Defective wiring between ECU and vehicle speed sensor

The ECU uses information from the vehicle speed sensor to display the vehicle's speed. If the wirings that connect the ECU and sensor are defective, the electrical current may be hindered or stopped. This will prevent the proper speed from being displayed.

Table of Contents

• 1. Symptoms
  • 1.1 Speedometer Displays the Wrong Speed
  • 1.2 Speedometer Doesn't Move

Symptoms

Speedometer Displays the Wrong Speed

If the speedometer is displaying the wrong speed, the ECU may not be receiving the proper signal. If the speed is too low, the current may be lost, or diminished by faulty wiring. If the speed is too high, the problem may be a defective vehicle speed sensor.

Speedometer Doesn't Move

If the speedometer does not move when the vehicle is moving, faulty wiring may prevent the transfer of electrical current from the sensor to the ECU. The ECU will continue to read the vehicle's speed as 0, since it will not receive any signal.