What was found
ON TAKEOFF CLIMB, LANDING GEAR FAILED TO RETRACT, TRANSPONDER DID NOT REPORT, CABIN FAILED TO PRESSURIZE. INSPECTED AND FOUND DEFECTIVE LEFT MAIN GEAR SQUAT SWITCH. REMOVED LEFT SQUAT SWITCH AND INSTALLED A NEW UNIT IAW LEAR 60 MM. OPERATIONAL CHECK, GOOD. UNEVENTFUL PRECAUTIONARY LANDING.