CTS V6-2.8L (2006)
Speedometer Head: Description and Operation
SPEEDOMETER
The instrument panel cluster (IPC) displays the vehicle speed based on the information from the engine control module (ECM). The ECM sends a 4,000
pulse per mile signal to the cluster discretely. The IPC calculates the vehicle speed using the time difference between consecutive pulses. The
speedometer will default to zero if the time duration since the last speed pulse is greater than or equal to one second.
