Chevy blazer
BF Guru
Joined: Dec 2016
Posts: 5,588
From: Moscow, ID
Welcome to the forum. This is the place to figure out what is going on.
Before members can help, we'll also need to know if you have the 3-button or 4-button type transfer case. The 4-button one also has a "Auto 4wd" button in addition to the 2hi, 4hi, and 4lo buttons.
Common issues with the 4wd system include bad transfer case control modules (TCCM), bad connections to the TCCM, and no vacuum supply to the front axle actuator. There are other other causes, but these are a good start.
We will also need to know any other symptoms, e.g., Do the buttons for the 4wd activation blink when you request a change in the drive setting? Do you hear repeated clicking from under the passenger side kick panel (where the TCCM is located)? Does your HVAC system work correctly to direct air to the desired ducts? The HVAC system also uses engine vacuum so if that system is not working correctly, then it will also affect the front axle engagement.
Before members can help, we'll also need to know if you have the 3-button or 4-button type transfer case. The 4-button one also has a "Auto 4wd" button in addition to the 2hi, 4hi, and 4lo buttons.
Common issues with the 4wd system include bad transfer case control modules (TCCM), bad connections to the TCCM, and no vacuum supply to the front axle actuator. There are other other causes, but these are a good start.
We will also need to know any other symptoms, e.g., Do the buttons for the 4wd activation blink when you request a change in the drive setting? Do you hear repeated clicking from under the passenger side kick panel (where the TCCM is located)? Does your HVAC system work correctly to direct air to the desired ducts? The HVAC system also uses engine vacuum so if that system is not working correctly, then it will also affect the front axle engagement.
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