If you're experiencing speedometer issues, the problem is likely one of the following:
* Faulty Speed Sensor: This is the most common culprit. The sensor itself might be malfunctioning, delivering inaccurate or no data. It needs to be replaced, not reset. It's typically located on the transmission or differential (depending on the specific setup - you'll need to consult a repair manual or online resources specific to your vehicle's year, make, and model to determine the exact location).
* Wiring Problem: A broken, corroded, or loose wire connecting the speed sensor to the PCM (Powertrain Control Module) can also cause speedometer problems. Inspection of the wiring harness is necessary.
* PCM (Powertrain Control Module) Issue: The PCM receives the signal from the speed sensor and processes it. A malfunctioning PCM could be the cause. This requires professional diagnosis and potentially replacement.
* Vehicle Speed Sensor (VSS) Ring (ABS sensor): This is a component on the transmission/differential which the speed sensor reads. Damage to the VSS ring will result in inaccurate speedometer readings.
* Instrument Cluster Problem: In rare cases, the speedometer itself within the instrument cluster could be faulty.
What to do:
1. Diagnose the Problem: Don't start replacing parts randomly. Get a diagnostic code read. An OBD-II scanner (available at auto parts stores) can retrieve diagnostic trouble codes (DTCs) that will pinpoint the likely problem. If it relates to the speed sensor circuit, you'll know where to look.
2. Inspect the Speed Sensor: Once you've located the speed sensor (refer to a repair manual), check its wiring for damage or corrosion. Visually inspect the sensor for any obvious physical damage.
3. Replace the Speed Sensor (if necessary): If the diagnostic points to a faulty sensor or you've found damaged wiring, replace the sensor and/or repair the wiring. This usually requires some mechanical skill. Again, consult a repair manual for specific instructions.
4. Professional Help: If you're uncomfortable working on your vehicle's electrical or mechanical systems, take it to a qualified mechanic. They have the tools and expertise to properly diagnose and repair the problem.
In short: There's no reset. You need to diagnose and fix the underlying issue. A simple OBD-II scan is the first and most important step.
