Module Communications Network Components
- Anti-lock brake system/traction control (ABS/TC) module or stability assist module
- Restraint control module (RCM)
- Vehicle security module
- Powertrain control module (PCM)
- Electronic automatic temperature control (EATC) module
- Driver seat module (DSM)
- Parking aid module
- four-wheel drive (4WD) control module
- Instrument cluster
- Tire pressure monitoring system module
- Power liftgate module
- Air suspension control module
- Climate controlled seat modules (driver and passenger)
- Navigation system module
Refer to SYSTEM WIRING DIAGRAMS (Navigator) or SYSTEM WIRING DIAGRAMS (Expedition) for schematic and connector information.
Scheme 1
Principles of Operation
The vehicle has 3 module communication networks
- The standard corporate protocol (SCP) communications network
- The international standards organization (ISO) 9141 communications network
- The universal asynchronous receiver-transmitter (UART) based protocol (UBP) communications network
The diagnostic tool connects to all 3 networks through the data link connector (DLC). This makes diagnosis and testing of these systems easier by allowing one diagnostic tester to be able to diagnose and control any module on the 3 networks from one connector. The DLC can be found under the instrument panel between the steering column and the radio.
The SCP communications network will remain operational even with the severing of one of the bus wires. Communications will also continue if one of the bus wires is shorted to ground or voltage, or if some but not all termination resistors are lost. The SCP communications network allows inter-module communication.
The ISO 9141 communications network does not permit intermodule communication. When the diagnostic tool communicates to modules on the ISO 9141 communication network, the diagnostic tool must request all information, or initiate module commands.
The ISO 9141 communications network will not function if the wire is shorted to ground or battery voltage. Also, if one of the modules on the ISO 9141 communications network loses power or shorts internally, communications to that module will fail.
The UBP communications network will not function if the wire is shorted to ground or voltage. The UBP is different from the ISO communication network in that it allows intermodule communication.
Anti-Lock Brake System (ABS) Module
The anti-lock brake system (ABS) module or stability assist module is on the SCP communication network. The ABS module or stability assist module controls the brake pressure to the four wheels to keep the vehicle under control while braking. For additional information, refer to ANTI-LOCK CONTROL or ANTI-LOCK CONTROL-TRACTION CONTROL & STABILITY ASSIST .
See also:
• ELECTRONIC ENGINE CONTROLS