Power to consumers is supplied from the battery (when the engine is not running) and the generator (when the engine is running).
A special feature of the electrical equipment of Ford Mondeo cars is the use of multiplex CAN (Controller Area Network) and LIN (Local Interconnect Network) buses for data transmission.
Due to the increased number of modules and the resulting ever-increasing data flow, three different CAN bus systems are used. The main difference between these buses is their different data transfer rates or areas of application. In order to differentiate between the individual CAN bus systems, the bus systems with a high data transfer rate are referred to as high-speed (HS) CAN buses, and the bus systems with a reduced data transfer rate are referred to as medium-speed (MS) CAN buses or multimedia (MM) CAN buses. These buses operate at a lower speed and are primarily used for communication in the area of convenience electronics or in the multimedia system. To ensure data exchange between the HS-CAN bus, the MS-CAN bus and the MM-CAN bus, two interfaces (gateways) are used. They are used for communication between the three CAN data bus systems and are installed in the multifunction electronic module (GEM) and in the instrument cluster respectively.
The number of modules connected to the three CAN data bus systems depends on the vehicle equipment variant.
Electronic control units (ECU) of the engine, instrument cluster, ABS and automatic transmission, and steering wheel module exchange data via CAN buses. The multiplex CAN bus is a twisted pair of wires.
At the ends of the bus, two parallel resistors with a resistance of 120 Ohm are installed, so the resistance between the wires of the bus should be about 60 Ohm. The system provides a high data transfer rate (500 kbps) and allows to significantly reduce the number of wires in the car.
In addition to CAN buses, the circuit uses LIN buses, through which control and data exchange takes place between the module of the radio equipment remote control system and the tire pressure monitoring system, the block of external lighting switches, the light and rain sensor, headlights, generator, rear door modules, electric window control units and central lock.
The CAN buses are connected to the diagnostic connector located under the instrument panel on the left side (inside the small item box, under the hinged cover).
When a fault occurs in the CAN buses, the ECUs connected to them at that moment record the fault code in the memory.
This code and other fault codes stored in the memory of electronic units can be read by connecting a scanning device to the diagnostic connector.
A number of elements of the electrical circuit of Ford Mondeo cars (interior lighting, door locks, electric windows, windshield and rear window heaters, windshield wipers, etc.) are connected via the electronic control unit for the interior electrical equipment and anti-theft alarm (GEM).
The GEM electronic unit is installed under the instrument panel on the right. This unit allows you to create a delay in turning on and off electrical devices, as well as change the duration of the pause in their operation depending on the selected control algorithm.
In addition, in the event of an unauthorized attempt to enter the vehicle, the GEM unit sounds an alarm using a siren installed under the hood.
The vehicle's electrical equipment diagrams are provided at the end of the book.
WARNING: Carry out any work on the vehicle's electrical equipment only with the battery disconnected.
WARNING: The battery may only be disconnected or connected when the ignition is off.
WARNING: When checking electrical equipment circuits, it is prohibited to short-circuit the wires to ground (check the circuits for a spark), as this may lead to failure of the electrical equipment components.
WARNING: Do not use fuses that are not provided for by the vehicle design or that are rated for a higher current, or use wire instead of fuses.
WARNING: Do not use screwdrivers or metal tools when replacing fuses, as this may cause a short circuit in the electrical circuits.
WARNING: Do not disconnect the battery while the engine is running, as this may damage the voltage regulator and other electronic components of the vehicle.
WARNING: To avoid damage to the generator rectifier block diodes, do not test them with a megohmmeter or test lamp supplied with a voltage greater than 12 V, or test the electrical circuits on the vehicle with these devices without disconnecting the wires from the generator.
WARNING: It is necessary to check the insulation resistance of the generator stator winding with an increased voltage on the generator removed from the vehicle, with the stator winding terminals disconnected from the rectifier unit.
WARNING: When performing electric welding work on a vehicle, it is necessary to disconnect the wires from the battery and generator terminals, as well as the connectors with wires from the electronic engine control unit.
WARNING: Do not touch ignition system components while the engine is running.
WARNING: Regularly clean the battery terminals and cable ends from oxidation and dirt.
WARNING: When charging the battery using a charger, disconnect the battery cables from the battery terminals.
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