F 550 4WD Super Duty V10-6.8L VIN S (2000)
Information Bus: Testing and Inspection
Module Communications Network
Principles and Operation
Communications Network - Excursion, Super Duty Series F-250, F-350, F-450, F-550
Principles of Operation
The vehicle has two module communications networks. The Standard Corporate Protocol (SCP) which is an unshielded twisted pair cable (data bus plus,
circuit 914 and data bus minus, circuit 915), and the International Standards Organization (ISO) 9141 network which is a single wire (circuit 70 [/WH]).
The scan 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 ISO 9141 communication network does not permit inter-module communication. When the scan tool communicates to modules on the ISO 9141
communication network, the scan tool must ask for all information; the modules cannot initiate communications.
The SCP communication 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 four wheel and rear wheel Anti-lock Brake Control Module (ABS) is on the ISO 9141 communication network. The module controls brake pressure
to the wheels to keep the vehicle under control while braking. For additional information, refer to Antilock Brake System for rear anti-lock brakes, or
Antilock Brake System for four wheel anti-lock brakes.
The Electronic Crash Sensor Module (ECS) is on the ISO 9141 network. The ECS controls the deployment of the air bags based on sensor input. For
additional information, refer to Air Bag System.
The Overhead Trip Computer (OTC) is connected to the ISO 9141 communication network. The OTC computes and displays in metric or english:
average fuel economy, distance to empty, and compass heading. Refer to Instrument Panel, Gauges and Warning Indicators.
The Generic Electronic Module (GEM) is on the ISO 9141 network. The GEM can control such systems as warning chimes, interior and exterior lamps,
keyless entry, wipers, power windows, and four wheel shift on the fly. For additional information, refer to Multifunction Electronic Control Module.
The Parking Aid Module (PAM) is connected to the ISO 9141 communication module. The module controls sensors in the rear bumper that detect close
objects when the vehicle is in reverse. For additional information, refer to Parking Assist System.
The Powertrain Control Module (PCM) is on the SCP communication network. The PCM controls the engine for better fuel-economy, emissions
control, and failure mode detection and storage. For additional information, refer to Powertrain Management for diagnosis and testing of the PCM.
The Auxiliary Powertrain Control Module (APCM) is connected on the SCP communication network. The APCM provides an operator interface to the
drive-by-wire powertrain control system to effect charge protection, rpm control, and manual throttle control between 1300 and 2500 rpm.
The Passive Anti-theft System (PATS) module is connected on the SCP communication network. The PATS module enables or disables the PCM to
deter drive away theft. For additional information, refer to Antitheft and Alarm Systems.
Inspection and Verification
1. Verify the customer concern.
2. Visually inspect the following for obvious signs of electrical damage:
VISUAL INSPECTION CHART
Electrical
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Central Junction Box (CJB) fuse 3 (20 A)
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Damaged wiring harness
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Loose or corroded connectors
3. If the concern remains after the inspection, connect the scan tool to the Data Link Connector (DLC) located beneath the instrument panel and
select the vehicle to be tested from the scan tool menu. If the scan tool does not communicate with the vehicle:
^
check that the program card is correctly installed.
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check the connect ions to the vehicle.
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check the ignition switch position.
If the scan tool still does not communicate with the vehicle, go to Pinpoint Test K. See: Excursion, Super Duty Series F-250, F-350, F-450,
