We have a 2000 Blazer 2dr. Here's what happens: Ignition on, no vacuum to actuator under battery. Press 4hi button, click by transfer case(encoder motor?), lights flash, actuator sucks in, cable pulls from differential to engage but doesn't go to 4wd. 4hi flashes and goes back to 2hi, suction releases from actuator but it stays sucked in instead of letting the cable go. We replaced the solenoid valve on the firewall that has two hoses, one to the actuator under the battery and the other going to the HVAC, manifold, and reservoir side(which we may need to replace). There is suction to the actuator but it won't release it until we pull the hose off of it. There is not a rip or anything on the actuator it seems to be in perfect condition. The cable is kinda in rough shape but we lubed it up and now seems to be ok. Any help would be much appreciated.

 

Since you stated that you have an electronic solenoid, that means you have the 4-button NV236 transfer case. About the only thing you can do yourself to diagnose this issue is check the connections at the encoder motor (on the transfer case) and the TCCM (behind the passenger side kick panel). Aside from that, you would just be guessing as to the cause without getting your TCCM scanned; something that requires a Tech 2 or equivalent full feature scan tool.

With that said, the most common cause of this problem is a faulty encoder on the encoder motor assembly. If this were the cause, you would have to replace the encoder motor to cure the condition.

 

There is a noise down by the encoder motor when the 4hi button is pushed, does that mean the encoder motor is working?

 

It means the motor portion of the encoder motor is working, but the encoder is likely not feeding the position of the transfer case back to the TCCM properly. You really cannot tell without the proper diagnostic tools.

Does it go into 4LO?

 

when the 4lo is pushed(in neutral) a lot of clicking goes on in the tccm then all the lights on the push buttons go out and the service 4wd light comes on.

 

You definitely need to get it diagnosed properly. It could be a problem with the TCCM with things like that happening, but it could also still be an encoder fault. If the service 4wd comes on, the TCCM has stored codes that will point the diagnosis in the right direction.