2001 chevy blazer

On my ZR2 Blazer I can’t figure out why the transfer case will not shift into 4 wheel drive. It worked a few days ago and now nothing. I no longer hear the transfer case shift all I hear is a little click at the transfer case.

First of all, my deepest sympathy. Don’t worry, once all the moving parts have been replaced a Blazer is pretty dependable. A couple of things I’ve learned from my 2000 Blazer LT 4wd.

  1. A Chevy Tech I know mentioned the Transfer Case Control Module (TCCM) has a tendency to freeze up if 4wd is not used on a regular basis. To reboot the module, disconnect the wiring harness to power it down or disconnect the battery negative terminal for a few minutes. The TCCM is located behind the right kick panel. Check the connection for any corrosion and clean if necessary.

  2. Check the vacuum hoses from the reservoir (located in the left front fender) to the vacuum switch (located on center of firewall for Autotrac, transfer case for Controltrac) and to the front axle vacuum actuator (underneath battery). At this age the vacuum lines start to rot, I’ve had to splice a few on my Blazer.

  3. Last year the vacuum switch failed on the Blazer. The transfer case would switchover to 4wd, but the front axle would not engage. On my Blazer the switch was mounted on the firewall. I disconnected the vacuum hose on the switch and connected them. After this the front axle engaged. The 4wd drive system has been working fine since the switch was replaced.

Here’s a link that can explain things better than I did.

No luck with any of that

When I hit the 4 hi or 4 lo I can hear the tccm click however I will not hear the transfer case shift into 4 wheel drive.