C1310, and B1421. Odometer reading is 145,000 miles. The dealer says that I do indeed need a new hybrid battery - says that block 3b is failing.

Before taking my Prius into the dealer today, I checked the inverter coolant for waves and ruled out the inverter coolant pump as a possible suspect (there were waves in the coolant). I am still concerned about the low coolant level, but the dealer didn't seem concerned. The low level is about an inch below the low line. I'm planning to have an inverter coolant change done, but I read somewhere that the coolant should never be low unless there is a leak, so I'm concerned. Should I be concerned about the low level? I bought the car with 100,000 miles on it and so I doubt an inverter coolant change has ever been done. :-/

 

I wouldn't worry about anything other than the battery. I would recommend you asking Toyota corporate for a goodwill warranty for the battery replacement. The service dept can do this for you

 

I agree that the traction battery needs to be replaced. It would not hurt for you to see whether Toyota might offer you financial help with the repair cost.

Yes, the inverter coolant change should be done and the mechanic should look out for a leak in that system.

I prefer Tustin Toyota (vs. Irvine Toyota) and also received excellent service from Rancho Santa Margarita Toyota when living in south OC.

 

The refurbished battery comes with a 3 year/unlimited mileage warranty. I'm going to make sure to get that in writing!

 

Toyota is chipping in a decent junk toward the repair cost, so I'm thankful for that. I'm proceeding with the inverter coolant change and praying that they don't find a leak. I'll keep Tustin Toyota and RSM Toyota in mind for the future. Thanks so much!