Electrical problem

Welcome, Joel. Looks like you're getting your money's worth out of that '05.

By "ignition on" do you mean "ready mode?" Not sure what you mean by "does a reset."

 

Start with the 12V battery. Is it holding a charge? Lots of weird things have been traced to failing 12Vs. Only after the 12V is cleared is it worth looking for other issues.

Gen2 even has a built-in voltmeter: Weird stuff happening? MPGs dropping? Test The Battery | PriusChat

 

Given that you've had it four years, if that's the same 12V battery, it's a likely candidate. As @fuzzy1 said, a low 12V battery makes all kinds of weird stuff happen. There's also the possibility of a loose or corroded ground connection in the battery compartment.

 

I like to check the easy stuff first ....... when I remember to. LOL! I'm not saying the problem necessarily is the easy stuff, but ya never know. Hope you find it soon.

 

i would still test the 12v, it's very suspicious.

 

i wonder if your power switch could be bad? also, check your 12v connections, including neg to ground.

 

This certainly increases suspicions about a loose power or ground connection, as mentioned earlier.

 

How exactly did you "check" them ??

Most likely cause: the battery itself is going bad, including an intermittent internal connection.
Second choice: Even thought the appear clean and tight, one end of one of the main cables is corroded and not making good connection.

The battery voltage needs to be checked WHILE THE FAILURE IS OCCURRING.
Start at the actual battery posts and then go to the connectors and frame ground.

 

Open the hood and put the voltmeter to jump start terminal in the fuse box (other lead to ground). What does the voltage read when problem is present?

Battery ground cable can have bad connection on many different positions including between cable and ring terminal. So check all of them. Also bad connection can be at the positive side including connector between fuse block on battery terminal and car wiring harness.

 

No. All of the connections that I was talking about are near the 12V battery.

Did you check the voltage at the jump start terminal when problem is present? That way we would know for sure that there isn’t any problem at the back.

 

Interesting. My 2011 Prius has 275,000 miles. I have a funky electrical issue as well. Traction control light and exterior brake lights come on during times of heavy road spray. Heavy 'salt' water road spray from winter de-icing. Sometimes the ABS and (!) lights come on with the traction control and exterior brake lights and cruise won't work. But mostly just the traction control and brake lights. Sometimes when this occurs, the auto window would return to the down position when I pressed to the up position. Dealer said no road sensor in the wheel hub code is active. It would all usually go away after a day or so of dry roads. But now traction light and brake lights aren't returning to normal. I think there is a short from salt water intrusion in the front end somewhere. Either that or the car is truly possessed. Other than that the car is still chugging along, truly don't want to throw money at such a high mileage car, but don't want to toss a car and get a new one for an electrical short. Any ideas on tracking that one down?

 

Michael G your in the wrong forum. Post this in the G3 forum this is the G2 forum much older cars advice may not translate.