Circuit Description
Modules connected to the class 2 serial data circuit monitor for serial
data communications during normal vehicle operation. Operating information
and commands are exchanged among the modules. When a module receives
a message for a critical operating parameter, the module records the identification
number of the module which sent the message for State of Health monitoring
(Node Alive messages). A critical operating parameter is one which, when
not received, requires that the module use a default value for that parameter.
When a module does not associate an identification number with at least
one critical parameter within about five seconds of beginning serial data
communication, DTC U1000 is set. When more than one critical parameter
does not have an identification number associated with it, the DTC will
only be reported once.
Data Link Connector (DLC)
The DLC is a standardized 16 way connector located below the instrument
panel and close to the steering column. Both the connector design and location
are dictated by industry wide agreements.
All DLCs are required to provide a power supply, hot at all times, to
Pin 16. This circuit is used to power the scan tool. All DLCs supply
a power ground at Pin 4 and a clean signal ground at Pin 5.
The Class 2 serial data circuit is provided at Pin 2
of the DLC.
Class 2 Serial Data Link
The data link is a ring/star configuration with discrete lines entering
and leaving each module. This allows communications to the modules on the
ring if one of the two discrete circuits is open.
A total list of the control modules on the Class 2 Serial Data
Line can include the following:
| • | Cellular Telephone Module |
| • | Dash Integration Module (DIM) |
| • | Driver Door Module (DDM) |
| • | Driver Door Switch Assembly (DDSA) |
| • | Electronic Brake Control Module (EBCM) |
| • | Electronic Suspension Control Module |
| • | Inflatable Restraint Sensing and Diagnostic Module (SDM) |
| • | Instrument Panel Integration Module (IPM) |
| • | LH Middle Door Module (LMDM) |
| • | LH Rear Door Module (RRDM) |
| • | Memory Seat Module (MSM) with A45 |
| • | Navigation Data Entry Processor |
| • | Navigation Data Processor |
| • | Passenger Door Module (PDM) |
| • | Powertrain Control Module (PCM) |
| • | Rear Heater and A/C Control (RCC) |
| • | Rear Integration Module (RIM) |
| • | Remote Function Actuator (RFA) |
| • | RH Front Door Power Window Switch (PDS) (if equipped w/armored
car) |
| • | RH Middle Door Module (RMDM) |
| • | RH Rear Door Module (RRDM) |
| • | Vehicle Interface Unit (VIU) |
The following modules have only one communication line connection to
the Class 2 data circuit:
| • | Cellular Telephone Module |
| • | Driver Door Module (DDM) |
| • | Driver Door Switch Assembly (DDSA) |
| • | Electronic Suspension Control Module |
| • | LH Middle Door Module (LMDM) |
| • | LH Rear Door Module (LRDM) |
| • | Memory Seat Module (MSM) |
| • | Navigation Data Processor |
| • | Passenger Door Module (PDM) |
| • | Rear Heater and A/C Control |
| • | Rear Integration Module (RIM) |
| • | Remote Function Actuator (RFA) |
| • | RH Front Power Window Switch (PDS) (if equipped w/armored car) |
| • | RH Middle Door Module (RMDM) |
| • | RH Rear Door Module (RRDM) |
| • | Vehicle Interface Unit (VIU) |
