1986 Ford Bronco Tailgate problems!?

I bought this bronco a while back and have been fixing it up when i bought it non of the windows would roll down... i put new window motors in the front but not in the tailgate....after i got the truck running all the electrical stuff started working again...the rear gl would roll down about 2in and wouldnt go down any further, also when you push the switch up or down the lights will flash/dim and the radio will stop working for like 2 seconds...i took the window motor out of the back and hooked it back up and i can hit the switch and the motor will work put it will still stop after a little while and then it still dims the light and etc. so i figure it is going to be the Tailgate Window switch that is on the dash next to the A/C controls...but i was just wanting to get some opinions before i spend $31 plus shipping... from what i have read there is a key switch i guess when you turn the key it rolls the window down? idk i paid $250 for the truck and it has been a really good bye but it did not come with the door keys but it did come with the ignition key...so i dont know anything about the rear key switch...? just need some opinions like i said before i spend the cash to get a switch that wont work. Please? Thanks.