Grand Caravan FWD V6-229 3.8L VIN L MFI (1997)
Speedometer Head: Description and Operation
CIRCUIT OPERATION
The speedometer receives its information across the CCD Bus from the Body Control Module (BCM). Information on vehicle speed is transmitted
from the Powertrain Control Module (PCM) across the CCD Bus to the BCM.
The PCM receives its information on vehicle speed from the G7 circuit, for vehicles equipped electronic automatic transaxle, from the
Transmission Control Module (TCM).
On vehicles equipped with the automatic transaxle, vehicle speed is sent to the PCM on the G7 circuit from the Vehicle Speed Sensor (VSS),
which is mounted in the transmission.
The BCM calculates the position of the speedometer pointer based on the input from the PCM and adjusts the position of the gauge pointer as
necessary. This signal is sent over the CCD Bus to the instrument cluster.