What was found
(CAN) AFTER TAKEOFF OUT OF YWG, A/C WOULD NOT PRESSURIZE. NON NORMAL AUTO-FAIL CHECKLIST EXECUTED BUT DID NOT CORRECT PROBLEM. A/C LEVELED OFF AT 9,000 FT AND RETURN TO BASE. LANDED IN YWG W/O INCIDENT. MAINTENANCE INSPECTION DISCOVERED E/E SERVICE DOOR OPEN AND DOOR WARNING LIGHT UNSERVICABLE. MAINT FOUND BROKEN WIRE TERMINAL ON E/E DOOR WARNING SWITCH. WIRE REPLACED IAW MM 52-71-00 AND GROUND CHECKED SERVICEABLE. SERVICE DOOR CLOSED AND RETURNED TO SERVICE WITH NO FURTHER INCIDENTS TO REPORT.