1. Determine if you have an Automatic or Manual Transfer Case:
* Automatic: These often have a button or rotary dial inside the vehicle, usually near the shifter. The markings might say "4HI" or similar. There might also be a "4LO" option. *These are generally engaged while driving at low speeds.*
* Manual: These require shifting a lever typically located on the floor or near the shifter. This lever will have positions for 2WD, 4HI, and 4LO (low range). *These are generally engaged while stopped.*
2. Engaging 4HI:
* Automatic: Simply press the button or rotate the dial to the 4HI position. You may hear a slight clunk as the system engages. *Make sure you are driving at a low speed or stopped before shifting.*
* Manual: Stop the vehicle completely. Shift the transfer case lever to the 4HI position. You may hear a slight clunk.
3. Disengaging 4HI:
* Automatic: Press the button or rotate the dial back to the 2WD position.
* Manual: Stop the vehicle completely. Shift the transfer case lever back to the 2WD position.
Important Considerations:
* Speed: Generally, engaging 4HI on an automatic system is best done at low speeds, but consult your owner's manual for specific instructions. A manual system should *always* be engaged while stopped.
* Road Conditions: Only use 4HI on slippery surfaces like snow, ice, or mud to improve traction. Avoid using 4HI on dry pavement as it can cause binding and damage to your drivetrain.
* Owner's Manual: The most reliable source of information is your vehicle's owner's manual. It will have specific instructions and warnings for your particular model. It should clearly indicate the type of transfer case you have.
If you're unsure which type of transfer case your 1997 GMC Jimmy has, carefully examine the area around the shifter. Look for a lever (manual) or a button/dial (automatic). Your owner's manual is your best guide.
