wont go into 4wd

i have it in 2wd then i go to put it into 4 either hi or low and it flashes and then the 4wd light will go on but it isnt in 4 it is still in 2wd

i have no idea what the problem is and i really need some advice

i have no idea what the problem is and i really need some advice

Me niether.

What year/model

Check all vacuum lines from TB,to canister,to transfer case.

Check the vac actuator under the battery for tears or holes... Then check the vac line from the vac actuator to the vac switch on the transfer case for dryrot or holes... If that's ok more than likely it's your transfer case motor..

had the same problem on my 2001 Lt but i took it to chevy and they fixed it i forgot what it was.

had the same problem on my 2001 Lt but i took it to chevy and they fixed it i forgot what it was.

:lol: that was useful......

It is one of a few things:

Vacuum lines rotted
Vacuum actuator faulty
Encoder motor faulty

they said it was the idle arm or something

they said it was the idle arm or something

I cannot see how the idler arm would affect it going into 4wd...

I cannot see how the idler arm would affect it going into 4wd...

I concur.