Diagnosing And Repairing Common Turn Signal Problems:

Diagnosing And Repairing Common Turn Signal Problems

In this article, we will help you in diagnosing and repairing common turn signal problems. Anyone who drives regularly will acknowledge the importance of a turn signal. These lights inform other drivers where you’re going and help you understand where other drivers will turn next. Thus, they play a crucial role in mitigating road accidents. However, what happens if the turn signal in your car starts malfunctioning? One common problem is that the turn signal starts flashing very slowly. When this happens, you need to check whether the car’s battery and the alternator are completely charged or not. Several other issues can hinder the turn signal’s functionality. So, read more and find out!

Diagnosing and Repairing Common Turn Signal Problems

Diagnosing and repairing common turn signal problems can often get complicated primarily because most similar car instruments share the same circuit of wires. Some common problems that cause the turn signal light to malfunction involve relays, fuses, faulty wirings, etc. However, the good thing is that any car owner can easily and completely independently solve these problems. They need the replacement parts, test lights, and a digital multimeter.

Following are some of the most common and recurring turn signal problems, along with the appropriate method of repairing and diagnosing them.

One turn signal works while the other doesn’t

One of the most common problems is that one of them stops working. To solve this problem, follow these steps:

  • The first step is bulb checking. You can access the front light from the engine compartment, whereas the rear light can be accessed from the trunk. Accessing turn lights may differ in certain cars depending on their make and model. To know the exact way, refer to your car’s manual.
  • Turn signal lights are commonly made of two filaments. If either one of the filaments stops working or the bulb glass becomes dark, the turn signal light can malfunction. In such instances, you will have to replace the bulb with a bulb of the same wattage.
  • You should also inspect the bulb for any signs of rust or corrosion. In addition, also check all the power connections and socket ground.

Another variation of this problem is when the dash indicator works, but the turn light doesn’t. This can happen due to a fault in the switch, faulty connector, or a bad turn signal switch.

  • Start by checking the bulb for damaged filaments or dark spots.
  • Then, look for signs of damage or rust on the sockets. Also, check if the power and ground connections are functioning properly.
  • Inspect the flasher relay and look for section X. Now, test the turn signal flasher.
  • Using a digital multimeter or a test light, check whether the voltage travels to the turn signal from the turn signal’s switch.

When the hazard lights stop working

Turn signal lights and hazard lights are connected to the same circuit. So, when you notice that the turn signal light works but the hazard light doesn’t, then it means that the hazard light flasher has become faulty.

If you notice the flasher unit functioning properly, you need to inspect the fuse. Furthermore, you should also check the turn signal switch for a bad connection. Also, check the circuit connecting the turn signal’s switch to the flasher unit for an open. Lastly, look for signs of a short circuit or an electrical opening on the external light’s wire.

Problem with the turn signal’s flashing rate

Sometimes the turn signal’s lights flash either too fast or too slow. If this happens, then follow these steps to troubleshoot:

  • After changing the flasher, you might’ve installed an incorrect flasher type if you notice this problem.
  • This problem may also occur due to the burning out of one of the light bulbs. Burning out of the light bulb makes the turn signal light flash faster. In this case, you’ll have to replace the light bulb.
  • If the turn light flashes slowly, then it means that either your car’s battery needs to be recharged or the alternator is undercharged.

Turn Signal light doesn’t illuminate at all.

When it comes to diagnosing and repairing common turn signal problems, the turn signal light not illuminating to flashing at all will be the most complicated to troubleshoot.

This problem is highly likely due to a poor signal relay. Furthermore, in many vehicles, one relay is used to illuminate the turn lights while the other is used to power the hazard light. You need to troubleshoot both of them.

If your turn signal light doesn’t flash at all due to a damaged or faulty relay, then you’ll have to replace it by following the mentioned steps:

  • To locate the relay, refer to your car’s instruction manual. Most relays are placed underneath the footwell’s dash. If the manual isn’t of any help, consult a car technician.
  • Once you’ve located where the relay is, pull it out. Now replace the old one with a new relay that’s most suitable and compatible with your car. In addition, mark the alignments before pulling the relay out to don’t replace it the other way round.

A turn signal can also stop flashing due to a circuit’s blown  fuse. Since car lights share the same circuit, diagnosing the problem can be tricky. In this case, you will have to perform a circuit check.

  • Firstly, look for loose connections. Also, check the circuit for corrosion and rust.
  • Inspect whether there was a poor connection between the flasher and turn signal switch or between the ignition and flasher.
  • Lastly, check the circuit and turn the signal’s switch for an electrical opening.

The dash’s turn indicator doesn’t flash.


When the instrument panel’s indicator light lights up but doesn’t flash, there is a problem with the turn signal light. This can happen due to a faulty flasher unit.

Inspect the bulb and its socket for signs of rust and damage. You may also have a bad ground so check the socket for that issue. In addition, look for any open present between the circuit connecting the turn signal switch and the problematic light.


Having a functional turn signal is crucial for a safe driving experience. Not just for you but everyone on the road. Therefore, as a driver, you need to educate yourself on the art of diagnosing and repairing common turn signal problems. You will be doing yourself and everyone on the road a favor!