How do you know if your Transfer Case Control Module is out, or is going out in a 99 Blazer LT with the 4 button 4WD? What are the signs/symptoms? Thanks!!!

None of my 4wd button lights light up (they all flash on real quick when I start the truck), there's no service 4wd light on when the tccm is disconnected but there is one when it is connected, and it wont switch out of 2wd. PLEASE HELP!!!!

 

Does the 4x4 button on the dash click or do anything when you push it? I know those 4x4 dash switches go bad.
On mine it would click and flash but the 4x4 would not engage at the t-case, it would just look like it at the dash. I disconnected the battery and tapped the cables together and it fixed it.
Not sure if that will work for you, if nothing happens at the dash you may need to get a new 4x4 switch, I don't think they are too expensive.

 

What do you mean by click? The buttons feel good when i push them, it's not hard like they're jammed nor are they loose feeling. When it's running there's no lights on on any of the buttons no matter which ones I press. I'll try doin what you suggested.

UPDATE: Tried disconnecting the battery for an hour, and touched the cables together after I disconnected them and before I reconnected them and it's still doing the same thing

 

THIS THREAD has quite a bit of information in it. I would start by verifying that the power is getting to the TCCM and that the switch is working properly (remove it and test resistance values).

 

I had a tech scan the blazer with a tech2 today to try and read the service 4wd code, but it the truck won't allow it to connect to it. It can scan for engine codes and comes back with nothing but when it tries to go into the chassis, it won't allow it to.......

 

If you cannot get the scan tool to communicate with the TCCM and you have gone through all of the fuses to make sure that they all are good, then you may have a bad TCCM. Before condemning the TCCM though, run through all of the electrical connections both at the TCCM itself and on the encoder motor under the truck to make sure that there is no corrosion in the plugs.

 

Fuses were the first things I checked and they were all good. Just checked them again though and they're still good. Connections to the tccm are good as well. I'll put it on a lift tonight and check the connections at the encoder motor.

Does the TCCM control the indicator lights on the 4wd switches? The backlights on them work fine.

 

The back light is controlled off of the interior dimming switch. The rest of the lights in the 4wd switch are controlled by the TCCM.