I am having this same problem mine. It comes on and go's off randomly sometimes it flashes some times it is solid.

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02 Ranger XLT 4x4 Off Road, 4.0L SOHC, Automatic, 8.8 4.10 LS, Super-Cab, alpine digital media center, Rockford Fosgate 600w mono block, Rockford Fosgate 10" sub woofer, Alpine components front and rear.