However, here's a general overview of the process. Remember, this is not a substitute for a proper repair manual and should only be used as a general guideline.
Tools you'll likely need:
* Repair manual: Absolutely crucial for specific instructions and diagrams.
* Screwdrivers: Phillips and flathead, various sizes.
* Sockets and wrenches: Sizes will vary depending on your vehicle.
* Needle-nose pliers: For working in tight spaces.
* Wire strippers/crimpers: If you need to replace any wiring.
* New ignition switch: Make sure you get the correct part for your specific model and year.
* Possibly a steering wheel puller: Depending on how the ignition switch is accessed, you may need to remove the steering wheel. This is a potentially dangerous step, so be extremely careful.
General Steps (May vary significantly based on your specific Jimmy):
1. Disconnect the battery: This is the most important safety step. Disconnect the negative (-) terminal first.
2. Remove the steering wheel (if necessary): Your repair manual will detail this process. It involves removing the horn contact, the retaining nut, and possibly using a steering wheel puller. This is potentially hazardous; improper removal can damage the steering column.
3. Access the ignition switch: This usually involves removing parts of the steering column shroud or other interior panels. Your repair manual will show you exactly what to remove. Be careful not to damage any wiring or trim pieces.
4. Disconnect the wiring harness: Carefully disconnect all wiring connectors from the ignition switch. Take photos or make detailed notes of the wiring connections before disconnecting anything to ensure you reconnect them correctly. You'll likely need to label each wire.
5. Remove the ignition switch: The switch itself is typically held in place by screws or a retaining clip. Your manual will show how to remove it.
6. Install the new ignition switch: Follow the reverse procedure of removal, making sure the new switch is correctly seated.
7. Reconnect the wiring harness: Reconnect all wiring harnesses according to your notes or photos. Double-check everything before proceeding.
8. Reinstall components: Reinstall all the parts removed earlier, including the steering wheel (if removed).
9. Reconnect the battery: Reconnect the positive (+) terminal last.
10. Test the ignition system: Test all ignition functions to ensure everything works correctly (starter, accessories, lights).
Important Considerations:
* Security: The ignition switch often includes the locking mechanism. Ensure you have the correct key for the replacement switch. You might need the VIN number to get a correct key matched to the new switch.
* Wiring: Incorrect wiring can damage the vehicle's electrical system. Take your time and be meticulous.
* Steering Wheel Removal: This is a complex step that could damage the vehicle. Be extremely cautious, or seek professional help.
Again, using a repair manual specific to your 1985 GMC Jimmy is absolutely essential. This is a complex repair, and attempting it without proper guidance can lead to damage or injury. If you are not comfortable with automotive repair, it's best to take your vehicle to a qualified mechanic.
