Cusser
+1y
Great catch by Earl, about a trailer light hook-up being involved. Glad it's solved now.
For me, above: it was a bad AC idler pulley on that Frontier, it can apparently go on either way, and there's a 1mm offset, and the pulley is not marked with paint or metal stamp, no instructions, nothing in factory service manual, and different pulley design that original; so if I got the first pulley reversed (don't know) and manufacturer had to "eat" the warranty because of no markings/instruction, then I don't feel bad.