How to Get a Prius into Diagnostic Mode

hello and welcome! you're better off checking it under the hood with a digital volt meter.

 

If you look on youtube I saw a how to vidio on there to get to diagnostic mode.

 

If you are talking about maintenance mode where engine keeps running, then the instructions are same for both the generations. if you are talking about diagnostic mode on GPS models then instructions maybe different, i remember getting into it once about couple of years ago but dont remember how, i found instructions here on these forums.

 

For 2010 models

You must have NAV since you need an MFD.
1) Apply parking brake
2) Press Power Button twice, foot not on brake pedal. You are now in accessory mode.
3)Hold down Info button on right side of MFD. and at the same time turn Headlights on and off 4 times.
4) A menu will appear on MFD.
5) Select Fault diagnosis to see battery voltage.

 

for 2012 models with MFD
from another thread i copied
"On my 2012 Prius II I was able to access a diagnostic screen in ACC mode by turning the headlightson/off 4 times while depressing the "car" button next to mfd screen. A couple of screens down from the main screen brings up a "signals" screen (similar to that on my 2007 prius), which shows the 12V battery voltage. Doing this while holding down the "settings" button brings up a different diagnostic screen which I didn't explore."

 

Tried your instructions on my 2012 Prius v five today. Noticed I didn't need to depress parking brake. Just hit power button twice, then hold down info button, then headlight switch on and off 3 times and a screen came up with 3 choices. I picked the middle one (system check I think ), then click on vehicle signal. That showed me the voltage of my 12 volt battery. It read 11.9 volts. I killed
the battery over the weekend and charged it up yesterday and drove back and forth to work with NP today. First time I killed this battery in 5 years. May have to replace before winter. Looking at the yellow top optima on sale at Pepboys.

 

^ Yeah, if you're just talking about the 12 volt: do yourself a favour and get a multimeter. It'll pay for itself just checking all the AA batteries you're not sure of, lol.

Or get more serious, look into Solar BA5.

 

My battery is in the very back of the car buried under all kinds of stuff and is a "pita" to get to.

 

As @bisco said, you can connect at the under-hood jumpstart point. For that matter, I can't see the hatch area battery access being that tough, if it's similar to 3rd Gen Prius, you lift off the hatch floor, then the underfloor tray.

 

I have the back loaded with dog cages for transporting my dogs . I have heard of the jump start point up front but don't know where it is. Can you also charge your battery from the front? Thx for your replies.

 

yes, it's in the fuse box. instructions are in the o/m.

 

Use one of these in the 12v outlet...

 

^ Unfortunately the 12 volt outlets only have power when the car is on (or in accessory mode?). Either way, the readings would be skewed I think, by peripheral loads.

You can get decent multimeters for $40~50, cheap for under $20. Connect at the jump point, car off, is easy.

The Solar BA5 gives more comprehensive assesment, not just voltage, but must be connected directly to the posts. It's around $70?

 

Thx Bisco. Found it and tested with my Fluke meter. Battery read 12.3 volts at that point with everything off in the car. Went inside and brought up the diagnostic screen and it showed 11.9 volts inside and 11.9 volts outside. Didn't think turning on just acc. would knock it down 0.4 volts. Now I know. Also, I can now check the voltage from inside the car in less than 30 sec. without a volt meter. To me it looks like I still have a good battery.

 

keep an eye on it, it is getting close to the edge. as voltage drops below 12 with a load, the computers can start doing funny things.

 

Just for grins, when some of you have time, could you go into your diagnostic menu and see what your 12 V battery is reading. Thanks, Ben.

 

click the report button, and ask for it to be deleted. in the meantime, edit your post, removing all the words and type 'duplicate'.

 

Thx Bisco