What Causes the Hazard Lights to Work but Turn Signals Not to Work?
4 Answers
This situation is generally caused by two reasons: either the flasher relay is damaged, or the turn signal fuse has blown. The former can be replaced by yourself, while the latter requires careful inspection of the turn signal circuit for any short circuits before replacing the turn signal fuse circuit. Checking the Relay: Check if there is power at the live wire terminal of the flasher relay. If there is no power, inspect whether the wire to the power source is broken. Connecting the Terminals: Use a screwdriver to connect the two terminals of the flasher relay. If the turn signals light up, it indicates a fault with the flasher relay, which should be replaced. If they do not light up, inspect the flasher relay. Open the flasher relay cover and check if the coil and resistor are intact. If the resistor heats up but the contacts cannot close, press the movable contact; if the turn signals light up, it indicates a relay fault. Adjust if the contact gap is too large. If pressing the movable contact to close the contacts still does not light the turn signals, use a screwdriver to short-circuit the contacts. If the lights then turn on, it indicates oxidized contacts.
I've seen quite a few cases where the turn signals don't work but the hazard lights do in cars that have been driven for over a decade. The most likely cause is burnt or oxidized metal contacts inside the turn signal switch, preventing the signal from the steering column lever from getting through. Sometimes, a partial failure in the turn signal function of the flasher relay can also cause this, even though the hazard lights still work. Another possibility is that the turn signal fuse has blown individually, which can be checked in the steering column fuse box. Additionally, loose wiring connections causing poor contact are a common cause, especially in the densely wired area under the steering wheel. Since turn signals are crucial for driving safety, it's important to promptly visit an auto repair shop to diagnose the issue when this happens. Never risk driving under such conditions to avoid rear-end collisions when changing lanes.
As a mechanic who frequently deals with automotive electrical circuits, I believe the issue primarily lies in the control components. The turn signals and hazard warning lights share the same bulbs but operate on independent circuits. Since the hazard lights work, it indicates the bulbs themselves are functioning properly, so the fault must be in the turn signal control system. The most common issue is wear on the turn signal switch contacts—opening the combination switch will reveal burn marks on the copper contact strips. Inside the flasher relay, two sets of contacts separately handle the turn signals and hazard warnings; if the turn signal side contacts are burnt out, it can also cause abnormalities. Additionally, a blown dedicated fuse for the turn signals can lead to this issue—when replacing it, be sure to use a fuse with the same amperage rating. Aging or broken wiring is another hidden factor; I recommend using a multimeter to check the continuity of the turn signal signal lines.
I remember my car had the same issue last year, the hazard lights were flashing normally but the turn signals didn't respond. The mechanic explained that the contact points of the turn signal lever switch under the steering wheel were dirty, and cleaning them with alcohol solved the problem. He said many older cars experience this symptom, either due to internal wear of the switch or a blown turn signal fuse. Just spending a little over ten dollars to replace a new fuse would fix it. Of course, partial damage to the flasher relay also needs to be considered, since the set of contacts controlling the turn signals is separate from those for the hazard warning. Although this kind of problem isn't urgent, changing lanes without turn signals is very dangerous, so it's recommended to visit a nearby auto repair shop as soon as you notice it.
