FLC OF MLG MISSED CARGO DOOR LIGHT ON PRE TAXI CHKLIST.

Narrative

PREFLT AND ENG STARTS NORMAL. ACCOMPLISHED ALL CHKLISTS. CLRED FOR ENG START BY GND CREW. STARTED L ENG ONLY TO SAVE FUEL. PERFORMED AFTER START CHKLIST. TAXIED TO RWY 21. SEVERAL MINS LATER STARTED R ENG; PERFORMING DELAYED ENG START AND AFTER START CHKLISTS. THEN ACCOMPLISHED BEFORE TKOF CHKLIST; DURING WHICH WE WERE CLRED FOR TKOF. WHILE TAXIING ONTO THE RWY; WE WERE JUST COMPLETING BEFORE TKOF CHKLIST; SECOND TO LAST ITEM BEING 'ANNUNCIATOR PANEL' GLANCING UP; I WAS STARTLED TO SEE A 'FORWARD CARGO DOOR' LIGHT ILLUMINATED. TAXIED OFF RWY; CALLED COMPANY ON RADIO; REQUESTED THEY SEND SOMEONE OUT TO LOOK AT THE AIRPLANE. AFTER SEVERAL MINS A TRUCK PULLED UP. THEY FOUND THE FORWARD CARGO DOOR AJAR. CLOSED DOOR; LIGHT WENT OUT; FLT CONTINUED NORMALLY. I OBSERVE THE FOLLOWING: THE TENDENCY TO REPEAT CHKLIST RESPONSES BY ROTE WITHOUT THOROUGHLY CHKING EACH ITEM. SETTING SUN AT OUR BACK ON TAXI OUT BLANKETED THE ANNUNCIATOR PANEL WITH LIGHT; MAKING IT DIFFICULT TO SEE INDIVIDUAL LIGHTS ON THE PANEL. DOUBLECHKING AND CLOSELY FOLLOWING CHKLISTS DID; IN THE END; SAVE THE DAY. IN THE FUTURE; I'LL VOW TO BE 100 PERCENT SURE ALL DOOR LIGHTS ARE OUT BEFORE MOVING THE ACFT FROM THE GATE. AND DOUBLECHK IT!