What was found
LANDING GEAR EXTENDED WHEN LANDING GEAR LEVER WAS MOVED TO THE OFF POSITION DURING THE AFTER TAKE CHECK LIST. RAN THE GEAR DISAGREE QRH AND GEAR RETRACTED NORMALLY. LANDING GEAR LEVER WAS LEFT IN THE UP POSITION IN ACORDANCE TO THE CHECKLIST. GROUNDED - YES. DIVERSION TIME 30 MINUTES - REMOVED AND REPLACED LANDING GEAR CONTROL LEVER MODULE, REF B737-800 AMM 32-31-11. OPS CHECK GOOD REF AMM 32-31-11 OPS CHECK GOOD. ACCOMPLISHED CONFIRMATION OF REPAIR REF B737-800 FIM TASK 32-30 TASK 809 ALL CHECKS GOOD.