Common turn signal problems include burned-out bulbs, faulty flasher units, blown fuses and broken toggle switches. These problems can cause one or more bulbs to fail to turn on to or remain on constantly.
The most common problem is a burned-out bulb, which causes only one inactive signal. If turn signals are lighting up without flashing, the flasher unit might be faulty. The flasher quickly breaks and reconnects the electrical current to turn signals, causing them to flash, and it is usually located near the fuse box. If none of the bulbs are lighting up, drivers should check for blown fuses or a broken switch on the steering column.