2000 Blazer , 4 doors , 4x4 , 4,3l V6, Automatic .

My Blazer is equiped with the 4 buttons 4WD system with RPO NP8 meaning : 2Hi , 4WD auto (Autotrac) , 4Hi , 4Lo .
When in 2Hi, lamp of the button is solid
When pushing 4WD auto button, lamp is flashing continuesly . No small noise of the shaft engagement .
When pushing 4Hi button same thing than for The 4WD auto.
When pushing 4Lo button lamp is flashing and stay flashing even if there is the loud " klang of the 4Lo engaging but I don't have the feeling that I am in 4lo if I take off the car . When pushing back the 2WD button I hear the "Klang of the disengagement of the transfert case.
Concerning the others positions , when I push back the 2Hi button , the 2 Hi lamp flash 1 or 2 times before becoming solid (as usual).

I have checked the vacum lines in the engine compartment and no pipe seems to be leaking .

Before changing any part (transfert case switch, buttons , actuator, vacum electrovalve, transfert case motor, 4wd electronic module ....) I would appreciate your help in the diagnostic and in a check-list indicating me the good schredule for points to investigate .

Thanks in advance .
Serge.

 

No "specialist" with any idea ?

 

Like you said before you start buying parts you will need to take it to someone with a capable scanner to read the 4x4 codes.

The free guys will not do. Well worth the money.

 

I am in France and the only one shop in my area with a capable scanner for GM/USA cars is close for holydays ...... In addition they use the TechII only if you let the car ask for repair , not for a diagnostic before repair ................

 

Check the pins on the TCCM for corrosion.