Tim, a bad ground will cause your turn signals to flash the side marker lights. 99% of trailer light problems are a faulty ground. Be suspect of the dealer installed harness and check the ground... sometimes they don't even get hooked up at all. Take a spare wire and run it temporarily from a ground on your truck frame to the mounting bolt of the tail-light to check this. If you have a meter, check the resistance between that wire and each bulb ground and harness ground to track down the failure... Running a wire ground on long trailers or old, rusty trailers is often necessary.
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<br>If you are cross-wired, ignore all of the previous advice.<br><br>Mike Teets
<br>Dublin, Ohio
<br>I20 #246
<br>M4.3 #59