Engine Speed (Hardwired and CCD Broadcast)

The TCM uses both direct engine speed input from the Crankshaft Position Sensor or distributor, as well as calculated engine speed input from the PCM over the CCD Bus. The direct input is required to provide immediate information for use by the TCM control logic. The CCD engine speed data is used by the TCM fail-safe logic to confirm that the direct engine speed data is valid.