I am new here and i have a quick question. well here goes. first off i have a 96 LS with 4WD. whsn i start the car it runs fine. the 2 wheel hi works fine when i go to shift into 4 wheel hi the 4Hi light flashes 2 or 3 times and goes back to 2Hi. i can here a click but it will not engage. now if i go to nuetral and push 4low it goes to 4low but the light does not light. i am wondering if it is the switch in the dash or something else. any info on this would help greatly. thanks in advance.

 

check your vacuum actuator for leaks or tears
they go bad and cause the truck not to engage the front differential
btw it should be under the battery box