|
|
commsystem98.jpg | Hits: 4477 | Posted on: 3/17/05
| View Low-Res
The multiplex communication network provides:
> the ability for module-to-module communication by sharing required inputs and outputs instead of each component having an input or output wired directly to or from each affected module.
> a common link for communication to an off-board tester through the data link connector (DLC) located under the instrument panel to the right of the steering column.
The micro-processor based subsystems included on this network are:
> powertrain control
> climate control
> anti-lock brakes
> anti-theft system
A fifth subsystem, the Natural Gas Vehicle (NGV) Module:
> is used only on Crown Victoria Natural Gas Vehicles (NGV).
> utilizes a stand-alone processor to control the fuel indication system (fuel indication is not supported by the multiplex communication network).
> uses the multiplex communication network to communicate with the powertrain control module (PCM) (12A650)
The multiplex communication bus between these subsystems and the data link connector (DLC) consist of an unshielded twisted pair of wires:
> Circuit 914 (T/O) bus(+).
> Circuit 915 (PK/LB) bus(-).
Fault Tolerance: The multiplex communication network will remain operational in the event:
> one circuit is severed.
> one circuit is shorted to ground.
> one circuit is shorted to battery positive voltage (B+).
> a termination resistor is lost within a module.
> one or more modules fail internally.
Any of these conditions will be detected and reported to the off-board tester during diagnostics in the form of a diagnostic trouble code (DTC).
Purpose: The information within this section is designed to diagnose multiplex communication network concerns. These concerns may:
> affect normal functional operations of the vehicle.
> be directly related to customer concerns.
> be undetectable except during diagnostics.
To properly diagnose a network concern, follow the diagnostic procedure outlined in this section in the order presented.
Module Identification: Modules included on this multiplex communication network include:
Powertrain control module
> located in the engine compartment on the passenger side of the dash panel.
> a failure of the communication network to the powertrain control module may result in a no start condition.
> if communication to the powertrain control module fails during diagnosis, refer to Inspection and Verification.
Electronic Automatic Temperature Control (EATC) Module.
> located in the center of the instrument panel.
> loss of communication to powertrain control module may result in degraded automatic temperature control.
> if communication to the electronic automatic temperature control module is lost, refer to «Section 12-03B» for No Communication Testing.
Natural Gas Vehicle (NGV) Module
> natural gas vehicles only.
> located in front of the A/C condenser core (19712) behind the radiator grille.
> if communication to the Natural Gas Vehicle (NGV) Module fails, refer to «Section 13-01C» for No Communication Testing.
Anti-Lock Brake Control Module
> located in the lower LH side of the engine compartment.
> a failed anti-lock brake module (2C219) may cause a no communication condition on the diagnostic communication network.
> if communication to the anti-lock brake module fails, refer to «Section 06-09» for No Communication testing.
Passive Anti-Theft System Control (PATS) Module
> enables and disables vehicle from starting.
> located under left hand side of instrument cluster.
> if communication to the PATS module is lost, refer to «Section 13-11».
|
