Computer powers up but won't start - main display and radio go dark

Initial thought is the 12V battery, even when jumped from another car, isn't providing enough voltage to start the car. When trying to start, the power needed to close contractors in the main HV battery draws down the 12V until it's two low for the screen.

 

You say the car sat idle for several months. The traction battery that starts the engine has run down and can’t produce enough voltage to crank the engine. The 12v hookup will still light up the display. You’re gonna have to get the big battery recharged, if it isn’t completely dead after sitting so long. You may be SOL.

 

Likely this.

BUT the 12 V system needs a thorough test BEFORE delving into the hybrid battery.

IF.....the onboard 12 V battery has a shorted cell or two, it can drag down the
jumped battery too. And might result in SMOKE if left connected too long.

 

Perhaps. Disconnect the old 12v and jump directly into the battery connections. If car gets “Ready,” then you have your culprit.

 

Also, of course, if you do manage to get the car "Ready," and if all systems are functioning properly, the traction battery will be charging as long as the ICE is running. (One way to keep the ICE constantly running is to activate the MAX a/c button.) And you do need to check out that 12v battery, as previously noted.

 

Looks like the HV battery is charged.

 

Seems rather late to bring this up, but have you done diagnostics, I.e., pulled any trouble codes, and if so, what are they? Or have I missed something?

 

That's no good at all. Not all the features of the Dr Prius app work on Gen1's, but it's still able to read the pack and blade voltage. Blade nominal voltage is around 7.2V, so the pack should be around 274V, not in the single digits. Not sure why the SOC still looks good.

This is how it looks on my '01 with the ignition on before starting the car. Note, the app does not read the 12V battery voltage.

 

Build yourself a “grid charger” - it’s cheap and easy - and charge the traction bat.

 

Looks like I nailed it on my first post in this thread. So if this were my car, I'd look into replacing the traction battery from one of the outfits that will install it in your driveway. Do an internet search.

 

Yeah I’ve done it. Basically a Meanwell LED power supply which provides 275v at very low amps. You should be able to find good instructions on Prius Chat with a little searching. I didn’t even use a diode, just an old electric light house switch. Total cost around $65

 

Grid chargers can be used to recondition good working batteries, but will not recover a dead pack. If the Dr. Prius app is accurate, your pack is way below the threshold where irreversible cell reversal can occur. It still has a $1300 value as a core when purchasing a new pack from Toyota.

 

A grid charger can be used to charge an HV bat which is below the level at which an engine start can be accomplished. It’s a cheap alternative to going to Toyota to get a charge.

 

Here are some sources for the HV battery. I have a Dorman installed in my '02, and so far, so good, although the first one installed was defective and replaced under warranty (not the install labor, though; had to pay for that). When I did the math, I figured $2-$2.5K was much cheaper than either a new or used car, and I got to keep the car I really like a lot. But, you pays your money and you takes your choice. Good luck with your decision, and let us know how it turns out!

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