my name is Bob and I am driving an S10 Blazer in Germany and to be hownest this is a rare vehicle which almost gets no service. Specially on 4wd.

The problem I have is that when I drive in 4WD low or high the system won´t release it back into 2 WD mode. I tested it twice and got lucky the it somehow returned back into 2wd.

My system has a black vacumn tank on the driver side. I assume to have a VCP valve behind the dizzy. Hanve not found yet.
I have the square buttons which allows me to choose the driving mode 2wd 4wd high 4wd low.

If the system won´t allow to disgage then I assume to look on the valve to see it it get a signal for a machanical activity. How would you start simulating this problem in a static condition.

BR
Bob

 

I am guessing that you have a st gen pre 95 and its probobly your front diff actuator. ITs located under your batery tray. They are known to go out.