How to Jump-Start a Car, Step by Step

Connect red to the dead battery’s positive (+) post, red to the donor’s positive (+), black to the donor’s negative (−), and black to an unpainted metal ground on the dead car; start the donor, wait a few minutes, start the dead car, then remove the cables in reverse order. Alternatively, use a portable jump pack following the same red–positive/black–ground sequence. This guide explains the safest, most up-to-date procedures, key exceptions for modern vehicles, and what to do if the car still won’t start.

Safety First: When Not to Jump-Start

Before you connect anything, confirm it’s safe to proceed. The situations below can make jump-starting dangerous or ineffective and call for a tow or professional help instead.

• Battery is cracked, bloated, leaking, or smells strongly of rotten eggs (sulfur) — risk of explosion or acid burn.
• Battery is frozen (often below −10°C/14°F); thaw indoors before attempting any charge.
• Unknown or mismatched system voltage (most passenger cars use 12V; do not mix with 24V or 6V systems).
• Electric vehicles (EVs) should not be used as donor vehicles; consult the manual for EV-specific 12V jump-start points if the EV itself needs a jump.
• Modern hybrids and 48V mild hybrids: only use the designated 12V service posts; never touch the high-voltage system.
• Severe cable corrosion, frayed jumper cables, or incorrect polarity markings you can’t verify.
• Fuel leaks, exposed wiring, or any sign of electrical short; keep sparks away.
• On busy roads without safe space or visibility; call roadside assistance instead.

If any of these apply, do not proceed. The safest option is to consult the owner’s manual or contact roadside assistance to avoid injury or damage.

What You’ll Need

Having the right tools makes the job faster, safer, and more reliable. Gather these items before you begin.

• Jumper cables, preferably 4-gauge or thicker (2-gauge for trucks/large engines), with good spring clamps and intact insulation.
• A donor vehicle with a healthy 12V system and similar engine size, or a quality lithium jump pack rated for your engine displacement.
• Owner’s manual(s) to locate approved jump points and any vehicle-specific instructions.
• Safety glasses and gloves to protect against sparks and acid.
• Wire brush or terminal cleaner to remove light corrosion on posts/clamps.
• Flashlight if working in low light.

These basics cover most situations, but always defer to the vehicle’s manual for exact jump-start locations and cautions, especially on newer models with battery management systems.

Jump-Starting with Another Vehicle

Position and Prep

Set up the vehicles and batteries so you can connect safely without strain on the cables or risk of contact with moving parts.

1. Park the donor car close enough for cables to reach, but ensure vehicles do not touch. Set both in Park (automatic) or Neutral (manual) and engage parking brakes.
2. Turn off ignition, lights, HVAC, and accessories in both cars. Remove keys on key-start vehicles.
3. Open hoods and identify battery posts or designated jump points. Positive is marked “+” or red; negative is “−” or black. Flip up any protective caps.
4. Brush off light corrosion from terminals. Do not attempt if posts are severely damaged or loose.

Confirm polarity twice before you attach anything. A single reversed connection can blow fuses, damage ECUs, or trigger safety pyrofuses.

Cable Connections (In This Order)

This connection sequence minimizes the chance of sparks near the dead battery, where hydrogen gas may be present.

1. Attach one red clamp to the dead vehicle’s positive (+) terminal.
2. Attach the other red clamp to the donor vehicle’s positive (+) terminal.
3. Attach one black clamp to the donor vehicle’s negative (−) terminal.
4. Attach the remaining black clamp to an unpainted, solid metal ground on the dead vehicle (engine block or chassis), away from the battery.

Ensure clamps are secure and not touching fans, belts, or each other. If you see heavy sparking, stop and recheck connections and polarity.

Start and Charge

Bring the dead battery up just enough to crank the engine without overstressing components.

1. Start the donor vehicle and let it idle 2–5 minutes; gently hold 1,200–1,500 rpm to boost alternator output if safe.
2. Attempt to start the dead vehicle. If it doesn’t start, wait another 3–5 minutes and try again. Limit cranking to 5–10 seconds per attempt with a 30–60 second rest.
3. If the engine starts, let both vehicles run connected for a couple of minutes to stabilize voltage.

