'00 Won't Shift Into 4-Low

Hello,

Just bought a pristine looking 2000 Chevy Blazer. Looks showroom new.

Aside from a weak lock motor on the driver's door, a power mirror switch that needs replaced, and a CD player that doesn't play CDs, it works very well...

But the 4 Low will not work.

I have 2-hi, 4-hi auto, and 4-hi, but no 4 lo. It tries to shift - there is a definite "thunk" from the transfer case - but the light stays flashing and goes back to whatever mode it was in before. Just a quick shift in and shift out, I guess.

When I shift, I am in neutral and I have tried it with my foot both on and off the brake.

Any help?

Thanks,

Josh <><