* Wiper Switch: This is the control that tells the motor to operate. A faulty switch can prevent power from reaching the motor, or cause intermittent operation. Replacing it involves accessing the switch (usually under the steering column, but location varies slightly depending on trim level), disconnecting the electrical connectors, and installing the new switch. This often requires some patience and potentially some specialized tools to remove the old switch.
* Wiper Linkage: This is the mechanical system that connects the motor to the wiper arms. It's a series of rods, arms, and pivots. Over time, this linkage can become worn, rusty, broken, or disconnected. A visual inspection is needed to check for cracks, breaks, or loose connections. Repairing the linkage might involve replacing broken parts or lubricating stiff joints. Sometimes, the entire linkage assembly needs replacing.
* Wiper Transmission/Park: Some vehicles have a separate transmission or park mechanism to control wiper arm movement. This can fail and prevent the wipers from moving. This would require detailed inspection of the linkage.
* Fuses and Relays: While less likely if the motor works, a blown fuse or a faulty relay in the wiper circuit could also be the culprit. Check your owner's manual for the fuse box location and the correct fuses for the wipers. Relays are often located near the fuse box or under the hood. Replacing these is generally straightforward.
* Wiring: A break or short in the wiring harness between the switch, relay, motor, and possibly the transmission can interrupt the circuit. This requires a careful visual inspection of the wiring, checking for cuts, frayed wires, or corrosion. Repairing the wiring might involve splicing or replacing sections of the harness – a more involved process that requires some electrical knowledge.
How to Diagnose:
1. Check the fuses and relays: This is the easiest first step.
2. Visually inspect the linkage: Look for any obvious damage, breaks, or corrosion. Try moving the wiper arms manually – if they're stiff or don't move freely, the linkage is likely at fault.
3. Test the switch: This can be tricky without a wiring diagram and multimeter, but if you can safely access the switch wiring and test for power with a multimeter, you can see if the switch is sending power to the motor when activated.
4. Listen for the motor: When you turn the wipers on, can you hear the motor trying to work? If not, you may have an electrical problem upstream. If you hear a click or a whirring sound, the motor is getting power but something else is preventing movement.
Important Notes:
* Safety First: Disconnect the battery negative terminal before working on any electrical components.
* Wiring Diagram: A wiring diagram specific to your 1994 Mercury Sable is helpful for troubleshooting electrical issues. You can often find these online through repair manuals or forums.
* Professional Help: If you're uncomfortable working with car electrical systems or mechanical linkages, it's best to take your Sable to a qualified mechanic.
Start with the simplest checks (fuses and relays) and progress to the more complex ones. A thorough visual inspection is crucial for identifying the source of the problem.
