Charging - Service Information Jeep Grand Cherokee WK2

DESCRIPTION

The charging system consists of

1. Generator
2. Generator decoupler pulley (if equipped)
3. Electronic Voltage Regulator (EVR) circuitry within the Powertrain Control Module (PCM)
4. Ignition switch
5. Battery (refer to «BATTERY SYSTEM - SERVICE INFORMATION»(/jeep/grand-cherokee/wk2-2010-2013/remont/charging-system/#battery-system-service-information) for information)
6. Generator lamp (if equipped)
7. Check gauges lamp (if equipped)
8. Voltmeter (refer to «INSTRUMENT CLUSTER - SERVICE INFORMATION»(/jeep/grand-cherokee/wk2-2010-2013/remont/gauges-instrument-panels/#instrument-cluster-service-information) for information)
9. Wiring harness and connections (refer to Wiring for information)

Scheme 36

On gasoline powered engines, the charging system is turned on and off with the PCM (Powertrain Control Module) and ignition switch with engine running. On diesel powered engines, the charging system is turned on and off with the ECM (Engine Control Module) and ignition switch with engine running. The field circuit will not be energized until engine is running and ignition switch on. This voltage is connected through the PCM and supplied to one of the generator field terminals (Gen. Source B+) at the back of the generator. The generator is internally grounded. The generator regulates the field using pin-1 of the field connector (high side driver).

The generator is driven by the engine through a serpentine belt and pulley, or a decoupler pulley arrangement.

The PCM, or ECM receives a voltage input from the generator (5) and also a battery voltage input (7) from the TIPM (Totally Integrated Power Module), it then compares the voltages to the desired voltage programed in the EVR (Electronic Voltage Regulator) software, and, if there is a difference it sends a signal to the generator EVR circuit to increase or decrease output. It uses a Pulse Width Modulation (PWM) to send signals to the generator circuitry to control the amount of output from the generator. The amount of DC current produced by the generator is controlled by the EVR circuitry contained within the generator.

All vehicles are equipped with On-Board Diagnostics (OBD). All OBD-sensed systems, including EVR circuitry, are monitored by the PCM. Each monitored circuit is assigned a Diagnostic Trouble Code (DTC). The PCM will store a DTC in electronic memory for certain failures it detects.

The Check Gauges Lamp (if equipped) monitors: charging system voltage, engine coolant temperature and engine oil pressure. If an extreme condition is indicated, the lamp will be illuminated. This is done as reminder to check the three gauges. The lamp is located on the instrument panel. For additional information, refer to INDICATORS, INSTRUMENT CLUSTER , DESCRIPTION .

Voltage is monitored at the B+ terminal stud to insure it is connected. If the B+ cable is loose, the PCM will shut down generator field. Because of this new feature, pin-2 of the field connector is internally connected to the B+ terminal.

The generator used with diesel engines is internally regulated. The generator and ECM communicate for diagnostics, etc. If the generator regulator becomes disconnected from the ECM, it will still operate, but in a default mode.

CHARGING SYSTEM

The following procedures may be used to diagnose the charging system if

1. the check gauges lamp (if equipped) is illuminated with the engine running
2. the voltmeter (if equipped) does not register properly
3. an undercharged or overcharged battery condition occurs.

Remember that an undercharged battery is often caused by

1. accessories being left on with the engine not running
2. a faulty or improperly adjusted switch that allows a lamp to stay on. Refer to «IGNITION-OFF DRAW TEST»(/jeep/grand-cherokee/wk2-2010-2013/remont/charging-system/#battery-system-service-information__ignition-off-draw-test) for more information.

INSPECTION

The Powertrain Control Module (PCM) monitors critical input and output circuits of the charging system, making sure they are operational. A Diagnostic Trouble Code (DTC) is assigned to each input and output circuit monitored by the On-Board Diagnostic (OBD) system. Some charging system circuits are checked continuously, and some are checked only under certain conditions.

Refer to appropriate Electrical Diagnostics article for more DTC information. This will include a complete list of DTCs including DTCs for the charging system.

To perform a complete test of the charging system, refer to the appropriate Diagnostic Test Procedures and use a diagnostic scan tool. Perform the following inspections before attaching the scan tool.

