C5 Computer 101
How computers
communicate
between each other and why we
have U Codes.
This
is when a
module is
not responding to the other on the serial data
line. Serial Data line allows sharing a lot of information between the
modules on the same wire. Each system sends to the other a State of
Health (SOH) message. If the system sending the SOH message fails to
receive a SOH message back, then a DTC identifying what system did not
respond will set. This is similar to some computers networks. All the
data line wires joint into two main connectors named the Star
Connector. The Star connectors are located at the left of the BCM.
Here
is the list of the
main C5 computers.
PCM :
Power Train Control
Module
The
PCM is located under
the battery. When the battery leaks acid, it
goes into the PCM and PMC harness. I installed an Optima Red Top
battery. These battery are more resistant to the leaks. I was lucky.
The battery never leak on my PCM. It is located in an area that is
exposed to elements. This is why it is not too clean.
A
view from the
connectors at the bottom of the PCM.
BCM :
Body Control
Module. To see the BCM, the panel at the passenger foot well needs to
be removed.
LDCM
: Left Door Control
Module (located in the doors)
RDCM
: Right Door Control
Module
SCM :
Seat Control Module
(Located under the seats)
DRL :
Daytime Running
Light (Located at the driver pillar)
TAC :
Throttle Actuator
Module (Attached to the PCM)