If the dead vehicle still won’t crank after three attempts, suspect poor connections, a failed battery, bad starter, or charging/immobilizer issues. Don’t keep cranking; you can overheat the starter.

Disconnect in Reverse Order

Removing the cables in reverse reduces spark risk and keeps the system stable as you separate the cars.

1. Remove the black clamp from the revived vehicle’s ground point.
2. Remove the black clamp from the donor vehicle’s negative (−) terminal.
3. Remove the red clamp from the donor vehicle’s positive (+) terminal.
4. Remove the red clamp from the revived vehicle’s positive (+) terminal.

Keep the clamps from touching and stow the cables. Replace any protective terminal caps and ensure no tools are left in the engine bay.

After It Starts

Once running, help the battery recover and check for underlying problems that caused the discharge.

• Drive 20–30 minutes at road speeds to recharge; avoid shutting off immediately. Idling alone charges slowly.
• If the car dies again soon, the alternator, belt, or battery may be failing; test system voltage (typically 13.8–14.7V while running).
• If your car has stop-start or an AGM/EFB battery, ensure it’s charged correctly; frequent deep discharges shorten its life.
• Reset clocks, radio presets, and window or sunroof auto-up if needed; consult the manual for reinitialization procedures.
• If the battery is over 3–5 years old or repeatedly discharging, consider replacement and a parasitic draw test.

Treat a jump-start as a symptom check: if problems persist, schedule a battery and charging system test.

Jump-Starting with a Portable Booster Pack

Jump packs can be safer and faster than using another vehicle, especially in tight spaces or when no donor car is available.

1. Verify the pack is charged and rated for your engine. Power it off before connecting unless the manufacturer specifies otherwise.
2. Connect the red clamp to the battery’s positive (+) post or the vehicle’s designated positive jump terminal.
3. Connect the black clamp to a solid, unpainted metal ground on the vehicle (not the battery’s negative post unless the manual instructs).
4. Turn on the jump pack. Some smart packs require a confirm/override if the battery is extremely low.
5. Start the vehicle. If it doesn’t start within 5–10 seconds, wait 30–60 seconds and try once or twice more.
6. Turn off the pack, then remove clamps in reverse order: black (ground) first, then red (positive).
7. Recharge the jump pack after use so it’s ready next time; lithium packs lose charge over months and in cold weather.

Follow the pack’s manual closely. Smart clamps can detect reverse polarity and short circuits, but you should still double-check connections before powering on.

Troubleshooting: If It Still Won’t Start

Persistent no-start after a correct jump often points beyond a flat battery. Use these clues to narrow it down before calling for service.

• Single click or rapid clicking: weak battery, poor clamp contact, or bad starter relay/solenoid.
• No dash lights/power: blown main fuse, bad battery terminal connection, or completely dead battery.
• Cranks slowly and cables get hot: cables too thin/long, corroded, or internal battery failure.
• Cranks normally but won’t fire: fuel delivery, ignition, crank/cam sensor, or immobilizer/anti-theft issue (look for a flashing security light).
• Starts then stalls immediately: alternator not charging, broken/loose serpentine belt, or severe voltage drop under load.
• Automatic won’t crank in Park: try Neutral; could be a faulty range (neutral safety) switch.
• Diesel engines: allow glow plugs to cycle; weak glow plugs or low-temperature fuel gelling can prevent start.

If basic checks don’t resolve it, arrange professional diagnostics. Repeated jump attempts can damage the starter and wiring.

Special Cases and Modern Systems

Today’s vehicles may include features that change how and where you connect. Be mindful of the specifics below.

• Stop-start systems and AGM/EFB batteries: use the marked jump posts; don’t connect directly to a battery buried under seats or in the trunk unless instructed.
• 48V mild hybrids: never touch the 48V battery; jump only via the 12V service terminals noted in the manual.
• Hybrids (e.g., Prius): you can usually jump the 12V system at the engine bay post; do not attempt to jump the high-voltage pack.
• EVs: do not use an EV as a donor unless the manufacturer explicitly allows it; follow manual procedures to energize the EV’s 12V system.
• Memory savers: helpful during battery swaps, but avoid using them while jump-starting.
• Dual-battery trucks or diesels: follow the manufacturer’s sequence; some require specific grounding points.
• Reverse polarity risks: many late-model cars have pyrofuses or smart battery sensors; a wrong connection can trigger costly damage instantly.

