I was checking out the service manual for my 05 Jeep Liberty to figure out how to control my factory Sirius satellite radio without buying the Sir-Alp1. The manual showed something of particular interest. All of the modules in my car communicate via Daimler Chrysler's "PCI" interface which the service manual says is based off of the J1850 VPWM standard (confirmed by the OBD-II (DLC) connector pinout: Pins 2, 4, 5, 16). The service manual also showed the PCI wire connecting to a pin on the ODB-II port which according to Elm's site is the data pin for ODB-II. Could I tap into this PCI bus using the Elm322 RS-232 interpreter and potentially write data to it? The factory radio controls the satellite receiver using this same bus. If I could tap into it I could change the satellite channel from my PC (and maybe even get song information). I was just curious if:
A: The Elm322 supports writing proprietary manufacturer specific codes (such as satellite radio channels)
B: All of these "PCI" buses in the car are connected to each other (all of the components are connected in a daisy chain fashion)
C: I can actually access the main "PCI" bus from the OBD-II "PCI" wire.
Some useful information:
Quote:
The DaimlerChrysler Programmable Communication
Interface (PCI) data bus system is a single wire
multiplex system used for vehicle communications on
many DaimlerChrysler Corporation vehicles. Multiplexing
is a system that enables the transmission of
several messages over a single channel or circuit. All
DaimlerChrysler vehicles use this principle for communication
between various microprocessor-based
electronic control modules. The PCI data bus exceeds
the Society of Automotive Engineers (SAE) J1850
Standard for Class B Multiplexing.
Quote:
The Data Link Connector (DLC) is an industry standard
16-way connector that permits the connection
of a diagnostic scan tool to the Programmable
Communications Interface (PCI) data bus for interfacing
with, configuring, and retrieving Diagnostic
Trouble Code (DTC) data from the electronic modules
that reside on the data bus network within the vehicle.
Sorry for so many questions, but this could be an extremely cool project; almost every function in the car is controlled by messages sent across this bus.