Headlights stopped working after jump-starting the car

Symptoms

• Headlights worked before the jump start attempt
• No headlights after successfully starting the car via jump
• Other electronics may show issues too
• Jump start took multiple attempts or cables were connected incorrectly

Likely causes

• CommonBlown fuse from a voltage spike during jump-startingIncorrect connection order or a poor connection during jumping can cause a brief voltage spike that blows a fuse.
• PossibleReversed polarity connection during the jumpConnecting cables backward, even briefly, can damage sensitive electronics and blow fuses.
• PossibleCoincidental unrelated failure discovered at the same timeSometimes a pre-existing issue is simply noticed right after dealing with a dead battery.

What to do

1. Check the fuse box for any blown fuses, particularly ones related to headlights and other electronics.
2. Review how the jump start was performed to check if cables may have been connected in the wrong order or polarity.
3. Test other electronics for similar issues, which can help determine if this is isolated to headlights or more widespread.
4. Replace any blown fuses found with the correct amperage rating.
5. If reversed polarity is suspected, have a shop check for damage to more sensitive components like the alternator or computer modules.
6. Avoid further jump-start attempts until the cause of the current issue is resolved.
7. Have a shop perform a full electrical check if multiple systems seem affected, since reversed polarity can cause broader damage.
8. Be extra careful with cable connection order on any future jump starts: red to dead positive, red to good positive, black to good negative, black to unpainted metal on the dead car.

Tools and parts

• Fuse puller or pliers
• Replacement fuses

When to call a pro

If more than just the headlights seem affected after a jump start, have a shop check for damage from possible reversed polarity or a voltage spike.

Safety