Why does the car's hazard lights keep flashing and the engine won't start?

[Palacios]

The reasons why the car's hazard lights keep flashing and the engine won't start are as follows: 1. Hazard lights keep flashing: If the car's hazard lights suddenly start flashing automatically, it is most likely due to a problem with the control box. You need to check if the hazard light relay is functioning properly. Use a multimeter to measure the output line of the hazard light relay to see if there is a 12v output. If there is an intermittent output change, it indicates normal operation. However, if there is no output or a constant 12v output, it means the hazard light relay is damaged and needs to be replaced. It could also be due to abnormal wiring issues, in which case professional assistance is required for troubleshooting. 2. Car won't start: (1) When starting the engine, you only hear the starter solenoid making a 'clicking' sound, or during the first attempt, the starter turns the crankshaft slowly a few times, followed by the starter solenoid making a 'clicking' sound but the crankshaft doesn't rotate. This phenomenon is usually a sign of a 'broken cell' fault in the battery. (2) The car starts every time after a temporary stop, but after a longer parking period or the next day, it only manages to turn the crankshaft once. This indicates severe self-discharge of the battery, with its plates and separators heavily aged, suggesting the battery is nearing the end of its life. (3) During startup, the starter suddenly loses power and there is a smell of burning rubber or smoke coming from the battery area. This is mostly due to poor contact at the terminal posts or clamps, causing overheating and damage.

[LaCora]

A couple of days ago, my car had a similar issue—the hazard lights kept flashing and couldn’t be turned off, plus the engine wouldn’t start. It was incredibly frustrating. Later, I found out the battery was completely dead because the hazard lights drained it too quickly, leaving no power to start the engine. Alternatively, the hazard light switch might have been stuck and couldn’t spring back. As a temporary fix, I pulled the hazard light-related fuse from the fuse box to stop the flashing, but this was just a short-term solution. Ultimately, I had to take it to a repair shop for a full check of the electrical system, including the battery health, wiring connections, and switch condition. To prevent such problems, regularly test your battery’s lifespan and avoid leaving hazard lights on for extended periods while parked. For safety, if a malfunction occurs, first park in a safe area, turn on interior lights to warn other drivers, and avoid repeatedly trying to start the engine to conserve power. If towing isn’t an option, jump-starting might work, but it’s best to seek professional assistance.

[DelKaleb]

From an electrical perspective, this issue is usually caused by common factors leading to both the inability to turn off the hazard lights and the failure to start the engine, such as an aging battery with excessively low voltage that cannot support the system. The hazard light relay may be stuck or malfunctioning, causing continuous flashing, while engine starting requires stable power. Priority should be given to checking whether the battery terminals are loose or corroded, and using a voltmeter to see if the voltage is below 12 volts. If the dashboard lights are dim, it basically confirms a battery problem. Additionally, check if the hazard light fuse is blown, as a short circuit can also cause the lights to stay on. I recommend not attempting to repair complex parts yourself; instead, go to a professional repair shop to scan for trouble codes with diagnostic tools to locate the root of the problem safely and reliably. Regular maintenance should pay attention to battery life, replacing it every three to five years to prevent unexpected incidents.

[VonJulian]

I've also panicked about this before. If the hazard lights won't stop flashing and the car won't start, it's mostly likely caused by a dead battery - the hazard lights drain the battery faster, making it impossible to start the engine. Or maybe a door wasn't closed properly, triggering the anti-theft alarm and causing the lights to flash continuously. I called roadside assistance for a jump start, which usually solves the problem. Safety tip: don't repeatedly try to start the car at this time to avoid further damage. Park in a safe location and have a professional check for switch or wiring issues. For a quick fix, check the fuse box and remove the relevant component to turn off the flashing lights first.