hello i have a 1997 blazer. itook notice this weekend that i could not get it too go in 4wd lo.2wd and 4wd high the light came on but the 4lo light would not.what do you think the problem would be? thank you for yopur help

 

I am assuming you have the NV233 transfer case (3-button switch on the dash)...

Here is a good thread discussing the troubleshooting and other related information about the NV233:
transfer case / encoder motor switch

And here is the DIY article on how to check the codes stored in the NV233 transfer case control module (TCCM):
OBD2 Non-Automatic Transfer Case Diagnostics