1. Access the Vehicle Speed Sensor (VSS)
- Find the VSS installed on the transmission near the driver's side of the vehicle towards the front. It will have a single electrical connector attached.
2. Check Wiring
- Inspect the wiring of the VSS for damage or wear, as it can cause speedometer issues. If there is a problem, repair or replace the electrical connector as needed.
3. Test the VSS
- Start the car and let it reach normal operating temperature.
- Use an OBD-II scanner to monitor the speedometer reading and compare it with your car's actual speed, ideally by running the car in safe conditions on the road or using a dyno machine.
- If the readings match, the VSS is working correctly.
4. Replace Speedometer Cable
- If testing with an OBD-II scanner is not feasible and you suspect a faulty speedometer cable, you will need to replace it.
- Disconnect the cable from the VSS and the speedometer (usually behind the dashboard).
- Install the new cable, connecting it securely.
5. Check VSS Gear
- In some vehicles, the VSS utilizes a small plastic gear that can wear out, affecting speedometer accuracy.
- If this applies to your vehicle and the gear is worn, replace it.
6. Test the Speedometer
- Take your car for a test drive and confirm that the speedometer readings are accurate compared to your car's actual speed.
