Circuit Description
WARNING: This page is about a different car, the 2007 Hummer H2. However, it is still accessible from the selected car via links, so may be relevant.
The powertrain control module (PCM) creates the vehicle speed output signal by pulsing the circuit to ground. The PCM monitors the voltage on the vehicle speed output circuit. If the PCM determines that the voltage is out of the normal operating range, a DTC sets.