Can the inverter draw current from the 12v system?

Let's see if I have this straight:
If your foot is NOT on the brake and you push the ON button, it doesn't go all the way to the READY mode and essentially is just in ACC mode.......where it will draw from the 12 V battery and that is normal. The inverter is not active.

If you do go to READY, which most people probably think of as "ON", then the 12 V battery should NOT be showing a net discharge.

 

No, the inverter won't draw current from the 12V in ON (as opposed to READY). But a lot of other stuff will drain the 12V and since the car isn't in READY, the inverter & traction battery will not maintain the 12V charge. There are dire warnings in the owner's manual about this practice.

 

Answer is the same. If it's not in READY, it will drain the 12V. It's not the inverter draining it; it's all the computers and other stuff on the 12V bus.

 

It's not a matter so much of "firing up," I think. It just doesn't have any input power from the traction battery or the MGs. You may have an issue with the inverter pump, though. I don't have experience with Gen 1, but the pump on later models does run in either ON, ACC or both. Not sure which. If you're hearing a hum from that area and it's draining the 12V fast, it's a good place to look.

Maybe we can flag @Elektroingenieur to see if he knows. And he probably does know.

 

Turning the key to 'start' on a Gen 1 is like pressing the button with your foot on the brake in a Gen 2. It is a signal to the HV ECU that you would like starting to happen.

The HV ECU then looks around to make sure things are sane, and if they are, signals the system main relays in the traction battery to close, signals the inverter to, um, invert, drives the output transistors to send juice to MG1, suggests to the engine ECU that a nice 1000-or-so rpm idle would be welcomed, and poof!, you're in business.

The Gen 1 inverter cooling pump does run whenever the key is ON.

 

I wonder whether your inverter coolant pump isn't seized up (or close to it). Those are a common failure item, and if seized up somehow would ramp up current draw. I don't know the technicals in the AM2 fuse, but your observations would fit with that.

 

I would wonder about the pump making an audible buzz/hum if seized up though. But it should be easy enough to check, nothing more than the old look-for-reservoir-turbulence trick.

 

Yeah. I was thinking more about it and seized made less sense than something like on its way to seized - spinning but jammed up somehow. Or even a system blockage. Anything that would put excessive load on the pump. Fortunately I haven't had to mess with my pump. But unfortunately it means I don't know how they're constructed so can't speculate on pump near-failure modes if there are any.

 

EXACTLY what leads you to believe that ?
The normal load coupled with a weak battery or a bad connection can make it LOOK like too much current is being drawn when it really is not.

Further "discussion" of your situation without you checking the battery and it's main connections first is just a waste of everybody's time.

 

I've read 3 threads concerning issue, Here in the Newbie section and the techstream thread.
Both here and the newbie section threads have a bunch of posts all trying to be helpful.
I've been looking around to get more info on the gen1 and I started by searching for the location of the 12v - probably under the hood, but it would take me forever to dig up my gen1 pics to confirm.

I'm not a pro either, and electical for me has been one of the three most difficult aspects to grapple with on cars, not to mention utiltiy supply.
I've done some beginner diagrams and troubleshooting and it's a steep learning curve for me too.

Searching gen1 ain't easy either.

found these wiring diagrams - classic prius 2001 electrical diagrams at DuckDuckGo

or search classic prius 2001 - thanks john1701

between techstream, search terms and diagrams you'll find the reason.

 

It's in the trunk, on the left side. Prius aux batteries didn't move under the hood until Gen 4.