2001 Blazer stuck in 4whl. drive high
 

I put my truck in 4whl. drive high last week cant get it back to 2whl. I took the truck to a local trans. shop because the service 4x4 light is on also. Theysay they scanned it, and found that it needed a transfer case control module. So I bought a new one put it in and the truck is still stuck in 4whl. drive. Bad diag. I have also replaced the 4 button selector switch on the dash, with no luck same problem. So yesterday I pulled my batt. and tray out to expose theaccumulator valve, and it is sucked in. I can see a clean spot on the cable were it has moved when I engaged the 4whl. drive last week. Ive checked all the fuses inside the truck and under the hood everything is ok there. Nowtoday I took the vacuum hose off at the firewallfrom the aucuatorvalve that goes to the accumulator valve, the 4whl. drivehigh light is blinking but the truck isback in 2whl. drive. Can anyone help, Thanks.