How to Jump Start a Prius (2016–2022 Gen 4, Including Prime)

Short version: This guide is specifically for the 2016–2022 (Gen 4) Prius, including the Prius Prime — for other years, use our all-generations jump-start guide. A dead Gen 4 Prius is almost always the small 12V battery, which sits under the hood on the driver’s side with a red cover over the positive terminal. Connect red there and black to bare metal, wait about five minutes, then press POWER with your foot on the brake until READY appears.

Your 2016–2022 Prius is dead. The fob won’t unlock the doors, or the dash lights up like a slot machine and the car won’t go into READY. Before you panic about the hybrid battery — don’t. Almost every “dead Prius” we see is the small 12V auxiliary battery, and on the Gen 4 cars it’s the easiest generation yet to jump. Toyota finally moved the battery under the hood, so you no longer have to hunt for a hidden jump terminal like on the 2004–2015 cars.

This guide covers the 2016–2022 Prius liftback and the Prius Prime. If you have an older car, see our guide for jumpstarting a 2004–2015 Prius.

First, make sure it’s the 12V

A Prius has no starter motor. The 12V battery’s only job is to wake up the computers and close the relays that connect the high-voltage hybrid battery. When it’s weak or dead, the whole car acts broken even though nothing expensive is wrong. The pattern we see in the shop every week:

The car won’t detect the key fob — you press the door button and nothing happens.
The dash throws a dozen warning lights at once, sometimes with messages like “Check Hybrid System.” It looks catastrophic; it usually isn’t.
The car won’t enter READY — you press POWER with your foot on the brake and it clicks, flickers, or does nothing.
Everything electrical acts possessed: flickering screens, slow windows, chiming.

A scary hybrid-system message on a car that won’t power up is almost always low 12V voltage confusing the computers — we wrote up why the 12V does this if you want the full story.

Where the 12V battery is on a Gen 4 Prius

On the 2016–2022 Prius and Prius Prime, the 12V battery is under the hood on the driver’s side, tucked back near the base of the windshield next to the fuse box. The positive terminal sits under a red flip-up cover. This is a real change from the 2004–2015 cars, which hid the battery in the right rear of the cargo area and gave you a remote jump point in the fuse box instead. On the Gen 4, you connect right at the battery, like a normal car.

If the battery is completely dead, the fob won’t unlock the doors. Use the metal emergency key hidden inside the fob to unlock the driver’s door, then pull the hood release.

How to jump start it, step by step

Line up your power source. Another car with a 12V battery, or better, a small lithium jump pack. A Prius needs very little current to boot — you’re waking up computers, not cranking an engine — so a compact smart jump box like the NOCO GB40 is plenty, and its reverse-polarity protection is cheap insurance.
Open the hood and find the battery. Driver’s side, back near the windshield. Flip up the red cover on the positive terminal.
Connect the positive (red) clamp to the Prius positive terminal.
Connect the other red clamp to the donor vehicle’s positive terminal (skip this and the next step if you’re using a jump pack).
Connect the black clamp to the donor’s negative terminal.
Connect the last black clamp to bare metal on the Prius — an unpainted bolt or bracket in the engine bay, away from the battery and any moving parts.
Wait about five minutes. If a donor car is providing the jump, start its engine and let it run so the dead battery can absorb some charge. Don’t rush this step.
Foot on the brake, press POWER. Watch for the green READY light on the dash. There’s no engine cranking sound — READY means the car is “running” even in total silence. The gas engine may or may not fire up; either way you’re good.
Disconnect in reverse order: black clamp off the Prius first, then the donor’s black, then the donor’s red, then the red on the Prius. Snap the red terminal cover closed.

The cautions that actually matter

Get the polarity right. Reversed clamps on a hybrid can blow main fuses and damage electronics — repairs that cost far more than a battery. Red to the red-covered positive, black to bare metal. Double-check before anything touches.

Stay away from the hybrid battery. The high-voltage battery under the rear seat has nothing to do with jump starting and nothing under its covers you should ever touch. The 12V system is the only thing that needs help.

Never use your Prius to jump another car. The 12V battery is tiny and the DC/DC converter that supports it isn’t built to dump current into a dead truck. You can damage the converter — a far more expensive repair than a jump box. Your Prius is not a jump pack.

Don’t bother push-starting. A hybrid can’t be bump-started. No 12V power, no READY. Period.

After the jump: the part everyone skips

Find what killed it before you drive off. Check for a glowing dome light, a door or hatch that isn’t fully latched, or a phone charger left plugged in. If a drain caused this and you don’t fix it, you’ll be dead again by morning — we’ve seen cars come back on a tow truck for exactly this.

Let it recharge in READY. A jump only boots the car; it doesn’t refill the battery. Once you’re in READY, the car charges its own 12V from the hybrid battery — and sitting parked in READY charges it just as well as driving. Give it 30 to 60 minutes with the climate control, lights, and stereo off. Powered off, it charges not at all, so don’t shut it down two minutes after the jump.

Then get the battery tested. A 12V that died once without an obvious cause is usually a battery on its way out — they last roughly 4–6 years, and short trips and long sits age them faster, because the battery only charges while the car is in READY. The Gen 4 takes a normal-size battery (LN1 / H4 / group 140R); we install quality AGM replacements and test the charging system while we’re at it.

When to call a shop

Jump it yourself with confidence — that part doesn’t need us. Call a shop when the battery dies again within days with no light left on, when the car still won’t enter READY with a known-good 12V connected, or when warning lights stay on after voltage is restored. Those point to a parasitic drain, a charging problem, or an actual hybrid-system fault, and that’s diagnostic work.

Frequently asked questions

Can you jump start a Prius from another car?

Yes. Any car with a working 12V battery — or a portable jump pack — can jump a Prius, because it’s the small 12V auxiliary battery that needs the boost, not the high-voltage hybrid battery. Just connect carefully and in the right order; hybrid electronics do not forgive reversed clamps.

Where is the 12V battery in a 2017 Prius?

Under the hood on the driver’s side, near the base of the windshield next to the fuse box, with a red cover over the positive terminal. That’s true for all 2016–2022 Prius models, including the Prius Prime. On 2004–2015 models it’s in the right rear of the cargo area instead.

Can a Prius jump start another car?

No — don’t do it. The Prius 12V battery and DC/DC converter aren’t designed to supply the heavy current a conventional starter motor pulls, and you can damage the converter trying. Keep a jump box in the trunk instead.

How long should a Prius run after a jump start?

Leave it in READY for 30 to 60 minutes — parked is fine, since the car charges its 12V battery whether it’s moving or not. If the battery was completely flat, give it a few hours or put it on a proper charger, and have it tested.

12V battery testing and replacement in Portland

Atomic Auto has specialized in hybrids in Portland for over two decades, and dead 12V batteries are the single most common “my Prius died” call we get. If your battery needed a jump and you’re not sure why — or you’d rather replace it before it strands you — we test the battery and charging system and install quality AGM replacements. Contact us to schedule an appointment.