Check the brake lights at the top of the window. I had the same problem when I bought mine.
2003 Dodge CTD Quad Cab 4x4, 320k miles and counting
98 ZJ Limited, 5.2L, NP242, Jet Stage II (worthless), K&N, 245/75-16 BFG KO's
89 XJ, stock
79 CJ7 - Options included ripped soft top, leaky 4.2L (5qts/week), ripped seats, 33" tires, bondo & gray primer