1. Check the Speed Sensor: Start by locating the speed sensor. In the 1990 Dodge Dynasty, it's usually situated near the transmission, close to the transaxle. Once found, inspect it for any visible damage, including loose or disconnected wires. If it's faulty or needs cleaning, replace it with a new sensor.
2. Examine the Wiring: Carefully examine the wiring connecting to the speed sensor. Any signs of corrosion or damage to the wires can disrupt its proper functioning. Replace any damaged wires and ensure all connections are secure.
3. Test the Instrument Cluster: Verify if the issue lies in the instrument cluster itself rather than the speed sensor or wiring. This can be done by momentarily grounding the sensor's connector to the vehicle's chassis or grounding stud of the battery. If the speedometer starts working, the problem is most likely in the sensor or its wiring, and not the cluster.
4. Repair or Replace Speedometer Cable (if equipped): Older vehicles such as the 1990 Dodge Dynasty may still use a mechanical speedometer cable. If your car has one, inspect it for any damage or kinks. If found, replace it as necessary.
5. Check Vehicle Grounds: Ensure that all the ground connections in your vehicle are clean, tight, and properly connected. A poor ground connection can affect multiple electrical components, including the speedometer.
6. Scan for Trouble Codes: If your vehicle is equipped with an onboard diagnostic system, use a diagnostic tool or code scanner to check for any stored trouble codes. These codes might provide more information about the underlying problem.
7. Consult a Professional: If none of the steps mentioned above resolve the speedometer issue, consider consulting with a professional mechanic or auto electrician for further diagnostics and repairs.
