What was found
WIRE THAT GOES TO PIN NR 2 AT CONNECTOR DS29105 SHORTED TO GROUND SOMEWHERE, GENERATING THE LOW HYD RSVR PSI MESSAGE. WIRE SHORTED TO SHIELD BETWEEN D7180P AND DS29105. DISASSEMBLED AND DEPINNED BOTH CONNECTORS. STARTED REMOVING WIRE W8144-1002-18. UNABLE TO GAIN ACCESS TO FEED THRU. REMOVED FIRE AGENT LINE AND UNCLAMPED WIRE BUNDLES FOR ACCESS TO FEED THRU FROM BOTTOM OF THE WING. REPLACED WIRE W8144-1002-18 IAW WDM, MESSAGE CLEARED, SYS OP CHECKS NORMAL.