Warning Lights - Troubleshooting before Dealer tomorrow...

2005 Prius with 110,000 miles...

So about two months ago I noticed that my battery was very low when I'd first head out in the morning, and I chalked this up to early am AC drain, but wasn't sure...

Then I noticed the brake pump seemed to be running for a long time after I shut off the car...

Then my wife came home one day after driving in hot weather with the windows down (about 1 mile) and the hybrid battery cooling fan was on (first time we heard this since buying car in 2008).

Then, a few weeks later, several days before I was to drive from Florida to Massachusetts, I noticed that the brake pump would run every 10 seconds or so as I was driving (not in traffic and not using the brake).

I suspected a failing actuator or accumulator pump so I took it to the dealer, and they confirmed this, and, of course, there is no good option at this point, and I chose to have the pump replaced, along with the pads which were at the end of their life, and the drive belt which was original, totaling about $3000.

Now, it is three weeks later and as I was driving today the hybrid system warning indicator popped up in the top left corner of the display screen (looks like a car broken in half), and I have the red triangle, VSC, and other lights on (not brake thankfully).

When this happened, we noticed the voltage readout dropped to no bars (or maybe one bar), and then we ran off the gas motor until it quickly charged up to full green bars (a very rare occurrence).

I checked the 12 volt battery using the on screen diagnostic and that's fine. Reading over 12 volts at first check, and 12 under load, and 14.1 with the car fully on.

I checked the inverter coolant reservoir and the fluid seems to be moving around as I have read it should; that was replaced under recall, so I assume, and hope that's ok.

So, at this point, I suspect the hybrid battery, but I see no loss in performance. I just got 50mpg driving from New York back to Massachusetts last Tuesday and with the warning lights on the MPG readout is still great, 20s going uphill, 99 cruising along, etc..

The dealer that replaced the brake accumulator pump had to remove the hybrid system to get at the brake pump; they actually kept it overnight to re-check the car in the morning to make sure the hybrid system was working ok before giving it back to me, and all indicators were that it was working fine when I left the dealer and drove it over 1000 miles to Massachusetts.

Could this be an early sign of hybrid battery failure? Any other possibilities? Something that wasn't re-installed properly, etc.??

Thanks for any thoughts. I will take to the dealer tomorrow, but I just want to make sure I'm fully informed before I have to start making decisions again on repairs. I don't think I can swallow another $3000 repair for a car this old...

I will report back what dealer says also.

 

Thanks for reply... Nope, warning lights just came on today. I've driven maybe 3 miles back home with warning lights on...

Car was without any lights from the drive from Florida to Massachusetts, then some small trips thereafter... then came on today as I slowed to a stop sign.

I'll double check the vent in the morning, i don't think I have anything in the backseat other than a throw on the seat for the dogs, but that wouldn't cover the vent. Thanks!

 

I didn't understand the removal of the hybrid system, but I guess it was behind there. It was a big job, and an uncommon failure according to the service tech; I think the Toyota warranty booklet specified labor was 6 hours, which is what they agreed to charge me, instead of the 8 hours they initially quoted me. It was a big labor charge on top of the expensive price for the part.

I'll check for dog hair, that's interesting... Little dogs, so not sure how much hair, but anything is possible.

The warning lights came on this morning and I drove to my parents house, as I was almost there... Later in the day, after I let it sit, the display check read 12.1 volts today after the car had been sitting about 7 hours. It then dropped to 11.9 after I pressed start again and it was under load.

I then saw it hit 11.5 as I started the car fully, and then it immediately jumped to 14.1 once I pressed start again and the alternator kicked on.
After driving a couple miles, after that check, back to my house, I checked it again; the 12 volt battery read 12.5 and dropped to 12.1 volts under load (AC on, phone charging off the 12 volt outlet, etc.). I'm thinking the 12 volt battery is still fairly good, even though it might not be like new.

I'm still in Massachusetts. I was in Florida when the brake system started to fail. I got up here to MA at the end of June, got better gas mileage than the last time I made the trip, and then I drove the car to NY to park it for a flight out west. The car sat for about 12 days while I was away on the trip (got back last Tuesday) and it started right up without any issues, so the fact it didn't discharge or act funny after 12 days makes me think it's good, but I'll check it again tomorrow am before I take it to the dealer.

The last time I had the 12 volt battery fail the warning light came on saying the car needed to be in park, or something like that, and I couldn't start the vehicle. It was in March 2010, I was getting 2 or 3 volts on the 12 volt battery, so it was an obvious replacement item.

