What was found
ENROUTE, FLIGHT CREW RECEIVED A WEIGHT ON WHEELS AND A PROXIMITY SENSOR FAIL CAS MESSAGE. REFERENCED QRH AND CONTACTED MAINTENANCE CONTROL. IT WAS DETERMINED THAT NORMAL GROUND SPOILER, NOSE WHEEL STEERING, AND NORMAL BRAKING COULD BE COMPROMISED AFTER TOUCHDOWN. THE DECISION WAS MADE TO DIVERT DUE TO LONGER RUNWAYS AND AN EMERGENCY WAS DECLARED. LANDED WITHOUT INCIDENT AND THE ONLY SYS FAILURE WAS GROUND SPOILER DEPLOYMENT. FLIGHT SPOILERS WERE SELECTED TO THE EMERGENCY POSITION AFTER TOUCHDOWN BUT DID NOT RESPOND. THE PROXIMITY SENSOR ELECTRONIC UNIT HAD FAILED. A TESTED AND INSPECTED UNIT WAS INSTALLED. OPS CHECKED NORMAL AND ACFT RETURNED TO SERVICE WITH NO FURTHER FAULTS.