What was found
WHILE ENROUTE TO OMA THE CREW GOT A PROX SYSTEM CAUTION MESSAGE AND RAN THE QRH AND MADE THE DECISION TO RETURN BACK TO CLT. THEY DID DECLARED A EMERGENCY AND TRUCKS DID ROLL, BUT NOT NEED AS THE AIRCRAFT WAS ABLE TO TAXI TO TAXI TO A GATE UNDER THEIR OWN POWER. THEY DID NOT LAND OVERWEIGHT NOR DID THE PASSENGERS BRACE. NO FURTHER INFORMATION GIVEN AT THIS TIME. T/S IAW CRJ 900 FIM 32-32-10-810-803 FOR B CODE 007191. CONTINUITY CHECK GOOD. REPLACED LANDING GEAR SELECTOR VALVE, IAW CRJ 900 AMM 32-32-10-000/400-801. OPERATIONS TESTED, IAW CRJ 900 AMM 32-30-00-710-801 LANDING GEAR EXTENSION/RETRACTION SYSTEM. OPERATIONS CHECK GOOD. NO DEFECTS AT THIS TIME.