Maintenance Mode and Battery Voltage

About half way down the web page you'll find an alternative method, which works on my Prius.

12 Volt (12v) Toyota Prius Auxilary Battery for 2004, 2005, 2006, 2007, 2008 and 2009 with free shipping

 

Erm, Sorry I meant click on the link that I provided, hopefully you web browser displays the link in my message as underlined or different colour (the text begins with "12 Volt (12v) Toyota Prius Auxilary Battery for...").

(BTW I've got a nasty dose of flu at the moment so don't expect me to make too much sense - hehe at least I've got an excuse this time!).

 

In mine the smart key has stopped working reliably now that the unloaded battery voltage (measured with a voltmeter at the charge point under the hood and the car OFF) has dropped to 12.1. I've ordered the Optima and kit from Elearnaid.

 

after consistently experiencing weak/limited start-up power from my auxiliary battery, i performed the "battery test" listed on Elearnaid. it showed 10-11 volts after 30 minutes of driving on three different tests.

so, i too, ordered the Optima and kit. should arrive tomorrow.

will let you know results.

 

Whoa! Yeah, at 10V a lead-acid battery is at death's door. Have you noticed any odd behavior?

 

what i noticed was that after being parked for 2-3 days, the interior lites were dim, but it would start. any longer that that, and i needed a jump.

anyway, that's all in the past now. did the Optima upgrade yesterday and am not looking back!

 

I've owned my 2004 prius for over 2 years and it's been great and mostly problem-free. Yesterday though, while driving on the 405, doing about 65, my cruise control suddenly cut off, and I got the dreaded "triangle of death" and the "turtle" on my MFD.

I continued driving and didn't notice anything unusual with the handling or performance of the car, and went about my day as usual, hoping I would not get stranded somewhere. I also drove many miles today and at one point, the warning lights disappeared, and I thought I was in the clear.

They soon returned, and so when I got home I started checking the internet for clues. I then starting thinking that the problem could be linked to my 12 volt battery; it came with the car when I bought it, and I don't know if the last owners ever changed it, or if they did, when that was.

So, I just tested the 12 volt battery using the maintenance mode check as outlined here, it was barely registering 12v while UNloaded, and then when loaded it dropped to 11.8. Then the final "charging" mode test was normal at 14.v.

So, would 11.8 under load be considered bad, and time to replace, and more importantly, could this be the reason for the triangle and turtle waring lights?

If so, and I go ahead and replace the 12v battery, will those warning lights automatically go off, or do they need to be reset, like when you do an oil change? Thanks in advance for any help.

 

That's means it's a weak battery and you probably should change it fairly soon, but I don't think it's bad enough to cause the problems you mention. Since it's about time to change it anyway then you may as well do it and see if it helps.

 

Thanks for the reply. I should mention that when I did the 12v test. my prius was fairly cold and hadn't been driven for a few hours...does that matter? Should the test be done when the car is at normal operating temps, or just warm?

Anyway, I just did the test again after driving a couple of miles. This time the voltage was 12.4-12.5 unloaded, and still about 12.1 when loaded, but when I turned the headlights on (car was not started) it dropped to about 11.8. Is this a more accurate reading?

So if it turns out that the warning lights still stay on after replacing the 12v, could the problem be in the main battery pack? It is also just about at 100k miles.

 

The various threads prompted me to do the voltage check as well on my 2007 Prius that's been in service since late 2006 (though low mileage...only 21K!).

Unloaded: 12.2 volts
Loaded (headlights, rear defrost): 11.9
engine on, charging, 14.3

I do only light driving; my "commute" is 3 miles (10 minutes), so the car hardly has a chance to charge the battery.

I know these voltages aren't dangerously low, though one thread suggested that the unloaded/loaded figures should be >12.4/>12, which mine aren't.

Under the circumstances, worth changing the 12v battery "prophylactically"? Or just let it go for awhile?

 

1. I would replace the 12V battery at this time. The correct time to check battery voltage is after the car has been sitting overnight, or at least after a few hours have passed after the car was last driven. You will not have useful results if you check battery voltage immediately after the car has run.

2. However, I don't think that the 12V battery is the cause of your problem. My guess is that your inverter coolant pump has failed. Check the inverter coolant reservoir when the car is IG-ON (the mode where all instrument panel warning lights are on, not READY) to see whether you can see turbulence, and listen for the sound of the pump which is located immediately behind the driver's headlamp assembly.

3. I don't know what an MFD turtle warning icon is, on a 2G. Perhaps you are referring to the warning icon which is the outline of a car with an ! superimposed on it? That is the hybrid system warning icon. (Classic did have a turtle warning light whose purpose was to show that the traction battery temp was excessively high and that limited power was available.)

4. When you disconnect the 12V battery cables, that will clear whatever DTC had been logged by the engine, hybrid vehicle, and traction battery ECUs.

If you have a decent digital multimeter available to you, I would suggest measuring the battery voltage with that instrument. There's some inaccuracy with the MFD display. The fact that you measured 14.3V when the car is READY leads me to think that perhaps the MFD display is reading high by as much as 0.5V since I expect the measurement to be ~13.8V.

I would recommend replacing the 12V battery as a preventive move if you would be unduly inconvenienced with a battery failure.

 

Can I continue driving with a bad inverter coolant pump?
And yes, one of the warning lights (icon) I'm getting is the outline of a car with an ! in the middle of it. You say it's the hybrid system warning icon. What does that mean exactly? Is my hybrid main battery system failing? Is this something major? Again, my car is driving fine as usual, with no apparent malfunctions, other than those warning lights.

 

Very short trips in cold weather may be OK, but why risk the inverter (many $K)?

 

What does the coolant inverter do, and what is the approx. cost for parts & labor?

 

When the hybrid system warning icon appears, that tells you that something is wrong with the hybrid system, and this warning should not be ignored unless you don't mind having your car stuck on the side of the road.

The inverter coolant pump circulates coolant through the inverter and the transaxle. You'll probably pay ~$400 at the dealer to have it replaced.

 

Yep, just got the call and they said I needed a new inverter coolant pump, and also a coolant flow control valve. What was surprising is that they also tested my 12v battery and said it passed with flying colors! Go figure. They told me after replacement of these two parts, the warning indicators will go away; triangle, check engine light, and hybrid system icon on mfd. 1 year warranty on parts and labor.

 

I was given the labor charge for the work to be done, and was told that I would have my car back by 3pm today, and that they would be starting work on my car about 11:45am, so roughly three hours of labor. I asked for a cost break down and the total labor charge was about $715 (!!!)

I thought to myself wow, that would translate to almost $283 per hour for labor alone! So I called back and asked the service person how this could be, and she told me that it depends alot on the actual job, how many people are working in it and even if they finish the job early, they still get paid for the labor based on the job.

Does this sound right, or more like I'm getting scammed and ripped off? She confirmed with me that I would have my car in 3 hours, so I asked her how they could justify more than $280 per hour labor? I called my local independent guy and based on the exact same job, he told me he would charge me $200 labor, PLUS include the 2 gals of coolant that the dealer also wants to charge me an additional $50 for!!!

So I again called the dealer back and told them what my indy guy quoted, and that I would take it there unless they gave me a lower price. She went to talk with her supervisor on my request, came back on the line to say that they would take 25% off the total bill, and of course not charge me the $95 diagnostic fee since the work would be done. Still seems shady to me, but I agreed to the discount.