1. Vehicle Speed Sensor (VSS):
- The VSS is responsible for providing speed signals to the speedometer and cruise control module.
- Check for damage or loose connections to the VSS, which is located near the transmission.
2. Instrument Cluster:
- Issues within the instrument cluster itself can cause the speedometer to stop working.
- Check for loose connections or internal faults in the instrument cluster.
3. Wiring:
- Inspect the wiring between the VSS, instrument cluster, and the cruise control module for any breaks or damage.
- Ensure proper connections at all wiring harness connectors.
4. Faulty Cruise Control Module:
- If the cruise control and speedometer stop working simultaneously, the cruise control module may be faulty.
- Consider testing or replacing the cruise control module.
5. Transmission Output Speed Sensor (TOSS):
- Some 1997 Mustangs have a Transmission Output Speed Sensor (TOSS) that provides speed signals.
- Check the TOSS and its wiring for proper functionality.
6. Powertrain Control Module (PCM):
- The PCM may be experiencing internal issues that affect the speedometer and cruise control.
- Consider having the PCM scanned for trouble codes and consider potential module replacement.
Since you have already checked the fuses, it is recommended to perform the above troubleshooting steps to identify the specific cause of the issue. If the problem persists, it's best to consult with a qualified mechanic or auto electrician who can further diagnose the problem and perform necessary repairs.
