Chris K
Junior Member
I replaced the alternator on my 07 QC 5.7L 4x4 today with the higher output Napa replacement( there are 2 versions one has a higher amperage output). The only difference is the housing is slightly smaller and the 2 prong plug is located facing up instead of sideways....... Everything plugged in and bolted up fine. But after returning from the store to drop off the alternator core I realized my brake lights would not turn off and my trailer brake controller wasnt working at all. I pulled the neg battery cable and lights remained lit. I then pulled the fuse for the lights and still they stayed on. Finally I disconnected the alternator and the lights went out. I then reconnected alternator and battery cable and checked the lights. They are working normally now as is the trailer brake controller. My only concern is the 2 prong plug on the alternator doesnt seem to lock in as tight as I think it should, is it possible that for some weird reason, the brake light circuit runs through the alternator??? Also maybe the higher amperage alternator isn't interchangeable with the lower amp one??
