Savana 3/4 Ton Van V6-4.3L VIN X (2003)
Speedometer Head: Description and Operation
SPEEDOMETER
The IPC displays the vehicle speed based on the information from the PCM. The PCM calculates the vehicle speed from the vehicle speed sensor (VSS)
circuit. The IPC receives a class 2 message from the PCM indicating the vehicle speed. The PCM also calculates the vehicle speed based on the wheel
reference vehicle speed class 2 message from the EBCM. The PCM uses the vehicle speed information from the EBCM as a backup. The IPC displays
the vehicle speed information from the EBCM when the PCM detects a malfunction in the vehicle speed sensor circuit.
The speedometer defaults to 0 km/h (0 mph) if the IPC detects a loss of class 2 communications with both the PCM and the EBCM.
