TM 10-3930-669-20 WARNING · High-pressure   hydraulics   [oil   under   3,000   psi   (20,700   kPa)   pressure]   operate   this equipment.    Refer  to  vehicle  operator  and  maintenance  manuals  for  hydraulic  oil pressure.  Never disconnect any hydraulic line or fitting without first dropping pressure to zero.  Failure to comply may result in injury to personnel. · Hydraulic oil is slippery and can cause falls.  To avoid injury, wipe up spilled oil with rags. PRESSURE TEST (1) Remove  test  port  plug  and  connect a   0   to   4,000   psi   (0-27,567   kPa) pressure gauge to PRIMARY PUMP PRESSURE test port. (2) Start engine (TM 10-3930-669-10). (3) With   aid   of   an   assistant,   operate any  hydraulic  control  and  observe pressure gauge. (a) If  2,000  to  2,600  psi  (13,780- 17,920 kPa) are not measured,  perform  Steps  (4) and   (5)   below   and   replace priority valve (Para 17-11). (b) If  2,000  to  2,600  psi  (13,780- 17,920   kPa)   are   measured, priority valve is OK. (4) Shut down engine. (5) Remove pressure gauge from PRIMARY  PUMP  PRESSURE  test port and install test port plug. (6) Install cab (Para 15-2). 2-447