I have a 2002 ford expedition that has a problem with the turn signals. when you turn on the right signal it works properly, but when you turn on the left signal both signals on the back of the vehicle flash along with the light at the top of the tailgate. have been to three garages and they can't find the problem. thanks

Get a wiring diagram from the Free portion of the Autozone site. It is a little work to separate the Help categories at the bottom of their Webpage.

I have heard of SOME 4-way flashers that are built into the turn stalks causing problems. The contact pins for the turn signals are shared as 4-way flasher pins. Try clicking the 4-way flashers off/on about 20 times and then use the left turn signal. It has been known to reseat the contact pins.

The wiring diagram I mentioned would show where the tailgate top light gets its power. One feed should go to the brake light switch for the brakes and another feed should be the flasher feed.

As I see it, you have 2 extra lights going on when you use the left turn signal. Those 2 lights are the tailgate light and right turn signal. The wiring diagram should show the places where the wires are close enough to cross. I am thinking the 4-way flasher is the only place where the top tailgate light gets flasher power; the rest of the time the tailgate light is a Brake light.

I do not want to spend your money on an unnecessary turnstalk and that is why I say to look at a wiring diagram and see if there is anyplace where the wires could cross.

Last, trailer hitch plug. All wires are bundled with left turn, right turn, and brake light in the trailer hitch plug. Corrosion could connect the terminals.

Would like to know what you found.