2004 Mercury MontereyFACTORY OEM SERVICE PROCEDURE

Principles of Operation: Notes

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The vehicle has 2 module communications network protocols:

  • International Standards Organization (ISO) 9141 communications network
  • controller area network (CAN)

The ISO 9141 communications network is a single wire communications network circuit 70 (LB/WH). The CAN is an unshielded, twisted pair cable communications network, circuit 1827 (WH/LG) and circuit 1828 (PK/LG). Both communications networks are connected to the data link connector (DLC). This makes diagnosis and testing of these systems easier by allowing one diagnostic tool to be able to diagnose and control any module on the communications networks from one connector. The DLC can be found under the instrument panel and the steering column.

The ISO 9141 communications network does not permit intermodule communication. 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 circuit is shorted to ground or battery voltage. Also, if one of the modules on the ISO 9141 communications network loses power or shorts internally, communications to that module fail.

Factory Service Tools

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.