A rear facing light bar assembly that incorporates a plurality of light functions in a small integrated unit. A multifunctional circuit board powers different colored light emitting diodes to produce the tail light, brake light, amber and/or backup light. The assembly also has end caps, a one-piece polycarbonate tube lens and an extruded housing. Heat from the circuit board is dissipated through the end caps and into the extruded housing. The assembly is constructed such that the electronics are completely protected from the outside environment, and sealed from water and dust intrusion. The light also minimizes tooling and assembly cost, yet provides a secure seal protecting the electrical components. In addition, the light is serviceable so individual parts can be replaced or repaired if parts are damaged.