Speedometer is not working Inspection

Speedometer is not working Inspection

Common causes

Broken Speed Sensor

This is the most frequent culprit. The sensor (usually located on the transmission) can fail internally or become covered in metal shavings, losing its ability to "read" rotation.

Faulty Fuse or Bad Wiring:

South African roads can be unforgiving. Exposed wires can get wet and short out, or a simple blown fuse can cut power to the entire instrument cluster.

Malfunctioning ECU

If the "brain" of the car has a software glitch or internal hardware failure, it may stop processing the speed signal entirely.

Instrument Cluster Failure

Occasionally, the actual motor or digital display behind the needle fails, even if the sensors are sending the right data.

How it's done

1. Diagnostic Scan: The mechanic connects a scanner to the ECU to look for speed-related fault codes. This tells them if the computer is actually receiving a signal.
2. Visual Sensor Inspection: If a sensor fault is suspected, the mechanic gets under the car to check for physical damage to the sensor or the wiring harness.
3. Circuit Testing: The professional checks the relevant fuses and uses a multimeter to ensure power and ground are reaching the sensor.
4. ECU/Cluster Test: If the sensors and wiring are perfect, the mechanic tests the instrument cluster or the ECU itself.
5. Component Replacement: The old sensor, fuse, or ECU is replaced, and the system is recalibrated.
6. The Test Drive: The mechanic clears the codes and takes the car for a spin to verify the needle moves smoothly and accurately.

What to expect:

• A speedometer diagnostic typically takes 45 to 90 minutes. Because this issue can be as simple as a R50 fuse or as complex as a R10,000 ECU, a professional will work through a process of elimination to save you money. A mobile mechanic can perform this entire check in your driveway, saving you the risk of driving "blind" to a workshop.