Ford
Type:
    Powertrain - Vehicle Speed, Idle Control, and Auxiliary Inputs - ISO/SAE Controlled
Description:
    VSS or PSOM (Aerostar/F-Series) Performance Conditions
Cause:
    Engine running, engine speed above the TCC stall speed, then the PCM detected a loss of the VSS signal over a period of time The VSS signal comes from the VSS, TCSS, ABS Module, GEM or CTM (module)

Generic
Type:
    Powertrain - Vehicle Speed, Idle Control, and Auxiliary Inputs - ISO/SAE Controlled
Description:
    Vehicle Speed Sensor "A" Range/Performance

GM
Type:
    Powertrain - Vehicle Speed, Idle Control, and Auxiliary Inputs - ISO/SAE Controlled
Description:
    Vehicle Speed Sensor Circuit Performance Conditions
Cause:
    Engine running, brakes not applied, then the PCM detected the VSS input went from over 18 mph to 0 mph in less than 2 seconds.