When in doubt, follow the exact steps in your owner’s manual for jump points and sequences; manufacturers can vary in their prescribed procedure.

Environmental and Legal Considerations

A few practical and regulatory reminders can keep you safe and compliant while dealing with a dead battery.

• Avoid idling for extended periods where prohibited; local anti-idling laws may apply.
• Use hazard lights and triangles if stopped roadside; prioritize visibility and safety.
• Never smoke near batteries; wear eye protection and wash skin that contacts battery acid.
• Recycle old or failed batteries at auto parts stores or recycling centers; improper disposal is illegal in many regions.
• Roadside assistance (e.g., AAA, manufacturer programs, insurance add-ons) can test and replace a battery on-site in many areas.

These steps protect you, other road users, and the environment, and can save time if a replacement is ultimately needed.

Summary

To jump-start safely, connect red to positive on the dead battery, red to positive on the donor, black to negative on the donor, and black to a solid ground on the dead vehicle; start the donor, wait a few minutes, start the dead car, then disconnect in reverse. A jump pack follows the same clamp order. Avoid jump-starting damaged, frozen, or high-voltage systems, and use designated service posts on modern vehicles. If the engine still won’t start after proper procedure, pursue diagnostics for the battery, alternator, starter, or immobilizer.

What are the steps for jump start?

To properly jump-start a car, park a working vehicle close to the dead one without touching, then turn both cars off. Connect the red (positive) clamp to the dead battery’s positive terminal and the other red clamp to the good battery’s positive terminal. Connect the black (negative) clamp to the good battery’s negative terminal and the other black clamp to an unpainted metal ground on the dead car’s frame. Start the working car, then the dead car. Disconnect the cables in the reverse order. 
Before You Start

1. Position the cars so the jumper cables can reach both vehicles, but ensure the cars do not touch. 
2. Turn off both cars, engage the parking brakes, and ensure both vehicles are in park or neutral. 
3. Locate the batteries, open both hoods, and remove any plastic caps from the battery terminals to expose them. 
4. Keep the jumper cables separate to prevent a short circuit. 

Connecting the Cables

1. Connect the red (positive) clamp: to the positive (+) terminal of the dead battery. 
2. Connect the other red (positive) clamp: to the positive (+) terminal of the good battery. 
3. Connect the black (negative) clamp: to the negative (-) terminal of the good battery. 
4. Connect the final black (negative) clamp: to an unpainted, non-moving metal surface on the engine block or frame of the car with the dead battery. 

Starting the Cars

1. Start the engine: of the car with the good battery. 
2. Wait a few minutes: for the good battery to charge the dead one. 
3. Start the engine: of the car with the dead battery. 
4. If the car doesn’t start, wait a few more minutes and try again. 

Disconnecting the Cables

1. Remove the black (negative) clamp: from the ground point on the dead car. 
2. Remove the black (negative) clamp: from the good battery. 
3. Remove the red (positive) clamp: from the good battery. 
4. Remove the final red (positive) clamp: from the dead battery. 

After the Jump

• Keep the jump-started car running for at least 10-20 minutes to allow the alternator to charge the battery before turning it off. 
• A jump start is often a temporary fix; consider having your battery and charging system checked. 

What is the order of jumpstart?

Connect the red clamp to the positive post on the dead battery. Connect the other red clamp to the positive post on the working battery. Connect the black clamp to the negative post on the working battery. Connect the last black clamp to an unpainted metal surface of your car.

What is the proper way to jumpstart a dead battery?

First we’ll hook our positive cable onto. The positive see the red cable mixed with the red. One. We’ll hook our negative cable onto the negative battery terminal.

How to use a jump starter step by step?

Then take the black or negative end and connect it to a mounting bolt. Then just hit the on switch give that key another twist.