i have a 2001 blazer LT (don’t know if trim matters but) and the lights on the switch don’t light up, i’ve tried a new switch, has a new actuator, rebuilt tcase but the lights still don’t light up, i know it’s in 2nd so i’m fine for the moment but with the colder season coming on i need to figure out the 4x before snow. i was wondering if anyone has had this issue or knows a solution, it doesn’t have any codes related to the drivetrain system so i’m not sure what could be the issue. i’ve also made sure that all vacuum lines are properly connected and they are.

 

You did not mention checking the transfer case control mode, TCCM. It is located under the passenger side kick-panel.

When these fail, they will start clicking multiple times. This is the relays attempting to set the new setting. Eventually, it will fail completely.

Sometimes the electrical connector becomes corroded too.

 

There is also a fuse for the 4x4 system. If nothing is lighting up, and there's no sounds or anything when you press the selector buttons, then you want to double check that its not a blown or missing fuse. If the fuses are good, and there's no lights or sounds then I agree with Christine that the next place to check is the wires and connections at the TCCM.

Also, does your truck have the 3 button or 4 button selector?

 

Agree on checking the TCCM. On my 2000 ZR2 some of the pins in the connector had rust on them. To clean it up completely I got a cheap terminal removal tool kit on Amazon that had about 40 different pin extractors. Was able to remove each one and sand off the rust. Put a small dab of dielectric grease on them before pushing them back in. The kick panel area seems to hold moisture as rusted pins are pretty common for the Blazers. Also, since you said you just rebuilt the TC might double check encoder motor connection. One last thought, the 1st time I replaced my dash switch it was bad out of the box from China so you never know. Good luck.

 

3-button, or 4-button Auto 4WD? There are very few cheap OBD2 scanners will read TCCM codes (only the 4-button 4WD vehicles have TCCM codes - 3-button TCCM doesn't communicate with the PCM).

To begin, check 20A ATC fuse in underhood fuse panel. After that pull the connectors off the TCCM and check for terminal corrosion on the big red and big black wires.