Turn signals that do not flash, flash too fast or work only on one side are common on older cars. On an R107, the fault is usually a bulb, a socket, the flasher relay or the combination switch.
Fast flashing
If one side flashes fast, a bulb on that side has failed or is not grounding properly. Check the front, rear and side marker bulbs on that side. Corroded sockets and bad grounds are common at the rear.
No flashing on either side
- Check the turn signal fuse.
- Check the flasher relay.
- Check the hazard switch, since on many cars the turn signals pass through it.
Flasher relay location
The flasher relay location varies by year. On many R107s it is under the dash or integrated with the hazard switch area. Check the wiring diagram for your year. When the relay fails, the signals do not flash at all or stay on solid.
Combination switch
The turn signal lever is part of the combination switch on the steering column. A worn switch can cause signals to work only on one side or only intermittently. It can also affect the high beams, flash-to-pass and wipers. Replacing the combination switch requires removing the steering column covers.
Bulbs and sockets
- Remove the lens or bulb holder.
- Check the bulb filament.
- Check the socket for corrosion. Clean it with a small brush or contact cleaner.
- Check the ground. Many rear bulb holders ground through a strip on the holder.
- Use the correct bulb type for each position. A wrong bulb can make the flasher relay flash at the wrong speed.
Hazard switch
If the hazard lights work but the turn signals do not, the hazard switch may still be the problem, since the turn signal current often passes through it. The hazard switch is in the center of the dash on many cars. Cleaning the contacts sometimes fixes it; otherwise replace it.
LED conversion
If you fit LED bulbs, the flasher relay may flash too fast because the load is lower. Use an LED-compatible flasher relay or load resistors.
Quick answers
- Why do my signals stay on solid? Usually the flasher relay.
- Why do signals work only with the hazard switch on? The turn signal path through the hazard switch or the combination switch.
- Can a bad tail light affect turn signals? Yes, a shared ground can.
- Where do I find the diagram? See electrical troubleshooting.
