1. Check the Vehicle Speed Sensor (VSS):
* Location: The VSS is typically located on the transmission. You'll need to consult a repair manual or online resources (like a forum dedicated to Ford Windstars) to find the precise location for your model year.
* Inspection: Visually inspect the sensor for damage, corrosion, or loose connections. Look for any signs of physical impact or broken wires.
* Testing (Requires a Multimeter): This is the most definitive way to check the VSS. You'll need to disconnect the sensor's electrical connector and use a multimeter to check for continuity and resistance. Again, a repair manual will provide the correct specifications for your VSS. Incorrect readings indicate a faulty sensor.
2. Instrument Cluster Issues:
* Loose Connections: Check all connections at the back of the instrument cluster. A loose or corroded connection can disrupt the signal from the VSS.
* Faulty Instrument Cluster: If the VSS checks out, the problem may lie within the instrument cluster itself. This often requires professional diagnosis and potentially replacement or repair of the cluster. It's a more complex and expensive repair.
* Fuse/Circuit Breaker: Check the fuse box for a blown fuse related to the instrument cluster or speedometer.
3. Wiring Harness:
* Damage/Breaks: Inspect the wiring harness running from the VSS to the instrument cluster for any cuts, chafing, or damage. Rodents can sometimes chew on wiring.
4. PCM (Powertrain Control Module):
* Rare but Possible: A faulty PCM is less likely, but it's possible it's not receiving or processing the signal correctly. This requires professional diagnosis using a scan tool.
Troubleshooting Steps:
1. Start with the easiest checks: Inspect fuses and visually examine the VSS and its connections.
2. Use a multimeter: Testing the VSS with a multimeter is crucial for accurate diagnosis.
3. Consult a Repair Manual: A repair manual specific to your 2000 Ford Windstar is invaluable for pinpointing the VSS location, connector details, and wiring diagrams.
4. Seek Professional Help: If you're uncomfortable working with electrical components or cannot locate the problem, take your Windstar to a qualified mechanic.
Important Note: Driving with a malfunctioning speedometer is unsafe. It's best to address this issue promptly. Also, keep in mind that a faulty VSS might also affect other systems related to the transmission and engine control.
