Here's a general outline of the process. Specific steps may vary slightly depending on the exact trim level and any modifications to your vehicle:
1. Safety First:
* Disconnect the battery's negative terminal. This prevents accidental shorts and protects your electrical system.
2. Gather Tools:
* Ignition lock cylinder removal tool: This is a specialized tool and is essential. It's designed to compress the retaining clip that holds the cylinder in place. You won't be able to remove it without this.
* Screwdrivers (Phillips and flathead): May be needed depending on access to screws or trim pieces.
* Pliers: Potentially needed to help with manipulating small parts.
* Penetrating oil (like PB Blaster): To help loosen any stuck components.
* Shop rags or paper towels: To keep the area clean.
3. Accessing the Ignition Cylinder:
* Steering column shrouds: You'll likely need to remove plastic shrouds and trim pieces around the steering column to gain access to the ignition cylinder. These are usually held in place by screws or clips.
4. Removing the Ignition Cylinder:
* Insert the removal tool: Carefully insert the ignition lock cylinder removal tool into the ignition switch. Follow the instructions that come with your specific tool. This tool will usually have a pin or mechanism to compress the retaining clip.
* Turn and pull: Once the retaining clip is compressed, gently turn the ignition key to the "off" position and then pull the cylinder straight out. It may require some firm, but controlled, force.
5. Installation (if replacing):
* Clean the area: Before installing a new cylinder, clean the area around the ignition switch to ensure there's no debris that could interfere.
* Install the new cylinder: Insert the new cylinder into the steering column, ensuring it's properly aligned. Then, release the removal tool (if applicable). This will allow the retaining clip to snap back into place, securing the new cylinder.
* Reconnecting the battery: Connect the negative battery terminal once the new cylinder is securely installed.
Important Considerations:
* Key Code: You'll need the key code for your vehicle to obtain a replacement ignition cylinder. This code is often found on the vehicle's title or registration, or possibly on a sticker within the vehicle (check the glove compartment, owner's manual, etc.). If you do not have the code, you may need to go through a dealership to obtain it. Using the wrong key code will result in a non-functional ignition.
* Damaged Parts: If the ignition lock cylinder is seized or damaged, you might need more specialized tools or expertise to remove it. Forcibly removing a stuck cylinder can easily cause more damage.
* Anti-theft systems: Be mindful of any anti-theft systems (like steering column locks) that might affect your ability to turn the steering wheel or access the ignition cylinder.
This is a simplified overview. A detailed, step-by-step guide specific to your 1989 GMC Sierra would require a repair manual for that model year. Consult a reputable repair manual or YouTube videos for a more comprehensive visual guide before attempting this repair. If you encounter any difficulties, seeking professional help is always recommended.
