Charging System - Service Information: Overview Jeep Commander I

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»(ref-288242-S01223403342008062000000) for information)
6. Generator lamp (if equipped)
7. Check gauges lamp (if equipped)
8. Voltmeter (refer to «INSTRUMENT CLUSTER»(ref-288248-S00539521482008062000000) for information)
9. Wiring harness and connections (refer to «SYSTEM WIRING DIAGRAMS»(ref-269567) article for information)

Scheme 23

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. Refer to INSTRUMENT CLUSTER article for additional information.

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.

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»(ref-288242-S22429623802008062000000) in the Battery service information for more information.

DESCRIPTION

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 24

Scheme 25

1. Disconnect negative battery cable at battery.
2. Remove generator drive belt.
3. Unsnap plastic insulator cap (3) from B+ output terminal.
4. Remove B+ terminal mounting nut (2) at rear of generator. Disconnect terminal from generator.
5. Disconnect field wire connector (4) at rear of generator by pushing on connector tab.
6. Remove 1 rear vertical generator mounting bolt (2).
7. Remove 2 front horizontal generator mounting bolts (1).
8. Remove generator from vehicle.

Scheme 26

1. Disconnect negative battery cable at battery.
2. Remove generator drive belt.
3. Unsnap plastic insulator cap from B+ output terminal.
4. Remove B+ terminal mounting nut at rear of generator. Disconnect terminal from generator.
5. Disconnect field wire connector (3) at rear of generator by pushing on connector tab.
6. Remove 2 generator mounting bolts (1).
7. Remove generator (2) from vehicle.

Scheme 27

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Scheme 29

1. Disconnect negative battery cable at battery.
2. Remove plastic dress-up cover at top of engine.
3. Remove coolant reservoir tank mounting bolt and position tank toward rear of engine compartment.
4. Remove air filter cover and air filter element.
5. Remove air filter housing (one bolt).
6. Remove generator drive belt. Refer to «COOLING»(ref-288235) System for procedure.
7. Remove two generator upper mounting bolts (1).
8. Raise vehicle.
9. If equipped, remove skid plate below generator.
10. Disconnect field wire connector (5) at rear of generator (4) by pushing on connector tab.
11. Remove two generator lower mounting bolts (2).
12. Lower vehicle.
13. Remove throttle body-to-cylinder head support bracket (four bolts).
14. Remove throttle body (four bolts). Refer to «THROTTLE BODY»(ref-288225-S37752468022008062000000) Removal in Fuel System.
15. Unsnap plastic insulator cap from B+ output terminal.
16. Remove B+ terminal mounting nut (2) at top/rear of generator and remove cable eye (1) from mounting stud (3).
17. Remove generator from vehicle.