1. Identify Potential Problem Areas:
* Cruise control switch stalk: This is a common point of failure, especially with age and moisture intrusion. Look for corrosion on the connector or the switch itself. You might need to remove the steering wheel (carefully!) to access it fully.
* Cruise control module: This is the electronic brain of the system. While less likely to be directly affected by water, a corroded connection to the module is possible. Locate the module (consult a wiring diagram for your specific year and model) and inspect its connectors.
* Vacuum lines: The 1994 Explorer uses a vacuum system for the cruise control. Look for cracks, leaks, or loose connections in the vacuum lines. Moisture can exacerbate existing cracks.
* Speed sensor: The vehicle speed sensor provides speed information to the cruise control. A faulty sensor, or a corroded connector, will prevent the system from functioning correctly. This is often found on the transmission or differential.
* Brake switch: The cruise control should disengage when you press the brake. A faulty brake switch might be causing intermittent problems, especially if water gets into its connector.
* Connectors and wiring: Generally, inspect all connectors related to the cruise control system. Look for corrosion, broken wires, or loose connections. Pay close attention to connectors near the firewall and under the hood where water might accumulate.
2. Troubleshooting Steps:
* Visual Inspection: Start with a thorough visual inspection of all the components listed above. Look for corrosion, loose connections, broken wires, or damaged vacuum lines. Clean any corroded connectors with contact cleaner and a small wire brush.
* Vacuum Line Test: If you suspect vacuum problems, use a vacuum gauge to check for leaks in the lines. Replace any damaged lines.
* Connector Cleaning: Use electrical contact cleaner on all connectors related to the cruise control system. Let them dry completely before reconnecting.
* Test the Cruise Control Switch: If possible, test the switch itself using a multimeter to ensure it's sending the correct signals. This often requires a wiring diagram.
* Check the Brake Switch: Test the brake switch to ensure it's working correctly and not interfering with the cruise control.
3. Repair/Replacement:
* Replace corroded or damaged parts: After your inspection, replace any components found to be damaged, corroded, or malfunctioning. This may include the cruise control switch stalk, vacuum lines, connectors, or the speed sensor.
* Seal connectors: Consider using dielectric grease on connectors after cleaning to prevent future corrosion. This helps repel moisture.
4. Important Considerations:
* Wiring Diagram: Obtain a wiring diagram for your 1994 Ford Explorer XLT. This is crucial for proper testing and repair. You can often find these online through repair manual websites or forums dedicated to Ford Explorers.
* Safety: Disconnect the negative battery terminal before working on any electrical components.
* Professional Help: If you're not comfortable working on your vehicle's electrical system, it's best to take it to a qualified mechanic.
The intermittent nature tied to wet conditions points almost certainly to a connection issue, rather than a component failure *itself*. Focus your efforts on cleaning and inspecting the connectors. If this doesn't solve the problem, then move on to inspecting the other components. Remember to systematically test each element to isolate the fault.
