Take the bulb out and go get you a 1157 and put back in there. That will fix the battery light problem more than likely. just because a bulb fits in a ocket doesnt' mean it will work. You got to put back what you took out. ON the light issue. check all connections around the tailights, take them apart and make sure they aren't corroded and such, if they are then clean them and dab some dielctric grease on 'em to help keep the water off your terminals. If everything looks good back there, then start tracing the wires back up the trailer until you find one thats rubbed, kinked, pinched, whatever. You're going to find something. It may be a loose ground. A test light would be good to help you figure it out as well. Also check the plug that pulgs into your truck and make sure all that is good and not corroded or mashed. good luck!