Principles of Operation
Note. The information contained in this article is for Escape, Mariner only. For Escape Hybrid information, refer to HIGH VOLTAGE TRACTION BATTERY and HIGH VOLTAGE CONVERTER-INVERTER articles .
The PCM-controlled charging system is unique in that it has 2 unidirectional communication lines between the PCM and the generator/regulator. Both of these communication lines are pulse-width modulated. The GEN COM line communicates the desired setpoint from the PCM to the voltage regulator. The GEN MON line communicates the generator load and error conditions to the PCM. The 3rd pin on the voltage regulator, the A circuit pin, is a dedicated battery voltage sense line.
The PCM uses a calibratable algorithm to estimate battery temperature and to reduce battery damage caused by over and under charging. Using this algorithm, the PCM determines the optimal voltage setpoint for the charging system and communicates this information to the voltage regulator on the GEN COM circuit. While this is occurring, the PCM is also monitoring the GEN MON circuit for charging system information, such as transient electrical loads or errors.
If the PCM senses when the charging system receives a transient electrical load (which may cause poor idle quality as in an idle roll) the PCM can then adjust the injectors opening time to account for the transient electrical load. In this manner, the PCM can maintain a consistent idle speed.
If the PCM detects a charging system error, it broadcasts a CHARGING SYSTEM STATE STATUS message through the CAN communication link, causing the instrument cluster to illuminate the charging system warning indicator. The charging system warning indicator is illuminated if the PCM fails to see a signal on the GEN MON circuit for a time period greater than 500 ms. This telltale is used to indicate over-voltage conditions detected by the PCM.
The PCM also reduces the mechanical load on the starter by initially commanding a low voltage setpoint (using the GEN COM circuit) in order to improve start times and reduce load on the starter and its related system.
Each time the ignition switch is cycled to the ON position, the instrument cluster initiates a bulb check by illuminating the charging system warning indicator. This operation is called prove-out. The PCM then issues a CHARGING SYSTEM STATE STATUS - OK message if the charging system is functioning properly. This message is sent once the engine is running and the charging system is determined to be operating correctly. If the cluster does not receive an OK message, the cluster lights the charging system warning indicator indefinitely. Vehicles equipped with a message center display CHECK CHARGING SYSTEM any time a charging system error is present.
Normal Operation
The generator output is supplied through the battery positive output (B+) circuit 38 (BK/OG) (2.3L), 36 (YE/WH) (3.0L), 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.
With the engine running, the charging system warning indicator is off. The sense A circuit 112 (BK/YE) to the generator field coil is 13-15 volts. The S (stator) circuit (internal to the generator) is used to feed back a voltage signal from the generator to the voltage regulator. This voltage is used by the PCM to turn off the charging system warning indicator. The battery positive output (B+) circuit 38 (BK/OG) (2.3L); circuit 36 (YE/WH) (3.0L) is the generator output supplied to the battery and electrical system.
The generator output is determined by the voltage of the A circuit 112 (BK/YE). The A circuit voltage is compared to a set voltage internal to the regulator and the regulator controls the generator field current to maintain the correct generator output. The set voltage will vary with temperature and is typically higher in cold temperatures and lower in warm temperatures.
With the engine running, the charging system warning indicator is off. The sense A circuit 112 (BK/YE) to the generator field coil is 13-15 volts. The S (stator) circuit (internal to the generator) is used to feed back a voltage signal from the generator to the voltage regulator. This voltage is monitored by the PCM to turn off the charging system warning indicator. The battery positive output (B+) circuit 38 (BK/OG) (2.3L), or circuit 36 (YE/WH) (3.0L), is the generator output supplied to the battery and electrical system.
Under normal operation, the charging system warning indicator is on with the key on and the engine off.
The generator is belt-driven by the engine accessory drive system.
The generator radio suppression equipment reduces interference transmitted through the speakers by the vehicle electrical system.