Chevrolet Repair: 1996 S10 sonoma 4X4 trouble, vacuum modulator, vacuum switch

Question
When I put the truck in 4 low or hi the lights change but it is still in 2 wheel. I changed the vacuum modulator but still it hasn't changed. How many things can effect the shifting.

Answer
HI HIENZ,THIS IS MORE THEN LIKELY A TRANSFER CASE SWITCHING MOTOR PROBLEM IF YOU DO NOT HAVE MANUAL TRASFER CASE LOCK IN ..IT IS A LITTLE ELECTRIC MOTOR ON THE BACK SIDE OF THE TRANSFER CASE..IF YOU HAD A SCAN TOOL YOU COULD COMMAND IT ON AND CK FOR POWER DOWN AT THE MOTOR..THIS IS A VERY COMMON PROBLEM...IF YOU HAVE A MANUAL SHIFT THERE WILL BE A CABLE FROM THE TRANSFER CASE TO THE FRONT AXLE THAT LOCKS THE AXLES TOGETHER WHEN THE VACUUM SWITCH CLOSES AND LOCKS IN THE AXLES. THE ELECTRIC MOTOR DOES THE SAME THING ONLY THROUGH THE MOTOR WITH THE FLIP OF A SWITCH...HOPE THIS HELPS YOU AND LET ME KNOW IF YOU NEED MORE INFO,,,TOM..