Turn Signal

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Drivers side turn signal works fine. Replaced all bulbs on passengers side but still no turn signal. Emergency flashers work on the drivers side but not passengers either. I do have a trailer wiring harness that is frayed. Sugestions?

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Monday, May 27th, 2013 AT 2:39 PM

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  • 29,776 POSTS

Obviously you want to fix any frayed wires first. No sense searching for some other problem when one is staring you in the face.

There's a couple of ways to approach this. We never like to throw random parts at a problem but if you were inclined to do that, head to a pick-your-own parts salvage yard and get a multifunction switch and combination flasher to try.

As a professional I would perform some tests to determine what is the best suspect. First remove the trim covers so you can get to the wiring connector on the multifunction switch. You'll want to back-probe two wires. Look for the 22 gauge light blue / white wire. Measure the voltage on it with the ignition switch turned on. That's for the left signal. Now you know what normal is. Typically it will have 5.0 volts or 12 volts. That voltage should go to 0 volts when you switch to the left turn signal.

Now compare that to the right signal. Back-probe the light blue / yellow wire. That one must have the same voltage and it must also go to 0 volts when the right signal is turned on. If the voltage is there but it doesn't go to 0 volts, suspect that switch. If there's no voltage there, suspect the combination flasher.

I suspect you're going to find those tests okay because if there was a switch problem the right signals would work with the hazard flashers. If you never see the right signal indicator on the dash, the combination flasher is the main suspect.

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Monday, May 27th, 2013 AT 8:58 PM

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