Tools You'll Likely Need:
* Socket Set: Various sizes, including metric.
* Screwdrivers: Phillips and flathead, various sizes.
* Pliers: Needle-nose and regular.
* Wrench: Possibly a small open-end or combination wrench.
* Ignition Switch Removal Tool: This specialized tool helps remove the switch cylinder without damaging it. A well-made pick can sometimes work in a pinch, but the tool is highly recommended.
* Electrical Tape: To secure wiring during reassembly.
* New Ignition Switch: Make sure you get the correct replacement part for your specific vehicle. The part number should be available from your local auto parts store or online.
* Shop Rags: To keep things clean.
Steps (General Outline - Refer to your Repair Manual for Specific Details):
1. Disconnect the Battery: This is crucial to prevent electrical shocks and damage to your vehicle's electrical system. Disconnect the negative (-) terminal first.
2. Steering Column Access: You'll likely need to remove parts of the steering column shroud or trim to gain access to the ignition switch. The specifics depend heavily on your truck's trim level. Your repair manual will be essential here.
3. Release Steering Wheel Lock (If Applicable): If your steering wheel is locked, you'll need to unlock it before you can fully access the ignition switch.
4. Remove the Ignition Cylinder: Using the ignition switch removal tool (or a very carefully used pick), remove the ignition cylinder from the steering column. This is often the trickiest part. Take pictures or notes as you disassemble.
5. Disconnect Wiring Harness: Carefully disconnect the wiring harness from the old ignition switch. Take note of which wire goes where; a diagram or photos are very helpful. Some switches may have connectors that simply unplug, others may require unscrewing terminal screws.
6. Remove the Old Ignition Switch: This may involve removing screws or bolts securing the switch to the steering column.
7. Install the New Ignition Switch: Carefully install the new ignition switch, ensuring that it's properly aligned and seated. Connect the wiring harness, making sure everything matches your previous notes or photos.
8. Install the Ignition Cylinder: Carefully reinsert the ignition cylinder into the new switch.
9. Reassemble: Put everything back together, carefully reinstalling any removed parts. Ensure everything is securely fastened.
10. Reconnect the Battery: Reconnect the battery's positive (+) terminal.
11. Test the Ignition Switch: Test the new ignition switch to ensure it works correctly. Start the vehicle and check all accessories (lights, wipers, etc.) to make sure everything functions as expected.
Important Considerations:
* Safety First: This repair involves working with electrical components and potentially sharp objects. Always prioritize safety.
* Repair Manual: A service manual specific to your 1991 GMC Jimmy is highly recommended. It provides detailed instructions and diagrams that are essential for successful completion.
* Professional Help: If you are uncomfortable performing this repair, it's best to take your vehicle to a qualified mechanic. Incorrect installation could result in electrical damage or safety hazards.
This is a general overview. The specific steps might vary slightly depending on your vehicle's configuration. Again, consult your repair manual for detailed, vehicle-specific instructions before beginning this repair.
