Scan Tool Testing and Procedures

SPEEDOMETER READING
The Tech 1 scan tool (or equivalent) reading should closely match the speedometer reading with drive wheels turning.

CIRCUIT FAILURE
A failure in the Vehicle Speed Sensor (VSS) circuit should set a Diagnostic Trouble Code:

Code 24 Vehicle Speed Sensor (VSS) Circuit Powertrain Controls - ECM/PCM

OR

Code 72 Vehicle Speed Sensor (VSS) Circuit. Powertrain Controls - ECM/PCM