What was found
FLIGHT 4550 FWA-PIT. DURING TAXIING FROM GATE THE AUTOCOARSEN CAUTION LIGHT ILLUMINATED AFTER THE AUTOCOARSEN SYSTEM WAS SELECTED ON. A/C RETURNED TO GATE AND WAS TAKEN OUT OF SERVICE AT 0500 4-24-03. FLIGHTS SWAPPED TO A/C 101CN. DURING TROUBLESHOOTING FWA MX FOUND THE CANNON PLUG BETWEEN THE LH P3 SWITCH & 161VP P8 LOOSE. FWA MX RESEATED THE SAME CONNECTOR, PERFORMED GROUND RUNS FOR OPERATIONAL CHECKS OF THE AUTOCOARSENING SYSTEM. OPERATIONAL CHECKS WERE SATISFACTORY. A/C RETURNED TO SERVICE AT 1646 4-24-03.