Hybrid Control Module (HCM)
The hybrid control module (HCM) is located on the engine fan shroud near the
powertrain control module (PCM). It acts as a gateway between the high-speed GMLAN
and Class 2 local area networks. If a module in the high-speed system needs
to pass information to the Class II bus, it tags that message and passes it
on to the HCM; the HCM reads the message and passes it along to the appropriate network.
For example, if the starter generator control module (SGCM) needs to display a warning
or alert the driver to a change in operating mode, the HCM would take that message
from the high speed link and pass it to the display controller, which is on the Class II
system. The HCM also:
| • | Controls automatic engine starts and stops |
| • | Controls the energy flowing into/out of the 14-volt and 42-volt batteries |
| • | Enables and disables power for the auxiliary power outlets |
| • | Enables and disables surge smoothing/active damping |
| • | Disables energy generation after airbag deployment |
| • | Controls the auxiliary transmission pump, the power maintenance relay,
and the auxiliary heater pump |
| • | Controls starter generator speed during transmission downshift assists--The
downshift assists support the engine during un-fueled downshifts from 4th to 3rd gear
and 3rd to 2nd gear. The HCM calculates a target engine speed and uses
the starter generator to maintain that target. The starter generator has to control
engine speed, using a torque command, which is within the upper and lower torque limits
specified by the HCM. |
