AN MLG ACR ACFT TOOK OFF WITH A CARGO DOOR OPEN. THE CREW HAD NO INDICATION OF THIS. THEY REVISED THEIR CLRNC TO A LOWER ALT AND CONTINUED ON TO THEIR DEST WITHOUT DAMAGE OR INJURY.

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AFTER TKOF; WE EXPERIENCED PRESSURIZATION PROBLEMS. INITIALLY THE CABIN WAS CLBING RAPIDLY. I CHKED BOTH PACKS WERE ON THE POS OF THE CABIN PRESSURE CTLR; I BELIEVE I LOCKED IT; AND SELECTED FULL FORWARD. AT THIS TIME; THE CAPT CHKED THE ANNUNCIATOR PANEL 'PRESS TO TEST LIGHT' AND ALL DOOR LIGHTS CHKED OK. ALL WERE OFF AFTER THE TEST INDICATING ALL DOORS CLOSED AND ALL CIRCUITS CHKED OK WHICH WAS NOT TRUE. THE CAPT DECIDED TO WAIT TILL WE LEVELED AT 10000 FT TO FURTHER TROUBLESHOOT THE SYS. AT 10000 FT WE ACCOMPLISHED THE APPROPRIATE PROC. WE ADVISED ATC WE WOULD LIKE TO PROCEED TO PHL AT 10000 FT. AT 10000 FT WE HAD A CABIN ALT OF 8500 TO 8800 APPROX 0.25 PSI. WE HAD LIMITED CTL OF THE CABIN. BASED ON THE FUEL LOAD OF 19500 POUNDS WHICH GAVE US 6000 POUNDS EXTRA FUEL AND THE GOOD WX IN PHL. WE ELECTED TO CONTINUE TO PHL. WE ADVISED PHL 50 MI OUT THAT WE HAD EXPERIENCED PRESSURIZATION PROBLEMS. AFTER AN UNEVENTFUL LNDG IN PHL; WE WERE INFORMED THAT A CARGO DOOR HAD BEEN FOUND OPEN ON ARR. SUBSEQUENTLY MAINT IN PHL FOUND A DEFECTIVE AFT CARGO DOOR LIGHT SWITCH. THE LIGHT TESTED PROPERLY BUT DID NOT ILLUMINATE WITH THE DOOR OPEN AS IT SHOULD. I BELIEVE MAINT SHOULD BE REQUIRED TO OPERATIONALLY CHK THIS SWITCH BY VISUALLY OPENING AND CLOSING THE DOOR WHILE SOMEONE OBSERVES THE PROPER LIGHT ILLUMINATION MAYBE ONCE A MONTH. WHOEVER MARSHALLS ACFT OFF THE GATE; SHOULD BE REQUIRED TO CHK THE POS OF ALL DOORS AND DOOR HANDLES PRIOR TO WAVE OFF.