1. Inspect the battery condition.
2. Inspect condition of battery cable terminals, battery posts, connections at engine block, starter solenoid and relay. They should be clean and tight. Repair as required.
3. Inspect all fuses in both the fuseblock and Power Distribution Center (PDC) for tightness in receptacles. They should be properly installed and tight. Repair or replace as required.
4. Inspect generator mounting bolts for tightness. Replace or tighten bolts if required.
5. Inspect generator drive belt condition and tension. Tighten or replace belt as required.
6. Inspect automatic belt tensioner (if equipped).
7. Inspect generator electrical connections at generator field, battery output, and ground terminal (if equipped). Also check generator ground wire connection at engine (if equipped). They should all be clean and tight. Repair as required.

GENERATOR RATINGS

TORQUE SPECIFICATIONS

The generator is belt-driven by the engine using a serpentine type drive belt. It is serviced only as a complete assembly. If the generator fails for any reason, the entire assembly must be replaced.

OPERATION

As the energized rotor begins to rotate within the generator, the spinning magnetic field induces a current into the windings of the stator coil. Once the generator begins producing sufficient current, it also provides the current needed to energize the rotor.

The stator winding connections deliver the induced alternating current to 6 positive and 6 negative diodes for rectification. From the diodes, rectified direct current is delivered to the vehicle electrical system through the generator battery terminal.

Noise emitting from the generator may be caused by: worn, loose or defective bearings; a loose or defective drive pulley; incorrect, worn, damaged or misadjusted fan drive belt; loose mounting bolts; a misaligned drive pulley or a defective stator or diode.

Scheme 37

Scheme 38

1. Disconnect the negative battery cable.
2. Remove the coolant recovery bottle. Refer to «BOTTLE, COOLANT RECOVERY , REMOVAL»(/jeep/grand-cherokee/wk2-2010-2013/remont/accessory-drive-belts/#engine-cooling-system) .
3. Remove the cooling fan. Refer to «FAN, COOLING , REMOVAL»(/jeep/grand-cherokee/wk2-2010-2013/remont/accessory-drive-belts/#engine-cooling-system) .
4. Remove the lower radiator hose.
5. Remove the upper radiator at thermostat housing.
6. Remove the serpentine belt. Refer to «BELT, SERPENTINE , REMOVAL»(/jeep/grand-cherokee/wk2-2010-2013/remont/accessory-drive-belts/#engine-cooling-system__removal) .
7. Remove the nut (3) and the ground cable (2) from the generator.
8. Disconnect the field generator connector (4).
9. Remove the protective cover (1) from the B+ cable (6).
10. Remove the B+ nut (5) and cable (6) from the generator.
11. Remove the upper generator bolt (1), nut (2), and stud (3).
12. Remove the two lower bolts (5) and the generator (4).

Scheme 39

Scheme 40

1. Disconnect and isolate the negative battery cable
2. Unplug the field circuit (3) from generator.
3. Remove the B+ terminal nut (1) and wire (2).
4. Remove the serpentine belt. Refer to «BELT, SERPENTINE , REMOVAL»(/jeep/grand-cherokee/wk2-2010-2013/remont/accessory-drive-belts/#engine-cooling-system__removal) .
5. Remove the lower front generator mounting retainer (5).
6. Remove the three mounting retainers.
7. Remove the generator from the vehicle.

Scheme 41

Scheme 42

1. Disconnect and isolate the negative battery cable.
2. Remove the air cleaner body. Refer to «BODY, AIR CLEANER , REMOVAL , 5.7L»(/jeep/grand-cherokee/wk2-2010-2013/remont/mechanical/#57l-engine-service-information) .
3. Remove the serpentine belt. Refer to «BELT, SERPENTINE , REMOVAL»(/jeep/grand-cherokee/wk2-2010-2013/remont/accessory-drive-belts/#engine-cooling-system__removal) .
4. Unsnap the plastic insulator cap from the B+ output terminal.
5. Remove the B+ terminal mounting nut at the rear of the generator. Disconnect the terminal from the generator.
6. Disconnect the field wire connector (3) at the rear of the generator by pushing on the connector tab.
7. Remove two generator mounting bolts (1).
8. Remove the generator (2) from vehicle.

