Last month, our customer Jesus purchased a pair of 9006 bulbs for the low forward lighting on his 1999 Jeep Grand Cherokee Laredo 4.0.Several days later, he came back and told us the bulbs were perfect condition but didn’t work, he was quite upset as he already paid the mechanic to install them, so he thought the lights were defective and demanded a refund.We have heard of this issue since we started our business on LED bulbs, the lights are not defective. It is because the positive and negative prongs are opposite to what the car prongs are, all you need to do is reverse the polarity and the bulbs will light up.This customer followed our instruction to reverse the polarity, and the problem solved, he also left good feedback for us.So if the same thing happens on your LED bulbs, please reverse the polarity to make the bulbs work.