CL65 CREW HAD ERRATIC LOC AND GS POSSIBLY CAUSED BY PAX CELL PHONE USE.

Narrative

WE WERE IN THE CLOUDS AND ON A VECTOR FROM CHICAGO APCH CTLR TO JOIN THE LOCALIZER FOR RWY 22L AT ORD. BOTH NAV RADIOS HAD BEEN TUNED TO 110.1 AND THE IDENTIFIER (ILQQ) HAD BEEN RECEIVED. AS WE WERE FLYING TOWARD THE COURSE; BOTH THE CAPT'S AND FO'S CDI'S BEGAN TO WAVER BETWEEN FULL SCALE AND 'FLY RIGHT' AND FULL SCALE 'FLY LEFT' INDICATIONS. OUR DISPLAYS ALSO SHOWED INTERMITTENT LOC AND GS RED FLAGS. WE WANTED TO QUERY ATC ABOUT THE INTEGRITY OF THE 22L LOC; BUT THE CTLR WAS TALKING NON-STOP AND WE COULD NOT GET HIS ATTENTION. I WAS CONSIDERING EXECUTING A MISSED APCH WHEN THE CTLR CALLED AND ASKED US IF WE WERE RECEIVING THE LOCALIZER. WE ANSWERED THAT OUR CDI'S WERE WAVERING. THE CTLR BROKE US OFF THE APCH AND GAVE US VECTORS AROUND FOR A SECOND APCH. THE SECOND APCH TO RWY 22L WAS UNEVENTFUL AND ALL INDICATIONS WERE NORMAL. AFTER DEPLANING THE PAX AT THE GATE; WE DISCUSSED WHAT HAD HAPPENED WITH THE FLT ATTENDANT. THE FLT ATTENDANT STATED THAT; DURING HER FINAL WALK THROUGH THE CABIN BEFORE LANDING; SHE HAD TO ASK A PAX TO TURN OFF A CELL PHONE THAT HE WAS USING. BY MY ESTIMATION; THE TIME THAT THE FLT ATTENDANT SAID SHE SAW THE PAX USING HIS CELL PHONE CORRELATES APPROX TO THE TIME WE WERE RECEIVING THE FAULTY LOCALIZER COURSE INDICATIONS DURING THE FIRST APCH.