ISO 9141 Communications Network
WARNING: This page is about a different car, the 2005 Mercury Mountaineer and 2005 Ford Explorer. However, it is still accessible from the selected car via links, so may be relevant.
The ISO 9141 communications network uses a single wire network circuit 70 (LB/WH). The ISO 9141 communications network does not permit inter-module communications. When the diagnostic tool communicates to modules on the ISO 9141 communications network, the diagnostic tool must ask for all information; the modules cannot initiate communications.
The ISO 9141 communications network does not function if the wire is shorted to ground or voltage. Also, if one of the modules on the ISO 9141 communications network loses voltage or shorts internally, communications to that module fail.