If you have a part-time 4WD system (4x4):
* Shift on the fly: You'll typically have a rotary dial or lever near the gear shift. You must be moving at low speed (under 25 mph ideally, but consult your owner's manual for specifics) to engage 4HI (4-wheel high). To engage, simply rotate/shift to the 4HI position. For 4LO (4-wheel low), you'll need to be stopped, and it's typically a separate position on the dial/lever. Never engage 4HI or 4LO on dry pavement at speed, as it can damage your drivetrain.
If you have a full-time 4WD system (Autotrac):
* Automatic selection: This system automatically engages 4WD when needed. You usually don't have a manual control for switching between 2WD and 4WD. There might be a button or switch for a low range (4LO) that needs to be engaged while stopped. Check your owner's manual to make sure. This system works mainly to provide better traction when driving in snow or slippery conditions.
Regardless of your system:
* Always consult your owner's manual: This is the definitive guide for your specific Trailblazer model. The instructions above are general guidelines, and the exact procedure may vary slightly.
* Engage 4WD only when necessary: Driving in 4WD on dry pavement can cause premature wear and tear on your drivetrain components.
* Be aware of your surroundings: Driving in 4WD requires extra caution and awareness, especially in slippery conditions.
If you're unsure of which system you have, or you're having trouble engaging 4WD, it's best to consult your owner's manual or a qualified mechanic.
