Charging System - General Information: Overview Ford Fusion I рестайлинг

Principles of Operation

The PCM controlled charging system determines the optimal voltage set point for the charging system and communicates this information to the voltage regulator. This system is unique in that it has 2 unidirectional communication circuits between the PCM and the generator/regulator. Both of these communication circuits are pulse-width modulated (PWM). The generator communication (GENCOM) circuit communicates the desired set point from the PCM to the voltage regulator. The generator monitor (GENMON) circuit communicates the generator load and error conditions to the PCM. The third circuit on the voltage regulator, the A circuit, is a dedicated battery voltage sense circuit.

The charging system voltage is controlled by the PCM. The generator charges the battery, and at the same time supplies voltage for all of the electrical loads that are required. The battery is more effectively charged with a higher voltage when the battery is cold and a lower voltage when the battery is warm. The PCM is able to adjust the charging voltage according to the battery temperature by using a signal from the intake air temperature (IAT) sensor. This means the voltage set point is calculated by the PCM and communicated to the regulator by the GENCOM circuit.

The PCM simultaneously controls and monitors the output of the generator. When the current consumption is high or the battery is discharged (the PCM recognizes this and increases the output of the generator to accommodate), the system is also able to increase the idle speed.

To minimize the engine drag when starting the engine, the PCM does not allow the generator to produce any output until the engine has started. The PCM then progressively increases the output of the generator.

The PCM is responsible for turning the charging system warning indicator off after the engine is started and illuminating it under fault conditions (when the generator is not generating the correct amount of current/voltage with the engine running). The charging system warning indicator is also illuminated by the PCM whenever the key is ON with the engine OFF.

This is a System 4 charging system, which uses the GENMON and GENCOM circuits to control and monitor the charging system through the PCM. System 4 charging systems are virtually identical in design and therefore, share the same diagnostics. The circuit numbers and colors may be different, but the functions are the same. System 4 charging systems may use any type of generator, as the generator type usually depends on the engine packaging and/or output requirements versus cost.

Normal Operation

The generator output voltage is supplied through the positive battery output (B+), circuit SDC14 (RD) terminal on the rear of the generator to the battery and electrical system. During normal operation the charging system warning indicator is off with the key in the ON position and the engine running. The charging system warning indicator is on with the key in the ON position and the engine off.

This pinpoint test is intended to diagnose the following

1. High key-off current drain(s)
2. Engine, generator and battery grounds
3. Positive battery cable
4. Circuit SDC14 (RD) high resistance
5. Battery
6. Generator

Scheme 1

Scheme 2

1. A1 CHECK THE BATTERY CONDITION Carry out the Battery - Condition Test to determine if the battery can hold a charge and is OK for use. Refer to «BATTERY, MOUNTING AND CABLES»(ref-291883) article. Does the battery pass the condition test? YES : Go to A2 . NO : INSTALL a new battery. REFER to «BATTERY, MOUNTING AND CABLES»(ref-291883) article. TEST the system for normal operation.
2. A2 CHECK THE GENERATOR OUTPUT Carry out the Generator On-Vehicle Load Test and No Load Test. Refer to the Component Tests in this article. Does the generator pass the component tests? YES : Go to A3 . NO : REFER to Pinpoint Test B.
3. A3 CHECK FOR CURRENT DRAINS Carry out the Battery - Drain Testing. Refer to the Component Tests in this article. Are any circuits causing excessive current drains? YES : REPAIR as necessary. TEST the system for normal operation. NO : Go to A4 .
4. A4 CHECK THE VEHICLE GROUNDS Key in START position. With the engine running, measure the voltage drop between the generator housing and the negative battery terminal. Is the voltage drop less than 0.1 volt? YES : Go to A5 . NO : CHECK the engine ground, generator ground and the battery ground for corrosion. TEST the system for normal operation.
5. A5 CHECK THE VOLTAGE DROP IN THE B+ CIRCUIT SDC14 (RD) With the engine running, measure the voltage drop between generator B+ C102b, circuit SDC14 (RD) and the positive battery terminal. Is the voltage drop less than 0.5 volt? YES : CHECK if the customer left any electrical system(s) on or if there is an intermittent excessive battery draw. TEST the system for normal operation. NO : CHECK for any corrosion in the B+ SDC14 (RD), positive battery cable and/or connections. REPAIR as necessary. TEST the system for normal operation.

With the engine running, the charging system warning indicator is off. The sense A circuit SBB17 (RD) to the generator field coil is 13-15 volts. This voltage feedback is used by the regulator to maintain the battery voltage at the desired set point. The S (stator) circuit (internal to the generator) is used to monitor generator operation. This circuit and other regulator internal conditions are checked by the regulator to allow the PCM to turn off the charging system warning indicator by sending a message over the controller area network (CAN) bus to the instrument cluster (IC). The positive battery output (B+) circuit SDC14 (RD) is the generator output voltage supplied to the battery and electrical system.

This pinpoint test is intended to diagnose the following

1. Generator
2. PCM

With the engine running, the charging system warning indicator is off. The A circuit SBB17 (RD) from the battery B+ to the generator regulator is 13-15 volts. This voltage feedback is used by the regulator to maintain the battery voltage at the desired set point. The S (stator) circuit (internal to the generator) is used to monitor generator operation. This circuit and other regulator internal conditions are checked by the regulator to allow the PCM to turn off the charging system warning indicator by sending a message over the controller area network (CAN) bus to the instrument cluster (IC). The positive battery output (B+) circuit SDC14 (RD) is the generator output supplied to the battery and electrical system.

This pinpoint test is intended to diagnose the following

1. Generator
2. Circuitry
3. IC
4. PCM

The generator is belt-driven by the engine accessory drive system.

This pinpoint test is intended to diagnose the following

1. Accessory drive belt
2. Loose bolts/brackets
3. Generator/pulley

The generator radio suppression equipment reduces interference transmitted through the speakers by the vehicle electrical system.

This pinpoint test is intended to diagnose the following

1. Generator
2. Circuitry
3. In-vehicle entertainment system

Various control modules within the vehicle operate at a voltage between 10-17 volts. Voltage to these modules is supplied through the vehicle harness to the module(s). Ground for the modules is provided by the modules ground circuit(s). If voltages to these modules rise above 17 volts, DTC B1317 or B1676 may set, or if voltage drops below 10 volts, DTC B1318 or B1676 may set.

This pinpoint test is intended to diagnose the following

1. Battery
2. Charging System
3. Module Voltage Supply
4. Module Ground

Note. DTC B1317 or B1318 can be set if the vehicle has had a discharged battery, has recently been jump-started or has had the vehicle battery charged.