Stumped by some trailer lights

[cwcarpenter98]

So I put a trailer hitch and wiring harness on my 95 Dodge Dakota this week. Went to test it last night, and ended up having all the lights work except for the blinkers. When using the turn signals on the left or right, the truck and trailer will both blink very fast. Without the trailer hooked up, the turn signals work fine on the Dakota. Tail lights, brake lights, and emergency flashers work as intended when the trailer is hooked up.

I already tried a heavy duty flasher, but that didn't fix it, and I'm getting the correct voltage at the truck side of the trailer connector. I also cleaned the ground on the trailer and the mounting points for the trailer lights. The wiring harness I got for my truck is a plug and play harness.

The weird thing is that the trailer works just fine when hooked up to my dad's 02 Silverado 1500HD. I haven't tried hooking the trailer up to my 63 yet.

I am plain stumped at this point