What was found
"FEEL DIFF PRESS" LIGHT AND "SPEED BRAKE DO NOT ARM" LIGHT ILLUMINATED ON TAKEOFF. HYD PRESSURES NORMAL. GROUNDED - YES. AIR TURNBACK - CREW REPORTED HE FELT A MOMENTARY BUMP BUT WHEN HE CHECKED THE HYDRAULIC PRESSURE INDICATOR IT WAS NORMAL. DUPLICATED PROBLEM WITH PSEU IN AIRMODE AND S1131 DEACTIVATED. RMVD & RPLCD SPEED BRAKE GND SENSOR S1131 REF B737-900 AMM 27-62-61-000-804/-400-809. OPS NML REF AMM 27-62-61. AIRCRAFT JACKED AND VERIFIED SPEED BRAKE GND PROX SNSR S1131 MOVES TO "FAR" ARMED SPEED BRAKES IN AIR. NO FEEL DIFF LT OR SPD BRK DO NOT ARM LT. DOWNJACKED A/C AND VERIFIED SPD BRAKE LTS/ FEEL DIFF LT REMAIN OUT. ACCOMPLISHED AUTOSTOW ACTUATOR GROUND TEST NO DEFECTS NOTED. ACTIVATED AUTOSPEED BRAKES HIGHSPEED SIM. NO DEFECTS NOTED. 4 EA CBS PULLED/TAGGED AND RESET. SPD BRAKE OP CHK GOOD. REF AMM 27-62-61 & 27-62-61-720-801.