I have a 2002 Chevy Blazer ZR-2. 4.3L Auto with Auto 4WD, 2HI, 4HI, 4LO. I tried to put it into 4HI and it just blinks, doesnt engage. Same with AUTO 4WD. Then I tried 4LO. It blinked then turned into solid color, indicating that it was engaged. And it was. Then I tried to put it back into 2HI. It took sometime but it finally did. I have never had problems up until now. Any ideas?

 

The difficulty with the Auto4wd transfer case controls is that they are complex and not easily diagnosed. You need a Tech2 (dealer) or equivalent bi-directional scan tool to access the TCCM and run tests.

More often than not, the cause is corrosion on the electrical connections on the TCCM (located behind the passenger side kick panel). Sometimes, the fault is in the encoder motor and replacing it fixes the problem.

 

Where is the encoder motor? Also behind the kick panel?

 

No, the encoder motor is located on the transfer case. It is quite expensive so you will want to make sure that it is the problem.