J1850 Communication Network

J1850 Network Component Location:

The J1850 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.

Three micro-processor based subsystems are included on this network:
- Powertrain control
- Passive anti-theft
- Climate control

The communication bus between these subsystems and the DLC consist of an unshielded twisted pair of wires:
- Circuit 914 (T/O) Bus+
- Circuit 915 (PK/LB) Bus-

Fault Tolerance
The J1850 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 DTC.

Purpose
The information within this section is designed to diagnose J1850 communication network concerns. These concerns may:
- Affect normal functional operations of the vehicle.
- Be directly related to customer concerns.
- Be undetectable except during diagnostics.

Module Identification
Modules included on this J1850 communication network include:

Powertrain Control Module (PCM);
- located in the engine compartment on the RH side of the dash panel.
- a failure of the communication network to the PCM may result in a no start condition.
- if communication to the PCM fails during diagnosis, refer to Communication Systems Diagnostics. Communication System Diagnostics

Passive Anti-Theft System (PATS) Module:
- Located behind the integrated control panel.
- Works in conjunction with powertrain control module to enable or disable engine start function.
- Failure of the passive anti-theft system or communication to the module may result in a no start condition.
- If communication to the passive anti-theft system module fails during diagnostics, refer to Anti-Theft and Alarm Systems for No Communication testing. Passive Anti-Theft Alarm System (Pats)

Remote Climate Control (RCC) Module:
- Located on the A/C evaporator case on the passenger side of the vehicle.
- Loss of communication to PCM may result in degraded automatic temperature control.
- If communication to the RCC module is lost, refer to Electronic Climate Control for No Communication testing.