What is the reason for the hazard lights not working while the turn signals are functioning normally?
4 Answers
The hazard lights not working while the turn signals are functioning normally could be due to a blown fuse or a burnt-out bulb. Below are the relevant explanations: 1. Car Fuse: There are many electrical devices in a car's circuit connected by wires of different colors, among which the most important should be the fuse. The fuse is a customary term, referred to as a circuit breaker in national standards. The role of the fuse is to protect the circuit (wiring) and electrical equipment. 2. Bulb: Try turning on the hazard light switch to see if the lights come on. If they do, the problem lies in the turn signal switch part. If they don't, check if all four turn signals are not working. If the issue is with the bulbs, it is generally unlikely that all four bulbs (front, rear, left, right) would fail simultaneously.
Last time my car also had the issue where the hazard lights wouldn't work, though the turn signals were functioning normally. It turned out to be a blown fuse. The hazard lights and turn signals share the same bulbs, but their circuits are separate. The hazard lights are mainly controlled by the flasher relay, which is hidden under the steering wheel or in the fuse box. You can start by tapping the hazard light switch a couple of times—sometimes poor contact can suddenly fix itself. If that doesn’t work, check the 15A fuse labeled 'Hazard Warning Lights' in the fuse box; pull it out and see if the metal wire inside is broken. Next, inspect the hazard light switch itself—oxidized contacts can also cause poor connection. The worst-case scenario is a faulty body control module, which requires a computer diagnostic. I strongly recommend fixing the hazard lights ASAP—driving without them in rain or fog is extremely dangerous.
Having worked in auto repair for over a decade, it's common to see hazard lights malfunction while turn signals work normally. Most cases involve a failed hazard flasher relay - this small box controls current frequency. Turn signals are directly controlled by the combination switch, hence their normal operation. You can locate the hazard relay in the fuse box, swap it with the horn relay for testing - if the horn sounds, the original relay is faulty. Check for loose body wiring harness connections, especially under the dashboard where wires often get pulled loose. For vehicles with automatic alarm systems, note that anti-theft module failures can also disable hazard lights. Use a multimeter to test voltage on hazard switch signal wires - if there's no voltage change when pressing the switch, the switch assembly needs replacement.
Although the hazard lights and turn signals use the same set of bulbs, their control logic is completely different. Turn signals are directly controlled by a physical switch, while hazard lights require the involvement of the BCM (Body Control Module). The troubleshooting tree for non-functional hazard lights is quite clear: first check the hazard light switch, then the fuse, followed by the relay, and finally the BCM. For vehicles equipped with automatic power cut-off, be aware that some models may lock the hazard light function after an accident-induced power cut, requiring reactivation. During self-inspection, pay special attention to any signs of burning on the relay pins—black scorch marks indicate a short circuit. For vehicles with modified central control systems, it's crucial to check if the hazard light control wire was mistakenly cut. I've encountered cases where workers incorrectly cut wiring harnesses while installing navigation systems.
