How to Troubleshoot a Turn Signal Switch

If the turn signal lights on your vehicle dont work at all or behave strangely and you already inspected light bulbs, sockets, circuit, fuse and flasher unit, it is time to troubleshoot the turn signal switch. These switches are subject to wear as well and eventually fail. If you have a basic knowledge of electricity or want to learn basic troubleshooting procedures, the next steps will help you determine effectively whether the turn signal switch on your vehicle needs replacement. Work along with the wiring diagram located in your vehicle service manual, as circuits and configurations vary from model to model.

Instructions

1

Remove the dashboard lower cover and knee bolster (under the steering column) so you have access to the switch wiring. You might have to take off the upper and lower steering column covers too in order to reach the wire connectors for the turn signal switch.

2

Look at the wiring diagram for your vehicle and find the wire carrying current from the turn signal flasher to the turn signal switch. Locate this wire in your vehicle.

3

Turn on the right turn signal.

4

Use a test light to probe the backside of the wire connector you located in Step 2. If the test light does not flash, locate the open in the circuit between the car battery and the turn signal switch. If the test light flashes, proceed to the next steps.

5

Look at the wiring diagram for your vehicle and find the wires carrying current from the turn signal switch to the turn signal lights. Locate these wires in your vehicle.

6

Turn on the right turn signal.

7

Use a test light to probe the back side of the wire connectors you located in step 5. The test light should flash as you probe the connector carrying current to the right turn signal, but not at the connector carrying current to the left turn signal.

8

Turn on the left turn signal.

9

Repeat Step 7. This time, the test light should flash as you probe the connector carrying current to the left turn signal, but not at the connector carrying current to the right turn signal.

10

Replace the switch if it failed tests in Steps 7 and 9.