4wd inop
 

I picked up a 2000 blazer about two weeks ago. Initially the four wheel drive seemed to work ok the first couple times I tried it. The other day I noticed all of the selector button yellow lights were on as well as the red neutral light. It is now stuck in 2WD. My vehicle does have the Automatic 4WD. I just installed a new selector panel in the dash, but I've still got the same problem. Any ideas where I go from here? Has anyone seen this before? Any help would be appreciated.

The first step would be to have a check of the OBD codes for the transmission. Are these selector lights still on? Did you notice any recurring clicking sounds from behind the passenger side kick panel? That is where the transfer case control module (TCCM) is located. When they go out the relays start clicking as the system tries to engage. The electrical connector to the TCCM can sometimes become corroded too. Since it is easy to access, it is worth taking a look at the connector.

I do have a check engine light. I'll definitely put the OBD tester on it. Haven't noticed any clicking by the kick panel. I'll take a look at the TCCM. Thanks.

Continuing Issues.
 

So I put the OBD tester on. It's showing O2 sensor code. As for the 4WD. I changed out the TCCM. Went from all 4 yellow lights to just the 2WD light. When I select Auto 4WD or 4WD HI, the yellow lights just blink. 4WD LO the yellow light stays solid and I can hear noises from the transfer case, but it doesn't feel like the front wheels are actually engaging. I'm looking at replacing some of the vacuum lines. Curious if anyone has any other ideas or has seen this before. Thanks in advance.