Voltage Reading from Fuse Box +12V Cleat to Ground When 'Running'

My Scangauge II shows 14.4 v but I do not have a multimeter.

 

i'll check mine. the cold reading yesterday morning was 12.87

 

mine reads 14.57 at the fuse box, car in 'ready', that is, foot on brake, press power button once.

 

It is a data value on the OBDII bus perhaps in the inverter. The cleat in the front fusebox is attached to the battery by a long, large cable

 

huh, i wonder if pip is different.

what does it read with the car off?

 

interesting. hopefully, someone with a v and multi meter will check.

 

Voltages on my 2012 v, I get 12.7 vdc when system is off as measured at the fuse box takeoff, 11.7 when ON and AC/Lights on but not in ready, and 14.27 vdc when in Ready Mode with AC and lights on.

The car had just been run about 50 miles 15 minutes before my measurements, so the12v battery probably did not need much charge. I would consider an inverter problem with no real change from off to Ready. Is it actually coming on and saying Ready?

 

ya, that kine of stuff in a prius is tricky.

 

14.4v at fuse box in Ready Mode on our hatchback.

I've used a delay timer relay in the past to spare my relays the voltage spikes during startup. This one has variable setting:

DRL Timer Switch 12A 12V Time Relay 3 110 Sec Delay on Running Car Daylights | eBay

 

You could just tap into the fuel injectors or ignition coil circuit. Those are only energized when ig2 is energized. Is IG2 normally open or normally closed? You know what I mean.

Apparently you can also tap off the washer fluid pump or inverter.
Highbeam 50% DRL mod, completed | Page 3 | PriusChat

 

A safer but not as satisfying solution would be to tie into glove box light circuit which is always and only on when headlights are on.

If you had a 2014 then I would have also said the DRL circuit but I think your 2012 doesn't have DRL.

 

Those gadgets (like the InPower VCM-06) typically work great in a Prius.

Something very peculiar seems to be going on with your particular Prius. You can see that the others responding to your question are doing the same measurement and getting the expected value (high 13s to mid 14s when the car is READY ON).

Before diving too deep into possible explanations why your Prius is different ... are you sure it is READY ON when you make this measurement?

-Chap

 

When a ScanGauge shows 12 V bus voltage, it may be measuring directly. One of the standard OBD-II connector pins is specified to be an unswitched 12 V supply. (This is why caution is recommended when probing pins in that connector, even if the car is off.)

-Chap