I didn't get any warning lights that time, the car had been working fine, but the lights had been left on because I started and turned off the car from the passenger side, not knowing that's a no-no in the prius. When I came back to the car, battery was 2 volts and I could jump the car, but the 12 volt battery would not charge anymore.

Maybe I could be looking at a weak 12 volt battery? It has been another 5 years?? But isn't 11.9 - 12.1 under load still good?

 

Thanks for ideas... I thought about a used actuator pump, but was leaving town in a few days and didn't have time for ebay.

The Mini VCI looks interesting, and cheap... I may get one of those. I'm not used to having any issues with this car so I never even thought about preparing for stuff like this, that was one reason I switched from a Saab to a Toyota, so I could stop being an at home mechanic

AM Report:

Didn't see dog hair, but the seat-belt was partially covering the battery vent on passenger side. I probably only drove about 2 miles before the warning lights came on in cool weather (70s), and never heard the battery overheat fan come on, so I don't see that as likely culprit, unless I'm missing something.

I just re-checked the 12 volt battery again. It dropped from 12.5 to 12.1 overnight. Under start up load (with ac fan on) it dropped to 11.5 then rebounded to 11.8. When I turned the headlights on it dropped to 11.0 and rebounded to 11.1. That still seems within spec based on what I've read...maybe a tad low, but only by .2 volts.

Turning the car all the way on made it 14.4 with the alternator running. The warning lights are different today, just a red triangle and check engine symbol, and the "problem", then hybrid car issue icon on the display screen, no more VSC and whatever else was lit up yesterday.

Maybe the 12 volt is a little weaker than new, but I'm not seeing any lights dimming, any issues with running accessories with it in ACC mode, etc., so I think that battery has some life left, even though 5 years old. I don't see the voltage dropping with the accessories on, it remains stable.

I guess I'll go get the codes read...

 

Getting car towed in tomorrow to a dealer about 20 miles away, dealer in town didn't want to see it until Friday.

 

Was just cleaning out car, and ejected a bunch of CDs from radio I have been meaning to swap out and decided to re-check voltage. Car had been on as long as it took to eject CDs. It was at 11.8 on, and 10.7 in ACC mode with lights, fan, and rear defrost on. Perhaps I'm borderline on the 12 volt battery??

 

Gotcha, will do

 

I started up car, took it for a quick drive, and voltages are back over 12 on tests. Would the battery really throw all these codes even if it's showing over 12 volts? the VSC and orange brake warning light are back on now. I am hesitant to unplug the battery if the inverter or something is throwing an intermittent code due to the recent repair... don't want to erase the code, or does it stay stored?

 

no load after a quick drive and an hour's rest is 12.5

 

Found a thread that said if I clear the codes, the tech won't be able to retrieve them. Also found this on voltages, I'm sure you may already be aware of this site, but I'll post for any future readers. My voltage tests yesterday and today have been within spec as normal as described below...

• The transmission should be in Park with the ignition off.
• Engage the parking brake
• Push in the power button. (if not already on)
• Press and hold the "Info" button on the MFD while turning the headlights on and off 4 times.
• Push on Menu in upper right of display screen.
• Push on Display Check
• Push on Vehicle Signal Check
• You will see the 12 volt voltage displayed. In accessory mode the voltage should be 12.6
• With no electrical accessories on including lights the voltage should be fluctuate between 12.6 and 11.9. The lower the voltage, the less of a charge your battery currently has. If the voltage is low do not proceed as the load test might totally discharge your battery. (If you see a voltage around 13.8 you are seeing voltage from the high voltage battery being converted to around 13.8 in an attempt to recharge your battery. This normally does not occur till after you start the engine but might occur earlier if the battery is very drained.)
• You can also test the battery by turning on the headlights, rear window heater and the heater fan. For a new battery the voltage would be around 11.3. If the voltage drops below 10.2 it should definitely be replaced. For voltages in between the lower the voltage, the lower current charge of your battery.
• Push on the brake pedal and push start. You should see Ready in the Speed display. The voltage should now read between 13.8 to 14.2 and higher in winter. This is the charging voltage!

 

Alright, I decided to have AAA flatbed the car to the dealer to have the codes read. That way if it's something the prior dealership did, I'll know what it is, and can move forward to fix it. If they tell me it's the 12 volt battery, I will have wasted money, but not time, and at least I can buy a battery, put it in, and forget about it. If it's worse than that, I'll have to deal with the options... will keep y'all posted. Thanks for your help and ideas and for taking your time to provide guidance. Even if the 12 volt battery is not the issue, I may replace it soon anyway once I see what the big issue is, and how much I need to spend, and where I go with the car in terms of keeping it or upgrading sooner than planned...