3.0L DIESEL

1. Position the generator (4) to the engine and install the upper generator bolt (1), stud (3) and nut (2). Tighten stud (3) to 12 N.m (106 in. lbs.).
2. Install the lower generator bolts (5) finger tight: Tighten bolts to 28 N.m (21 ft. lbs). Tighten nut to 28 N.m (21 ft. lbs).
3. Install the B+ cable (6) and nut (5) to the generator. Tighten nut (5) to 11 N.m (97 in. lbs.).
4. Install the protective cover (1) from the B+ cable (6).
5. Connect the field generator connector (4).
6. Install the nut (3) and the ground cable (2) from the generator.
7. Install the serpentine belt. Refer to «BELT, SERPENTINE , INSTALLATION»(/jeep/grand-cherokee/wk2-2010-2013/remont/accessory-drive-belts/#engine-cooling-system__installation) .
8. Install the upper radiator at thermostat housing.
9. Install the lower radiator hose.
10. Install the cooling fan. Refer to «FAN, COOLING , INSTALLATION»(/jeep/grand-cherokee/wk2-2010-2013/remont/accessory-drive-belts/#engine-cooling-system) .
11. Install the coolant recovery bottle. Refer to «BOTTLE, COOLANT RECOVERY , INSTALLATION»(/jeep/grand-cherokee/wk2-2010-2013/remont/accessory-drive-belts/#engine-cooling-system) .
12. Connect the negative battery cable.

3.6L

1. Install the generator into the vehicle.
2. Install the three mounting retainers. Tighten to 25 N.m (18 Ft. Lbs.).
3. Install ground wire on mounting stud (4).
4. Install the lower front generator mounting retainer (5). Tighten to 23 N.m (17 Ft. Lbs)
5. Install the serpentine belt. Refer to «BELT, SERPENTINE , INSTALLATION»(/jeep/grand-cherokee/wk2-2010-2013/remont/accessory-drive-belts/#engine-cooling-system__installation) .
6. Install the B+ terminal to the generator stud. Tighten to 11 N.m (97 In. Lbs.).
7. Plug in the field circuit to the generator.
8. Connect the negative battery cable.

5.7L

1. Position the generator (2) to the engine and install the two mounting bolts (1). Torque the bolts to 41 N.m (30 ft. lbs.).
2. Snap the field wire connector (3) into the rear of the generator.
3. Install the B+ terminal eyelet to the generator output stud. Tighten the mounting nut to 12 N.m (108 in. lbs.). CAUTION: Never force a belt over a pulley rim using a screwdriver. The synthetic fiber of the belt can be damaged. CAUTION: When installing a serpentine accessory drive belt, the belt must be routed correctly. The water pump may be rotating in the wrong direction if the belt is installed incorrectly, causing the engine to overheat. Refer to belt routing label in engine compartment, or refer to the «5.7L ENGINE»(/jeep/grand-cherokee/wk2-2010-2013/remont/accessory-drive-belts/#engine-cooling-system__57l-engine) .
4. Install the serpentine belt. Refer to «BELT, SERPENTINE , INSTALLATION»(/jeep/grand-cherokee/wk2-2010-2013/remont/accessory-drive-belts/#engine-cooling-system__installation) .
5. Install the air cleaner body. Refer to «BODY, AIR CLEANER , INSTALLATION , 5.7L»(/jeep/grand-cherokee/wk2-2010-2013/remont/mechanical/#57l-engine-service-information) .
6. Install the negative battery cable.

The Electronic Voltage Regulator (EVR) is not a separate component. It is actually a voltage regulating circuit located within the Powertrain Control Module (PCM). The EVR is not serviced separately. If replacement is necessary, the PCM must be replaced.

The amount of DC current produced by the generator is controlled by EVR circuitry contained within the PCM. This circuitry is connected in series with the generators second rotor field terminal and its ground.

Voltage is regulated by cycling the battery voltage to control the strength of the rotor magnetic field. The EVR circuitry monitors system line voltage (B+) and battery temperature (refer to Battery Temperature Sensor for more information). It then determines a target charging voltage. If sensed battery voltage is 0.5 volts or lower than the target voltage, the PCM energizes the field winding until sensed battery voltage is 0.5 volts above target voltage. A circuit in the PCM cycles the battery side of the generator field up to 100 times per second (100Hz), but has the capability to full field to achieve the target voltage. If the charging rate cannot be monitored (limp-in), a duty cycle of 25% is used by the PCM in order to have some generator output.

See also:
• BATTERY SYSTEM - SERVICE INFORMATION
• INSTRUMENT CLUSTER - SERVICE INFORMATION
• IGNITION-OFF DRAW TEST
• BOTTLE, COOLANT RECOVERY , REMOVAL
• BELT, SERPENTINE , REMOVAL
• BODY, AIR CLEANER , REMOVAL , 5.7L
• BELT, SERPENTINE , INSTALLATION
• 5.7L ENGINE