Here's a general outline. This is not a substitute for a detailed repair manual specific to your 1991 Mercury Sable. Always consult a repair manual for your specific vehicle's year and model for precise instructions, diagrams, and torque specifications. Variations exist even within model years.
1. Preparation:
* Disconnect the negative battery cable. This is paramount for safety.
* Gather your tools: You'll likely need a variety of screwdrivers (Phillips and flathead), possibly sockets and wrenches, and potentially a plastic trim removal tool to avoid scratching the interior. A new ignition switch is also essential, of course. Get the correct one for your vehicle!
2. Accessing the Ignition Switch:
* Steering Column Removal (Partial): This is the most challenging part. You'll likely need to partially disassemble the steering column shroud and lower steering column cover. This involves removing screws and possibly plastic clips. The exact procedure varies depending on the trim level and specific Sable configuration. Your repair manual will be your guide here. Take photos as you go to aid in reassembly.
* Wiring Harness: Once the access panel is removed, you'll see the ignition switch. Before disconnecting anything, carefully study the wiring harness connected to the switch. Take photos or make detailed diagrams showing which wire goes where. This step is absolutely vital for successful reassembly.
* Unlocking the Steering Column: Some models might require some maneuvering to unlock the steering column lock to allow for sufficient movement of the switch.
3. Removing the Ignition Switch:
* Release the Switch: The ignition switch is usually held in place by a retaining clip or screw. Your repair manual will show how to release this. Be gentle to avoid damaging the switch or its housing.
* Disconnect the Wiring Harness: Carefully unplug the wiring harness connector(s) from the back of the ignition switch. Again, refer to your diagrams or photos to ensure correct reconnection later.
4. Installing the New Ignition Switch:
* Install the New Switch: Carefully align and install the new ignition switch, ensuring it's properly seated.
* Reconnect the Wiring Harness: Reconnect the wiring harness connector(s), matching them precisely to the diagrams or photos you made.
* Secure the Switch: Secure the ignition switch using the retaining clip or screw.
5. Reassembly:
* Reassemble the Steering Column: Carefully reassemble the steering column shroud and covers in the reverse order of removal.
* Reconnect the Battery: Reconnect the negative battery cable.
6. Testing:
* Test the Ignition: Turn the key in the ignition to check all positions (accessories, ignition, start). Verify that the ignition operates correctly, and that all accessories function properly.
Important Considerations:
* Repair Manual: A factory service manual or a reputable aftermarket repair manual specific to your 1991 Mercury Sable is indispensable. This guide provides only a general overview.
* Safety: Always disconnect the negative battery cable before working on any electrical components.
* Patience: This job requires patience and attention to detail. Take your time, and don't force anything.
If you're not comfortable performing this repair yourself, take your vehicle to a qualified mechanic. Improperly installing the ignition switch can lead to vehicle malfunctions or even safety hazards.
