ISO 9141 Communication Link

The ISO 9141 communication link:
^ Consists of a single wire, Circuit 70 (LB/W).
^ Provides 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.
^ does not allow module-to-module communications.

The micro-processor based subsystems included on this network are:
^ Anti-lock brakes
^ Supplemental air bag system
^ Keyless entry
^ Power locks and windows
^ Interior lighting control
^ Warning indicator control

Fault Tolerance
The ISO 141 communication link will fail if any of the following occur:
^ Circuit 70 (LB/W) shorted to ground.
^ Circuit 70 (LB/W) shorted to battery positive voltage (B+).
^ The module loses power or ground supply.
^ A module failure shorts the communication network internally.

Purpose
The information within this is designed to diagnose ISO 9141 communication link 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 link concern, follow the diagnostic procedure.

Module Identification
Modules included on this ISO 9141 communication link include:

Air Bag Diagnostic Monitor
^ Located behind the instrument panel to the right of the steering column.
^ A failed air bag diagnostic monitor may cause a no communication condition on the diagnostic communication network.
^ If communication to the air bag diagnostic monitor fails, refer to Air Bags (Supplemental Restraint Systems) for No Communication testing.

Anti-Lock Brake System (ABS) Module
^ Located in the lower LH side of the engine compartment.
^ A failed anti-lock brake module may cause a no communication condition on the diagnostic communication network.
^ If communication to the anti-lock brake module fails, refer to Anti-Lock Brake System for No Communication testing.

Driver Door Module
^ Located behind driver front door trim panel.
^ If communication to the driver door module fails.

Lighting Control Module
^ Located behind the instrument panel to the right of the steering column, refer to Lighting and Horns for No Communication testing.
^ If communication to the lighting control module fails.