Hi I have a 99 Blazer with the 4 button NP-8 transfer case and the problem I am having is it will go into 4 wheel drive but when I put it back into 2 wheel drive the transfer case shifts out but the front axle stays engaged the only way to get it disengaged is to pull the vacuum line on the vacuum switch on the firewall. Then it is fine untill I put it back in 4wheel drive.

 

I'm wondering if there isn't a problem with the vacuum solenoid that is causing it to stick open until you jostle it by removing the vacuum line.

 

iam having same problem with my 89 s10 blazer.. goes in fine but when i shift out it stays engaged untill i crawl underneath and pull vac line then it dissengages.???

 

Your '89 has a completely different setup. Your problem is likely the vacuum switch on the transfer case, but any further speculation should be done in a new thread on your problem so as not to take this thread into a different direction.

 

Already replaced the vacuum switch that was not the problem

 

The solenoid is supposed to vent the line to the actuator once it turns off. It is solely responsible for that task.

Have you checked to see if the solenoid is being de-energized properly?

 

Do you know were the solenoid gets its signal form ( tccm ) ?

 

The TCCM grounds the lead for the solenoid to trigger it open when in 4wd. Power to the solenoid is provided through the '4wd' fuse.

You could have a grounded out wire at or near the solenoid that is causing the issue...

 

I have power to the vacuum switch whenever the key is on were is the 4wd fuse under the hood or on the side of the dash

 

You should have power to the solenoid whenever the key is on.

Should be easy for you to locate. I'd have to look it up. If you can't find it, I'll dig through my references when i get a chance if you need me to, but I don't have the time right now.