Diagnose Turn Signal Problems

Turn Signals

When diagnosing an electrical circuit, it is important to first make sure that the fuse and relay are working properly. These are the originators of the power for the circuit and the process continues through the circuit from here. The components in a turn signal circuit are the fuse, relay, flasher, turn signal switch, instrument cluster, the turn signal bulbs and sockets or circuit boards themselves.


1. Turn the key to the on position where the lights on the dash are on. There is no need to start the vehicle.

2. Push the turn signal switch in either direction. Note whether the light on the dash blinks or stays lit without blinking. Do the same to the opposite side. If the dash light stays on but does not blink then the problem is with the turn signal flasher, which needs to be replaced. It is located under the dash near the steering column. If the turn signal light on the dash lights up and flashes at a normal rate leave them on and exit the car and check the front and back to see if the bulbs are working. Do the same for the opposite side. If the dash turn signal lights were flashing in either direction most likely one of the bulbs is not lighting and will be located easily.

3. Check the fuse in the fuse block. If the dash turn signal indicators did not illuminate in either direction, there is a power or wiring problem. The fuse box can be found just to the left of the steering column, under the dash or on the side of the dash, facing the door. Both locations will always be on the driver’s side. The access panel is usually well marked. If the fuse was blown just replace it with the same size fuse. If it was not blown go to Step 4.

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4. Turn the emergency flashers on. If the emergency flashers function and the indicator lights on the dash work the turn signal switch is at fault and needs to be replaced.