My 2000 blazer goes into 4wd and back to 2wd when sitting still or moving about 10 feet or so. The problem is when I put it into 4wd and drive down the road the "service 4wd" light comes on and when I push the button to go back to 2wd it does not work. Had the switch replaced but still have the problem. Any answers would be helpfull. thanks

 

Answers are all over the forum. You need to get the TCCM scanned by a capable scanner to get the codes that are present. It is trying to tell you what is wrong by turning on the 'service 4wd' light.

 

Thanks I will try That

 

My friend had this problem on his blazer. He got stuck in a bog and decided to put it in 4lo and just whomp on the throttle and got nowhere, so I pulled him out and once he was out he couldn't get it to go back in 2hi and it said service 4x4. He had to drive it 4 miles across town in 4lo, you can imagine how long that took. He finally figured out that one of his vacuum line for the 4x4 was cracked and had to replace it. It has worked fine to this day to my knowledge.