First off, I'd like to say this is my first post and I am new to the board. Secondly, you guys have a wealth of information posted amongst these topics and I've researched the best that I can from within.
So off to my problem...I have a 1999 Chevy Blazer 4dr, 4wd, LT model. I just bought it used and they told me the 4wd wasn't working. Here is what I've done and what I hear.
I turn the ignition key to the on position or start car and a get a series of clicks coming from the passenger side kick panel. These are roughly 6-8 fast clicks (almost like your hazards are on). The blazer starts and initially none of the 4wd lights would come on (Back light or the red lights) Car runs fine and seems to be in 2wd hi.
I check the ATC fuse under hood, swap with a new one same issue.
Checked the 4wd fuse on interior dash/driver's side, swap with new one, same issue.
Note: When I plug the ATC fuse back in, I can hear the clicking inside the blazer again from the area of the passenger kick panel.
I check power to the fuse, leaving the fuse. I pulled the battery, tray, and visibly inspected the actuator under the tray and the hoses back to the actuator solenoid. Disconnected the upper/lower vacuum hoses. I feel vacuum coming from the bottom hose, no vacuum to the top hose. Put the two hose ends together and I hear an audible click by the transfer case and see the actuator pull to the out position. When I remove the hoses from each other, the actuator goes all the way to the in position.
I have swapped out the 4 button 4wd switch in the dash and check connections. So I pull the kick panel off and visually inspect the connections of the TCCM. This is where the clicking is coming from. Soon as I plug in the large 32 pin?? connection it clicks when the key is on, pull connection and the clicking stops.
Initially I thought I might have an issue with the switch itself or the solenoid valve actuator that is near the firewall. Now I am not so sure. None of the red lights would flash quickly when turning the ignition over...that now works but still have the issue with none of the red lights staying on or displaying the mode it's in.
The blazer will not go into 4lo when in neutral, and none of the buttons change modes. I am at a loss and really don't want to drop $2-300 on a TCCM module or the the encoder motor underneath.
Any suggestions, I am banging my head over here....Thank you.
Edit to add: Also note that I had my bro-in-law (gm/ase certified) run diags from the port. No codes, also no trouble codes in the instrument cluster. Only thing that flashes initially is security, when starting car and then everything clears out.
Forgot to tell you that when I had the battery and tray out, if I pushed the actuator valve in by hand I could hear air coming out of the solenoid where the two vacuum hoses connect by the firewall. Is that normal?
Edit to add: I also have the 4 button switch. Auto/wd, 2hi, neutral light, 4hi, 4lo.