What was found
(CAN) PILOTS RPTED OUTBOUND THAT CARGO DOOR WARNING LIGHT CAME ON AT 4.4 PSI DIFFERENTIAL. A/C RETURNED & LANDED W/O INCID..MAINT INSP FOUND WIRING ON REAR CARGO DOOR HANDLE SWITCH CHAFED & GROUNDING OUT ON WARNING CCT. WIRING REPD IN ACCORD WITH APPLICABLE STANDARDS OF A/W & A/C DEEMED SERVICEABLE FOR TEST FLT. CARGO DOOR LIGHT CONTINUED TO ILLUMINATE ON TEST FLT - A/C RETURNED TO BASE & LANDED W/O INCID..MAINT REPLD REAR CARGO DOOR HANDLE SWITCH & GROUND PRESSURIZED A/C TO 6.6 PSI DIFFERENTIALWITH NO FAULTS TO RPT. TEST FLT SUCCESSFULLY COMPLETED. A/C RT-SRV WITH NO FURTHER INCID. TO RPT.