Ranger 2WD V6-3.0L VIN V Flex Fuel (2001)
Module Communication Network: Description and Operation
Principles and Operation
The vehicle has two module communication networks: the Standard Corporate Protocol (SCP), which is an unshielded twisted pair cable (data bus plus,
Circuit 914 [TN/OG]) and data bus minus, (Circuit 915 [PK/LB]) and the International Standards Organization (ISO) 9141 communications network,
which is a single wire network (Circuit 70 [LB/WH)). The diagnostic tool can connect to both networks through the Data Link Connector (DLC). This
makes diagnosis and testing of these systems easier by allowing one smart tester to be able to diagnose and control any module on the two networks from
one connector. The DLC can be found under the instrument panel between the steering column and the radio.
The SCP communications network will remain operational even with the severing of one of the bus wires. Communications will also continue if one of
the bus wires is shorted to ground or voltage, or if some but not all termination resistors are lost.
The ISO 9141 communications network does not permit intermodule communication. When the diagnostic tool communicates to modules on the ISO
9141 communication network, the diagnostic tool must ask for all information; the modules cannot initiate communications.
The ISO 9141 communications network will not function if the wire 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 will fail.
The Powertrain Control Module (PCM) is connected to the SCP communication network. The PCM controls the engine performance, electronic
ignition, emission controls and on-board diagnostics. Refer to Symptom Chart in Computers and Control Systems. The Passive Anti-Theft System
(PATS) is integrated into the PCM. The PCM controls the PATS system functions as well as illumination of the anti-theft indicator. The PCM stores the
ignition key codes and controls engine disable. Refer to Antitheft and Alarm Systems.
The Restraints Control Module (RCM) is on the ISO 9141 network. The RCM controls the deployment of the air bags based on sensor input. Refer to
Air Bag Systems.
The Generic Electronic Module (GEM) is on the ISO 9141 network. The GEM is equipped on all vehicles.
The GEM controls additional functions that include:
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speed dependent windshield wipers
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illuminated entry and courtesy lamps
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windshield wipers
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warning chimes battery saver
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accessory delay
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power windows
Refer to Multifunction Electronic Control Module (General Module).
The central security module (if equipped) is on the ISO 9141 communication network. The central security module controls keyless entry and door
lock/unlock functions for the vehicle. Refer to Locks.
The 4-Wheel Drive (4WD) control module (if equipped) is on the ISO 9141 communication network. The 4WD control module controls the four wheel
drive for the vehicle.
The 4-Wheel Anti-lock Brake (4WABS) control module (if equipped) is on the ISO 9141 communication network. The 4WABS control module controls
the brake pressure to the four wheels to keep the vehicle under control while braking.
