Try this link, It was to do with powering cameras, but if the Power requirement of the GPS is not above what Kev advises you could use it.

http://www.xt660.com/showthread.php?...hlight=cameras


Colin

Just thought, what I have done in the past when The power requirements are too high for the circuit I used the circuit to trigger power through a relay that was fead directly from the Battery (Through an inline fuse).