Code 24, Vehicle Speed Sensor (VSS) Circuit: Notes

ECM provides 5 volts to Vehicle Speed Sensor (VSS). While vehicle is moving, a reed switch inside VSS will open and close, toggling voltage signal high and low. ECM then converts this toggled high/low voltage into vehicle speed that is displayed as MPH/KPH.

Code 24 will set if a constant voltage signal (high or low) is not detected at ECM for at least 4 seconds, with engine running and vehicle moving.

1. Checks if problem is intermittent.
2. If VSS is not receiving 5 volts from ECM, Code 24 will set. Checks for open or short to B+ in Yellow wire, or a faulty ECM.
3. Checks for a poor ground connection, an open in Black/Yellow wire or a faulty VSS.