Turn Signals Not Working

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How to Diagnose Turn Signals Not Working

Blinkers or turn signals help communicate our intended vehicle direction. By activating the turn signal switch you are able to alert people around your vehicle by flashing a light bulb at the front and rear of the vehicle. Turn signals first appeared on vehicles in 1939 and since then have become standard equipment for all vehicles. The turn signal system is operated by a turn signal switch, which can activate either the right or left side blinker. The bulbs at the front and back of the vehicle are connected to the switch.

 Ford had a common problem that would cause the blinker operation to fail caused by a short circuit in the turn signal switch. The switch contact plate will come loose causing the blinkers to stay on or not work at all. To replace this switch remove the steering column cover (3 screws on the bottom facing upward). Once the steering column cover is off remove the two mounting screws that attach the switch to the column. When the switch is loose from the column remove the wiring harness connector and reconnect to the new switch. 

Remount the new switch with the mounting screws and re-attach the steering wheel column cover and recheck operation. The turn signal lights in your car are a basic electrical system that controls the front and rear blinker lights to alert the intended direction of the vehicle. We have listed some of the most common problems and repair troubleshooting tips below:

Troubleshooting Procedure

Step 1 - Turn the key to the on position (do not start engine)

Step 2 - Inspect the system fuse located in the fuse panel and replace if needed. If you cannot find the location of the blinker fuse consult your owner's manual or an online repair manual.

Step 3 - When a blinker flasher fails it can cause blinker lights to say on, not blink, or not go on at all. To test the blinker system flasher, remove the flasher unit and insert a jumper wire between the two terminals. If blinker stays on in both directions without blinking, replace the flasher. If you cannot find the location of the blinker flasher consult your owners manual or an online repair manual.

Step 4 - If both test results are positive the turn signal switch has probably failed and replacement is required. There is a possibility that the system has a bad ground but this condition is rare.

Step 5 - A flasher unit is incorporated into the system and is used to break and reconnect the circuit; this device is what creates the blinking operation. If the blinker system flashes quickly on one side or the other, a bulb has failed somewhere in the system. Inspect all bulbs and replace as needed, then recheck the system. If you have replaced the bulb but it still blinks fast and the bulb does not illuminate properly the ground circuit inside the bulb socket has failed and replacement is required.

If further assistance is needed, our certified car repair technicians are ready to answer your car questions.

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Written by
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35 years in the automotive repair field, ASE Master Technician, Advanced Electrical and Mechanical Theory.


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Article first published (Updated 2013-08-16)